Using Mulch in my Greenhouses

On Facebook I see a lot of photos of people's greenhouse. Here in Hawaii, they are often actually high tunnels as opposed to the greenhouses one finds on the mainland. But regardless of what you call them, folks here use them to grow food. Sometimes plants are grown right in the ground, but more often than not, they are growing in some sort of raised bed or container because of our lava rock ground. What I've noticed is that no one seems to use mulch in their greenhouses. I'm not sure why.

I mulch the soil in my greenhouses, for the same reason I use mulch in my outdoor gardens. 

... Weed suppression

... Soil moisture retention

... Add to the soil fertility 

Due to the sun and heat, the soil inside the greenhouse dries out quickly. It's common for me to water a greenhouse every other day if it is not mulched. By mulching, I can reduce the need to water to about every 5th day. When it's not windy and sunny, the greenhouse can go a full week between waterings. 

I prefer to use fresh grass clippings for mulch, especially for the greenhouses. It's easy to use and easy to control the thickness of the mulch. 

Mulched basil and young tomato plants in a greenhouse. 

Why Mulch a Temporarily Unused Garden?

"S" emailed me and asked about why I bothered to mulch the soil in the greenhouse that isn't being used at the moment. She didn't see the sense of wasting the mulch or wasting my time. 

Actually "S", that's a great question. And by the way, you'll soon see that it isn't waste at all, at least not from the point of view that I'm coming from. 

Ok. First question to consider......why do I use mulch? 

1- to control weed regrowth

2- to retain soil moisture

3- to protect the soil microbes

4- to provide nutrients to the plants

5- to retain soil so that it doesn't erode or blow away

6- to feed the worms 

If you noticed, I applied water to the greenhouse soil prior to applying mulch. That's should give you a big hint. 

The soil in the greenhouse is fairly young. I'm in the process of building it up. In order to get a good soil ecology going, I've been using generous amounts of fresh compost, supplementing that with livestock manures and urine. To create a preferred environment for soil life, I've been keeping the soil moist and shaded. This has meant watering once or twice a week plus keeping the soil surface covered with mulch. If soil drys out or bakes, I'd be losing much of the soil microbes and other soil life (worms, springtails, etc). The soil life is what decomposes the compost and manure teas, thus eventually providing plant nutrients. It's actually a complex cycle, but basically that's what's going on. 

By covering the soil with mulch, even though I'm not presently growing a crop in the greenhouse, the soil life is preserved and is busily doing its thing. It's in somewhat of a holding pattern since there are no actively growing plant roots. But by being evenly moist and protected from sun, the soil life will do fine until I plant the next crop in the next week or so. The soil life will be able to re-establish their colonies and network, thus recovering from the light tilling by the time the seedlings start to grow. 

So "S", even though I'm not growing an edible crop, I am growing a vast colony of soil life. I utilize this soil life in place of commercial fertilizers. So having a thriving soil life community is extremely important to me. Even with an edible crop, I will tend the greenhouse soil, keeping it moist, shaded, and full of food for the soil life. 

County Mulch

Many people have asked me what I use for mulch. There are many options, and I have my favorites.

#1 ..... Grass clippings. These are readily available as long as I'm willing to put out the effort. I look at  grass mowing as a form of daily exercise. I don't belong to a gym, but I do own a lawnmower. There's lots of walking involved, plus bending, lifting, etc. it's a good work out with the benefit of ending up with several trash cans full of clippings.  

    Grass clippings are easy to apply, I can regulate the depth desired. They breakdown to provide nutrients to the soil and plants. And they stay put even when the tradewibds blow. That can't be said for newspapers and cardboard! 

   The only problem with grass clippings is that I often don't have the time to gather all that I need. 

#2 ..... County mulch. Our county takes green waste and grinds it up, creating a mixed mulch. A good portion of it is coconut tree trimmings. But of course there is just about a little of everything else in there too. It's whatever homeowners bring to the recycle center. 

    When the county grinds up the green waste, it gets piled up in huge windrows. Being fresh, it quickly heats up like a giant compost pile. Anything living, such as coqui frogs or weed seeds, are soon cooked to death. I've been using county mulch now for years and have never had any weeds germinate from it, nor have I seen any form of animal or insect life in the hot mulch. And believe me, it can be really hot, too hot to handle with bare hands when it's first loaded into the pickup truck. 

   I like the county mulch for not only mulching the gardens, but also to help fill the pallet grow boxes. The mulch is coarse but with lots of fines in it. So it's a good mix. Because it is mostly woody, I add manure when filling the boxes, and layer it with green stuff, like weeds or grass clippings....plus a bit of garden soil to add minerals and microbes. 

One pickup truck worth of mulch. It's a nice sized pile. 

Some coarse stuff, lots of medium and fines. 

    

I have only one problem with county mulch -- it's too far away. It's a 3 hour round trip to pick up 2 cubic yards of mulch. That's what fits into the truck if the side panels are on. A pickup typically carries one cubic yard, but with bed sides, I can get 2 in there. 

    I seldom have the opportunity to get the mulch myself. But David often goes to Kona and returns deadhead (nothing in the cargo bed). So once he found out that I desire county mulch, he makes a point of swinging past the mulch yard and getting 2 yards of the stuff for me. It's a win-win situation because I pay him for it, enough to cover his gas and time, basically making his trip to Kona free. 

Late Applied Mulch

"F" commented about my mulching the potatoes. Specifically "F" asked me "Why bother. The plants are almost full grown." 

There's a few reasons why I put the effort into mulching those potatoes. 

...weed control. With all the moisture plus not being able to repeatedly walk through the crop to scuffle hoe, the weeds have been having a party. I see certain weeds returning to the garden beds because of my heavy use of homemade compost and mulch. This is to be expected and normally isn't an issue. But this time around, the weeds haven't been smothered with mulch. Thus the weed seed has been germinating out of control. So what have I done? Did I need to pull or chop weeds prior to applying mulch? No. I simply covered the weeds with the grass clippings. And if Mother Nature allows, I'll apply another layer of mulch in 2 weeks, just about the time some weeds will be poking through this first layer of clippings. So the weeds aren't an issue for me. No need to put the effort into pulling weeds. 

Above, lots of weeds between the potato plant. 

Above, same spot right after the mulch has been applied. 

Above, same rows two days later. Photo taken from the opposite end of the row, so it looks a bit different. The mulch really looks good and does a nice job once it dries out some. 

...prevent greening of the taters. Ever wonder why the garden books recommend hilling your potatoes? Hilling refers to pulling the soil from between the rows and depositing it around the base of the potato plant. No, it doesn't mean making a mound and then planting your seed potato on the top of that mound. Potatoes aren't meant to be planted atop a mound. Hilling accomplishes a few things. It destroys the young weeds in the aisleway, smothers the weeds around the plants, plus builds a barrier against the light for the developing tubers. My mulching does essentially the same. By blocking the light, the tubers won't get green where they are exposed. Green tubers aren't good. 

Under more normal weather patterns, mulching would also help keep the soil moisture fairly constant. That's important for tuber development. Fluctuating soil moisture can result in tuber deformities....splitting, knobbing, hollow hearts. 

Living Mulches

I'm a big believer is using mulch. Mulch helps keep my soil moist, cool, protected from the drying winds, and promotes microbial & worm (plus other beneficial insects) life in the soil. The last item, the microbes and good insects, are ultra important in my soil health and fertilizer program. As I've mentioned many times before, grass clippings are my number one mulching material. I'm forever in need of more. I sometimes get our county mulch (which is mostly coconut tree shreddings mixed with other shredded plants), but it's no longer available locally, thus is costly to bring in. 

There are other mulching techniques besides using grass clippings. Many gardeners on the mainland use wood chips, but they aren't available here too often. Locally I've seen gardeners using cardboard, newspaper, shredded paper, weed cloth, black plastic, and carpeting. But there's one more thing that most people overlook --- living mulch. 

Living mulch is just what it sounds like. It's plants. The idea is to have mulch plants growing as a ground cover. I've heard of some people trying white clover, strawberries, and creeping thyme as a living mulch, but I haven't heard how their results turned out. What I've tried myself is sweet potatoes. 

Sweet potatoes are easy for me. They grow year around. They stay fairly low so that other crops can grow through them. They cost me nothing to propagate. I can pull out the excess and feed them to my livestock. I can harvest greens for our own table, plus harvest a few tubers too. 

I've only just begun to experiment using sweet potatoes as a living mulch. The first crop I matched to them is taro. Taro is a long season crop, taking 9 to 12 months till harvest, and while taro can't compete with grass and most weeds, my taro seems to do fine with sweet potato vines growing among them. The taro towers above the sweet potato vibes, and the vines do fine in their shade. 

My only issue so far is that I'm not brutal enough with the sweet potatoes. I tend to try to avoid stepping on them. But there are times when I need to clean up the taro and remove excess sweet potato greens. I still inwardly cringe when I step on the vines. Eventually I'll get over it, I hope. 

While the sweet potatoes don't keep the soil as moist as the grass clippings, nor do they block out other weeds as well, the vibes seem to do pretty good as a living mulch. They definitely shade the soil and protect it from the sun and wind. They let the rain through. And if the soil is already fairly weed free, few new weeds survive to grow up through it. I don't know yet if the sweet potato vibes help the microbes, soil insects, and worms. 

I'm fairly optimistic so far with this experiment. I think it's worth repeating, expanding, and trying with some other crops, possibly turmeric, sugar cane, pineapples, and bananas to name a few. 

Mulch and New Ground

An experiment............ How much effect would a high nitrogen mulch have on pipinola compared to a low nitrogen mulch? 

Answer .......... A significant difference. 

A few months ago I planted pipinola in an unimproved, shady area that I call "The Valley". It's part of the dry riverbed (once upon a time water flowed here when it rained uphill) that bisects my property. I planted pipinolas fairly evenly spaced over a good section of the area. I guess I put in about three dozen all told. The soil was totally untouched. Rocks were not removed. No soil amendments were applied prior to planting. But the area had been aggressively weedwacked once a month for three months in arow, so most of the weeds were pretty much gone from the real shady areas. 

Over the course of the next few weeks it rained here several times a week, getting the ground fairly moist. It gave the pipinolas a good start with most of them sprouting, though some rotted. I then decided to apply a light mulch, about 1" thick, to help preserve that soil moisture. I would have preferred a 2"-3" thick mulch but I didn't have enough material for that. But I did have some fresh chicken pen litter, so I used it on one section until it ran out. For the rest of the area, I used forest leaf litter. 

Now several months later, I can see a big difference in the pipinola plants. The area that got the chicken pen litter has larger leaves, plenty of vines, and long runners already. The plants have filled out the area, covering the ground. (photo below)

The areas where I used forest leaf litter is quite different. The leaf litter worked to keep the ground moist and the weeds at bay. But the pipinola plants were decidedly not as robust. Yes, they were green and growing. But they had far fewer vines, smaller leaves, and there was lots of ground showing between the vines. (photo below)

Below, you can see that the two areas at side by side. The conditions are almost equal....except for the type of mulch. 

I like the results of this experiment for a few reasons. First, it shows that a good mulch can be quite effective. Not the answer to trump all other answers for starting a garden, but an effective way to start improving soil in a new growing area. 

Second, it shows that fresh chicken manure, used sparingly,  can be successfully used. The emphasis would be on "sparingly". I've always been told that chicken manure had to be composted or aged before using. Mandatory....no discussion allowed. Fresh, it would burn the plants. Ah-ha, that isn't necessarily true. 

Third, it shows that not all soil amendments need to be tilled in to have a beneficial effect. This is important for me, with my rock filled ground. I'm getting more confident that at least some of my starter crops, those where I'm not harvesting roots like with potatoes, can be grown using a high nutrient mulch. I don't know how effective this method would be on other crops, but the pipinolas surely like it. 

As I bring more unused areas into crop growing, I plan to try other high nutrient mulches on various starter crops. What would the results look like using rabbit or horse manure instead of chicken? The chicken litter is based upon grass clippings, so what if I used ground up ferns or leaf litter in place of the grass in the chicken pens? What other starter crops would this method work well with? Sweet potatoes? Taro? Pumpkins? Gourds? Beans? 

Time will tell. Oooooooo lookee, there is plenty of opportunity for more experiments! 

Free Mulch

Today I hit the jackpot. Two big truckloads of tree trimming chippings ------ for FREE dropped off right on the front of the property. Now how great is that! 

When I left to head to town today, I passed the tree trimmers working on my road. With a bit of boldness, I stopped and asked if they needed a place to dump their chippings of the day. "Yes"....what a beautiful sounding answer. So I gave them directions, headed off to town and hoped for the best. 

Didn't get back home until after 5 and I had completely forgotten about the chippings. So it was a pleasant suprise to find two truckloads of ready to use mulch sitting outside the rockwall. Wow, I'm not usually this lucky. In the past everytime I offered a spot for dumping chippings, I was always told that they already had a place lined up. So finally I've won my turn at them. 

Tree trimming chipping make a marvelous mulch. Oh, there's some rather long stuff mixed in, but as a mulch it doesn't matter. I plan to use this on the veggie gardens. I bet I'll use every drop, every chip. 

Improving Soil - My #3 Method

So far I've told you about two ways I start out improving my soil. But I also discovered a third way. Mulch. (Just about everyone has mentioned mulch in response to my first two posts about improving soil. Smart gardeners! Far more observant than I was when I started.) My most commonly used mulch is grass clippings. But all sorts of mulching materials are out there and could be used. Actually my favorite mulching material is the county mulch from the Kona side of the island. It has lots of coconut tree material in it. But it's no longer free for me to get I to my homestead and it's now more difficult to get. 

Compared to the first two methods for improving soil.....compost and planting sweet potatoes......mulching can be a bit trickier. Problems can develop. The top mistakes I've made? (***disclaimer warning! These mistakes apply only to my homestead farm. The effects of mulching can be far different at other locations. Gee, even 5 miles away at my seed farm I see different results to my various experiments.) -------

1- Applying too thick a mulch atop dry soil, thus blocking out the rain. Since most of my rain arrives at under 1 inch at a time, the moisture never got past the mulch. The soil underneath stayed bone dry. 

...remedy: while I could have removed the mulch, I opted to bring in water instead and pump it onto the land. Each day for three days in arow I trucked in 300 gallons of water, thus well watering the area. That solved the moisture issue and things progressed well from there. 

2- Applying a mulch that creates a gley or biofilm layer that prevents wet from reaching the soil below. I once tried spreading a 12" deep layer of fresh grass clippings, then using a sprinkler, watered the area well. (note- I went a tad crazy when I purchased a riding lawnmower and spent a day mowing truckloads of clipping.) Yes, I got the soil beneath the mulch nice a wet. Over the course of the next couple weeks, the grass clippings matted down. Things looked nice. Then we got a heavy rain. When I checked the area the following day, the soil was only damp under the mulch. It looked like no heavy rain had touched it. But the grass clipping mat was soaked, slimy, stinky, and like a felted mat. It had not allowed the rain to penetrate, instead soaking it up and then having the excess find drainage channels. By the way, that grass was slicker than goose shit. One misstep and I'd be at risk of breaking my back in a nasty fall. Super dangerous. 

...remedy: laboriously remove all that slimy, real heavy muck. I used it as part of the fill for some hugelkultur pits. Reapply a reasonable layer of mulch. 

3- Using cardboard for mulching. While I still use cardboard to smother grass, I'm ultra careful around it. Cardboard can get super slippery when it's been wet for awhile, making it ultra dangerous to walk on. It's an accident waiting to happen. I was fooled initially. But after a couple of weeks, the wet cardboard began to get slick between the layers. The more I ayers of cardboard, the worse the problem seems to be. So now when I use cardboard, I never ever walk on it. After it is down for 3-4 months killing the grass, I will pick it up and throw it into a hugel pit or grow box. I don't leave it atop the soil as a mulch where I could walk upon it during a distracted or forgetful moment. 

Above, I used cardboard topped with a bit of grass clippings to smother the grass around young coffee trees. It's time to remove it and replace it with a safer mulch to walk on. 

Above, I've pulled some of the grass clippings aside to show the wet pasty cardboard layer below. Believe me, it's slick! No, I'm not going to film a demonstration video of me walking and slipping on that cardboard. Gee, I already have too many bruises that I'm recovering from due to other farm related knocks and falls. I pass on this one. Just use your imagination. 

4- Using whole eucalyptus leaves for mulching. Like cardboard, these can get real slippery. But it doesn't take so long for it to happen. Once the leaves get wet, it's a case of slip sliding away. If I chop them up with the lawnmower, they don't get nearly as slic, and they decompose faster. So now I just suck them up with the lawnmower along with the grass. It turns out to making a decent mulch. 

5- Applying too thin a mulch. The idea of a mulch is to protect the soil below from the wind and sun. When I spread a thin layer of mulch material, it was just a waste of time. When I went back and checked, the soil beneath it was too dry. I learned that too little mulch was just as much a problem as too much mulch. Nowadays I use 6" of fresh grass clippings, which settles down to 1 1/2" to 2" mulch layer. 

6- Failing to renew the mulch when needed. This is still a failing on my part, basically because I always seem to be in need of more mulch than I have on hand. Over time the mulch settles down and starts to decompose. In most situations I really need to reapply mulch every month. And sometimes even more frequently than that. 

So why does mulch help the soil improve so rapidly? I'm guessing there's a number of factors involved. Mulch helps keep the moist by preventing the sun and wind from drying it out. Moist soil is more hospitable to soil microbes, worms, insects, and other soil denizens. These critters physically move the soil particles about hither and yon. The mulch supplies food to a host of soil life, which in turn leave worm castings, waste, and "dead bodies" in the soil.....which in turn feeds more soil denizens. Ah, the circle of life.  -----  At least, that's the way I figure it. 

Regardless of how things are working, I see that mulch helps poor soil improve fairly rapidly. I've mulched areas where even grasses and weeds were doing poorly, and six months later the soil was ready for a garden. Hard compacted soil back in my rear pasture became for friable under a nice mulch of several months. 

My mulching techniques for new areas.....

...in grassy or heavily weedy area, weedwack everything down (or mow it if that is an option). Then lay down one to four layers of cardboard depending upon how thick and aggressive the grass is. Top it with either a few inches of any kind of mulching material or a light covering of soil, enough to keep the cardboard for blowing away. After 6 months or so, remove the cardboard and start creating a garden. 

...in areas with few weeds or where I have pulled most of the weeds out, skip the cardboard. Water the ground so that they soil will be moist. Top it with 6" of mulch. 3 months later, start creating a garden area. 

One more thing ----  newspaper. I often use newspaper for a mulch the way I use cardboard. Using thick layers blocks the regrowth of grass and weeds, but it tends to get slippery just like the cardboard. But using only 1-2 sheets thick of newspaper with a mulch topping, I don't get that slick problem. But then, only new seedling weeds get smothered out. Some of the established tropical grasses come right through. So I find that using thin layers of newspaper isn't worth the hassle of trying to get it laid down without it blowing away. I get nice tradewinds where I'm located, so finding a windless day in order to use newspaper is difficult. 

What else could I use for mulch? Just about any organic plant material as long as it isn't a plant that will root from the cuttings. Grind it up with a lawnmower or shredder, chop it with a machete or pruners, rake it up if it's already in small pieces like tree leaves. It's all usable. 

Mystery of the Disappearing Mulch

I've  heard plenty of new gardeners complain bitterly that the mulch they use simply disappears. Poof. Most of them believe that it melts or dissolves into the ground, disappearing between the lava rocks. I've heard people say that they put down weed cloth over the lava rock before making their lasagna gardens because they don't want their organic material to wash down between the rocks and disappear. Other gardeners will say that buying or hauling in mulch material isn't worth it because it just disappears. Aaaaahhh, the mystery of the disappearing mulch! Where's Sherlock Holmes when we need him!

Whenever a gardener complains to me about disappearing mulch or compost, apparently hoping for advice or sympathy, I respond , "Of course. I want my mulch to disappear!" 

Mulch and compost seems to disappear because it is decomposing and being consumed by soil life, thus being converted into something that my plants can use as fertilizer. So if it doesn't disappear through the seasons, I'd be worried that my soil was "dead". And if the mulch/compost doesn't degrade, then my plants and garden worms aren't getting fed. So I say, rot baby rot! 

Here in the tropics the mulch and compost seems to decompose fast. Where my homestead is located, the temperature is constantly moderate and we get a decent amount of rain. So conditions are ideal for the soil microbes and the worms. Add to these facts that I don't get cold winters, my organic material gets the opportunity to decompose 12 months a year. The process never stops. When I gardened in NJ, the growing season was much, much shorter. So mulch lasted "the season".....which actually was only 3 months for most crops. That's no different than how long I expect my mulch to last here. It's just that in New Jersey mulch only needed to be applied once, sometimes twice during the year. Here in Hawaii where I can garden year around, it needs to be applied at least four times a year. It just seems to be more than usual, but it's not. 

I rake or till a bit of compost into the soil between each crop. Some of the old mulch also gets worked in. Then I apply fresh mulch. This cycle repeats itself with each crop. Thus each new crop is being fed by the decomposing mulch from crops before them. 

So rather than bemoan disappearing mulch, rejoice that the system is working. I do. I'm glad to see my mulch decomposing. It means that I never need to buy expensive store bought fertilizer. 

More Mulch Discussion

Mike had asked about how I handle mulching. How often do I apply it? How thick? On which crops? Do I plant through it for the next crop or do I remove it before planting? If I remove it, can I reuse it or does it go to a compost pile? All good questions. My answers today are different than what they would have been 12-15 years ago, and may be different if I were answering 10 years in the future. I'm still learning and experimenting with mulches. I am still learning. 

How I use mulch depends upon the crop and situation. For example, I use copious amounts of coarse mulch around the bases of bananas. I just constantly add thin layers of new mulch just about monthly, not for weed suppression but as a slow fertilizer feed as the mulch material decomposes.  Weed control is just a secondary benefit. The banana patches are great locations to dispose of chopped up brush trimmings and weeds. I do the same thing around taro with success, though with taro I also add some manures in with the layers. Taro responds very well to a nitrogen boost about halfway through its growth cycle. 

At the seed farm I'm in the process of creating a soil base. Unlike the homestead which is moist and coolish, it is windy, hot, and dry there. And basically no soil. So mulches are heavily used there to build soil and improve soil structure. I've been using the lasagna method, layering cardboard & newspaper along with coarse material, grass clippings, pulled weeds, waste fruits, manures, soil, cinder, and sand. Where I've been doing this for a couple of years I'm actually making garden spots where taro, sweet potatoes, and beans are successfully growing. This aggressive layering method is a failure at the homestead farm. I think that's because it's too wet there. Lasagna mulching, done to the degree I'm doing at the seed farm, just results in a soggy, anaerobic mat that is slimy and smells on the homestead. Only five miles distance in difference, but this method works at one location but not the other. 

So I'm going to talk primarily about mulch at the homestead farm. At the seed farm, mulch use there is a simple matter of bringing a weekly truckload of cardboard and organic debris, then piling it atop what is already there. Add water. Bingo....done. Since I can't cover the whole acre with one truckload, mulch is applied one small location at a time. Thus crops get planted into the older spots and get more mulch as it becomes available. 

On the homestead farm, I'm working there 7 days a week. So I have the time to apply mulch frequently and fine tune the process. Mulching is primarily done in my food growing areas. My goals are moisture retention, weed suppression, nutrients, and overall soil improvement. My primary mulches for this are grass clippings and brush/tree chippings. I have far more grass clippings than chipped up brush. 

I apply mulch by hand, one wheelbarrow or trashcanful at a time. Labor intensive, but a great workout. No need to buy a gym membership here! Applying by hand allows me to adjust the thickness of the mulch layer. Around young seedlings, maybe just an inch. Around established crops, perhaps 3-4 inches. But I have to be cautious with thick layers since grass clippings can heat up at that thickness, thus damaging the plants. I find its better to apply a couple inches, wait a week, then apply another couple inches if I'm using clippings. Coarser chips can be applied a bit thicker without the heat problem, but it depends upon the weather. If it is dry I can get away with a thicker layer than if I'm getting light rains. Since I garden year around, mulch gets applied year around, usually weekly as I mow grass. 

Most of my vegetable crops get mulched. But some don't depending upon the plants and how they are being grown. Closely seeded peas in a solidly sown bed just get a very light covering of grass clippings at the time of sowing. The peas come up quite thickly, shading the soil themselves. Thickly planted leaf lettuce and radishes get none. But most crops get planted with space between the plants, giving ample opportunity for mulch. The idea is to cover the soil so that the sun cannot reach it. 

When I harvest a crop here is usually some mulch still present that hasn't yet decomposed. If it's only a thin layer, then I just turn it back into the soil as I prepare the bed for the next crop. (I lightly rototill or else hand dig the bed in order to incorporate various soil amendments between crops.) If it happens to be thick, as is the case with potatoes, then I'll scoop it up and put it on an adjacent bed that is still growing. Moving it to a compost pile is simply an inefficient use of my time and effort. Old mulch very well could be added to compost, but adding it to the bed in the next row works just fine too. 

I've been fiddling around with using mulch in the garden aisles. I'm not completely happy with what I've tried so far. Cardboard and newspapers tend to get slippery, posing a falling danger. Same with clippings and brush chips. Wood chops resulted in aisles that were chronically soggy, almost boggy in nature. Coarse mulch was difficult to walk on and had the danger of causing tripping. I like using cracked macnut shells the best so far, but I don't have enough of them. So I'm still working in a solution. Since the aisleways are permanent, I have been thinking of using cinders. 

Pros & Cons of Mulch

Mike asked via email why I use mulch. What are the benefits and the drawbacks? Mike felt that if mulch was so great, then everybody would be using it, right? But he noticed that farms never seem to use mulch and most magazine garden photos don't show mulch being used either.  Good observations! 

There are small farmers using mulch, but mostly on perennial crops. Annual crops are planted with farm equipment in mind, so mulch doesn't fit well into that picture. The exception is the use of plastic mulch....huge sheets of plastic laid down in rows through which a crop is planted. I have seen this technique used for corn, tomatoes, peppers, squash, and melons in certain situations. And a variation of this is the use of red colored mulch to enhance a tomato crop and reflective plastic (white or silver) to repel insects. Big farms can't use organic mulch simply because farming techniques can't accommodate it. Applying vast amounts of mulch would be difficult for most crops. Current systems of weed control, row cultivation, pest control, harvesting all prevent the use of mulch. Except for dust mulching. Depending upon soil type and weather, there are situations where a farmer will use shovel hoes or cultivators to produce a fine surface dust which acts as a moisture retaining mulch to some degree. In orchards, the use of mulch is more common than with annual crops. Here in Hawaii there are macnut farmers who return the harvest debris to the orchard in the form of mulch for under their trees. Others will maintain a layer of volcanic cinder under the trees as a mulch. I saw an orchard in NJ that was trying a fine pebble mulch under the trees. And another using coarse sand. But I can't say how effective those were. Since I saw zero weeds I have to assume that those farmers were also using a herbicide. 

So how about the pros and cons of mulch on my own homestead? Remember that I'm in Hawaii, so I don't need to be concerned with frozen or cold soil in the spring. Mulch in cold zones can keep cold soil from warming up in the spring. 

Pro--- when applied before weeds germinate (or while they are quite tiny), mulch effectively keeps weeds from taking over the garden.

Pro--- soil under a mulch retains moisture far, far better than that exposed to the sun and wind.

Pro--- soil temperature is cooler under a mulch. Most crops prefer cooler-than-air soil for their root zone. 

Pro--- soil micro-organisms thrive under a mulch. They are protected from the sun and wind, plus are exposed to less temperature and moisture fluctuations. 

Pro--- as the mulch decomposes, it supplies nutrients to soil microbes and worms. 

Pro--- worms thrive better under mulch

Pro--- soil structure is better under a mulch. Less apt to have drainage and compaction problems. Less apt to show hydrophobic characteristics. 

Pro-- good utilization of onsite organic material. 

Con--- creates a hiding place for pests. It's easier to miss noticing and finding destructive insects. Slugs like mulch. And so do mice. 

Con--- it is difficult to use on certain crops, especially those that are close to the ground, like radishes, leaf lettuce beds, micro greens, etc. 

Con--- if applied too thickly it can prevent rain from reaching the soil. Also along this same line, too thick mulch can cause the soil to stay too wet under certain circumstances. 

Con--- depending upon the material being used for the mulch, as the mulch decomposes it can rob the soil and crop of nitrogen. 

Con--- applied too thickly, certain materials can generate heat, thus killing or damaging the crop. 

Con--- certain mulch materials will significantly impact soil properties, thus affect not only nitrogen levels but also P, K, and pH. 

Con--- over proliferation of undesirable fungus and molds. Especially a concern when the mulch is matted and wet. It becomes slimy, slippery, and stinky. 

Con--- may contain weed seeds. Especially a problem when using old hay and straw. 

Con--- flammable (sand, cinder, etc not included.) Not a concern on my homestead, but it could be a real serious issue elsewhere. 

Con--- material brought in from other areas could bring pests and disease, plus could contain noxious chemicals. 

What do I use for mulch? Organic material. While cinder may look pretty around my fruit trees, I would have to use a herbicide like round-up for weed control.....or an awful lot of hoeing. No thank you to either.

1- Grass clippings are my number one mulching material. Easy for me to apply. I've learned how to effectively use them while avoiding problems. And I have year around access to them. 

2- Right there along side grass clippings is brush chippings. Chipped up brush and small tree branches make good mulch. 

3- Third is chopped up brush. This makes a coarse mulch. 

4- In the past I've used newspaper and cardboard with varying results. I now only use them in certain situations and seldom ever on my homestead farm. They are better reserved for the seed farm where it is drier and hotter. 

5- macnut harvest debris (husks and shells) make a good mulch for me, but alas they are costly. So I don't use it much. 

6- shredded green waste from the county. I'd use truckloads of this stuff if I had easy, cheap access to it. At one time I did. But not anymore, sigh. 

Mike had two more questions..... How often do I need to reapply mulch? What do I do with the surface mulch when I need to dig or till the soil? Um. How about if I answer those on another post. Otherwise I'd be writing a book here.    :)

Taro & Standing Mulch Update

Each week day I work on a number of different projects rather than just focusing one one until the job is done. I know that most people don't work this way, but sticking with one project till the end seems too much like a job to me. I left those boring drudge jobs behind several years ago. This system that seems hodgepodge to some people works just fine for me. It keeps me interested and enthused with my homesteading efforts. 

Thus this post......this is an update on my new taro patch and standing-mulch project. I started several weeks ago clearing out a brushy area, using the cut up brush as a coarse mulch for the baby taro plants. I cut stuff as I needed it, leaving the rest for the future when I needed more. As I cleared the brush I planted taro. So this is what it looks like today......

The taro in the foreground has produced large leaves because that was the first patch I planted. The further you look back, the younger the plants are. The babies that I planted today you can't even see. 

Back where the younger plants are is the area that was covered in brush several weeks ago. All that brush has been snipped up and used as mulch on the taro. The process took several weeks, adding light layers of mulch repeatedly over time. The coarse mulch layer is about 10 inches thick in the foreground. The neat thing about this type mulch is that it won't form a water impervious mat. Instead, it allows rain through, keeps the soil moist, and blocks weeds. Pretty neat. One of the reasons it doesn't mat is that the brush stems are cut up too and incorporated in the mulch. Yes, very stemmy. It keeps the mulch springy. Those stems will gradually degrade. When this taro is harvested in a year, all the mulch gets dug into the soil, including any stems that haven't rotted. It greatly improves my otherwise pathetic tropical soil. 

In the far back of the picture the ground shows greenery. That's where I harvested standing mulch but am allowing it to regrow. I did not remove the roots. As I expand the taro patch, I will totally remove the brush and roots in order to plant taro. In the meantime, the brush will regrow greenery that I can use as more mulch material later on. One other point about not removing all the brush prior to actually using the space. The greenery will shade the soil surface, keeping the sun from killing the soil microbes. Since I use organic material as my fertilizer, healthy soil microbes are important. 

Standing Mulch

One of my friends is fond of describing my grass and weeds as being "standing mulch". Once mowed, it's mulch, but while it is still growing and green, it's standing mulch. I take advantage of standing mulch whenever I can. Other people seem to be quick to chop things down and haul the debris off to the dump. I'm more apt to utilize that debris. Let me show you an example. 

A couple of weeks ago I harvested a patch of taro that was ready. This gave me a number of "starts" for replanting. Since I had quite a few starts, I decided to create another bed. So I planted these taro starts and lightly mulched them with forest litter, then watered them well.  After 2-3 weeks the plants were growing new leaves and looking pretty good. Time for more mulching. 

Some small weeds were popping up, so first I removed them, adding then to the mulch layer. Now I needed mulch material. I could have created grass clippings, or I could have raked up some forest debris. But growing right next to this taro patch was some weedy brush that I wanted to get out of there so that I could expand this taro bed. 

So the simplest thing to do was chop that greenery up and use it as the mulching material. Those bushes and weeds are standing mulch for this taro bed. 

Using a handheld pruning shears, I grabbed handfuls of greenery and cut it. I could have used a machete but I don't trust myself with one anywhere near a tree. Wild women with a big knife! Eek!  I  just laid the chopped greenery around the bases of the taro plants. I'll let it dry out over the next 3 days then do another layer. Then next week, another light layer. Quick and simple. As the taro needs more mulch, I'll just hack more of the brush down. This creates easily accessible mulch plus removes brush so that I can make a larger garden. Super! 

Grass Clipping Mulch

I'm a big user of mulch, number one for weed control. During drought years, mulch is a major water conservation method. And another major use for mulch is to provide a good environment for the various soil micro organisms, which are what decompose the organic matter thus creating fertilizer for the plants. Lastly, mulch helps maintain an active worm population. 

My most often used mulch is grass clippings. Why? It's what I have the most of. I'd really prefer using our county mulch, but it's no longer available to me in vast quantities at an affordable cost. The county mulch is composed of mostly coconut tree trimmings and made an excellent soil amendment. But it is no longer being delivered to Ka'u. So I've had to resort to my number two favorite....clippings. 

Since I'm a big user of mulch, I finally upgraded from a hand push style mower to a riding tractor. I don't regret the upgrade at all. 

With all the abundant recent rain combined with the time of year, summer, the grass has been growing by leaps and bounds. So I've had no shortage of grass to harvest. The main problem is finding days when the grass is dry enough for mowing. 

I can harvest quite a bit of clippings in just two hours. 

The easiest way I've found so far for transporting the clippings is by loading them into trashcans. 

It might seem to be faster to simply fork them into the back of the pickup truck then unload from there, but that proved not to be the case. I find the trashcan method to be easier on me and take less time. 

When I apply this mulch, I don't pile it too thick. About a 4 inch fluffy layer is enough. That will compress down to around 1 to 1 inch in a week. Just about right. Thick enough to smother germinating weed seeds. Thin enough to allow most rains to reach the soil. If applied too thickly, then the clippings have a tendency to get gloppy and slippery, a sign of anaerobic decomposition. Since I want oxygen to be able to reach the soil, anaerobic decomposition is not good. Another problem of the mulch being too thick is that I get mice living in it. Mice will eat my vegetables. Not good either. 

Do I see slugs? You bet! But then, I see slugs even without mulch. The mulch offers me plenty of benefits, so I'll just deal with the slugs. 

Did you notice something.......red tractor, red truck, red trashcans? Actually yellow and green are my favorite colors, but I'm definitely attracted to red. 

Living Mulch

I've read many accounts on the Internet about living mulches. I admit I have been skeptical. I wonder how many of those accounts were based upon practical experience. Too many suggestions that I've taken from the Internet didn't pan out. (I plan to list them in a separate blog entry for you.)

One idea that I tested was the living mulch. The idea is that you would grow an understory plant that would keep weeds out but let water in. And supposedly be ok with the veggies that you're trying to grow. I've seen all sorts of ideas that other gardeners are supposedly successfully using claiming that veggie plants thrived, but I have to say that I have my doubts. 

I've read claims of growing veggies amid a short growing grasses. Some claim miracle results using clover. Yet others claim the direct planting right into their lawns works great. Yet other gardeners claim they never weed their gardens, they just clip the weeds short, thus the weeds themselves are the living mulch. But my own experience and tests show that isn't quite right. The grasses and clovers compete too aggressively. Even the weeds. The test veggies that I grew using these living mulches did quite poorly compared to the control plants grown without the living mulch. Thus my own conclusion......I won't use grasses or clovers as living mulches. 

I believe in shading the soil surface for a number of reasons. Thus I've been interested in various mulching techniques. Presently I use grass clippings, but I've wondered if I could use something for a living mulch that could take over the shading task after the clippings start decomposing. I reasoned that the living mulch would have to be something that would spread and fill in the space. Be long enough lived to survive until the main crop was ready for harvest. Not be an aggressive feeder. Not have an aggressive surface root system. Not grow in such a way that it would smother and kill that main crop. The main crop I am targeting is taro. Future experiments will test other main crops. 

Taro does not do well with competition. So grass and weeds need to be kept under control. It is a long season crop taking at least 9 months, often more. It is very responsive to nitrogen feeding at the right time but does not want over-feeding the rest of the time. And it wants moist, shaded soil. I've been growing it using grass clipping mulch, which has worked pretty well. But because the clippings decompose rapidly, they need to be refreshed monthly. That's a problem for taro since it doesn't like you to walk anywhere on its roots. Applying new mulch means that I step near the taro, thus stunting its growth potential. 

I finally considered trying sweet potatoes. While the tubers are ready for harvest 4-9 months, depending upon the variety, they can be left unharvested. Sweet potatoes don't form dense root mats. Their large leaves well shade the soil surface. I haven't found them to be heavy feeders, though the extra nitrogen won't kill them either. It sounded good so I gave them a try. But I wasn't sure if the vines would smother the taro.

Guess what. Taro and sweets to together pretty well. At least so far. I've chosen a variety that is a bunch type with moderate runners and good sized leaves. So the main tubers are right under the heart of the plant. By planting the sweet far enough away from the taro, I could harvest tubers without walking on the taro roots. And by directing the vines towards the taro, the sweets act as a living mulch. All sounds good in theory, but would it actually work. 

So I planted taro. For the first experiment I choose a taro variety that is a strong grower and tall. And I planted the sweet potato cuttings in a spot that I could access without damaging the taro roots, plus importantly, in a place where I could also access the taro to clean up dying leaves if needed. Well, so far the experiment has been a raging success. But it's only been going along a few months, thus I will reserve judgement to when the taro gets harvested. The taro has been growing strongly. The sweet potato vines have been spreading and covering the surface without climbing over the taro. I initially mulched with grass when I planted everything but have not added more grass mulch since. Very little grass or other weeds have grown through the vines. 

Next time I will plant more sweet potato cuttings so that I see faster ground coverage. And I will try several different taro varieties with several different sweets, looking for the best combinations. So far I haven't seen any negatives, but then this has been a rather wet year. Will this method also work for drier years? We'll see. 

Here's another combination, a less vigorous taro matched to a less aggressive sweet potato. I'm interested to see how they get along together.......

Grass Clippings

It turns out that the lawnmower is one of my really important gardening tools. It's never used in the actual garden itself, but it creates the material that is my favorite mulch : grass clippings.

Dry, brown clippings. Excellent for nest boxes and mulching.

In reality, I use grass clippings for more than just mulch. They are a major ingredient in compost, they are used as an edible litter in the chicken pen, plus I sometimes use dried clippings for lining the hens' nests.

Fresh green, and very wet, clippings great for the
compost pile. Also wonderful for the chickens.

Grass clippings make a nice garden mulch. They are easy to apply. I can control the thickness and get then into tight places. And they decompose as the soil microbes feed on them, thus creating food for the plants. Between crops, they are easy to till into the soil. And I can readily get more when I need them.

Mulch in the vegetable gardens. 

As a compost ingredient, they are easy to work with. Already finely chopped, they compost down quickly and are easy to mix with the other ingredients. I can choose to add very green clippings which are high in moisture and nitrogen. Or I can pick the clippings from overgrown pastures that  are mostly brown and quite dry. It all depends on what the compost pile needs.

Pineapple bed at the community garden. Mulch helps keep
the grass at bay.  

 The chickens love kicking around a pile of fresh clippings. They will end up eating a lot of it. And what they don't eat just adds to the pen litter. That pen litter is harvested weekly, sent thru the tumbler composters, and is ready to use as mulch in the garden in three weeks. Certain plants really respond well to this dressing, such as the kale, chard, collards, taro, and most greens.

Mulched areas have very little weeds. 

I harvest all my grass clippings from "clean" land, that is, land not treated with commercial chemicals. I have plenty of my own land that needs topping off ocassionally. In addition, my neighbor is really glad to have me come mow his acre anytime. I've actually had people offer their land for mulch harvesting, but presently I have all the land that I can handle.

I'm always asked about weed seeds. Don't I have problems? Quite honestly, not to date. Sometimes a patch of weeds will sprout in the garden, but I can either flip them over with a shovel, cut them with a scuffle hoe, or simply lay a thick layer of mulch over them. Seedlings are fairly easy to kill. But when I do have a trashcan full of seedy clippings, I normally direct that to the chicken pen so the girls can hunt out the seeds. They do a good job.

Putting Weeds to Work

I was always told to eliminate weeds. Pull them out, throw them away. I spray them dead. But after decades of battling them (and often losing), I've come to see weeds as a benefit. For real! Crazy, no?

Before I read Ruth Stout's gardening book, I aggressively battled weeds with all sorts of hoes, cultivators, and tillers. Every weekend I was out there chopping weeds. The garden looked good March thru June. July got real iffy. By August the weeds began to win. By September the battle was lost. It happened every year. Some years the battle was lost by mid-July. I only had one day a week to use for battling weeds back then, so maybe if I had had  more time the outcome would have been better. But I suspect not.

A pile of weeds ready for grinding up

Then because of Ruth Stout, I started using mulches. Things dramatically improved. Less weed problems in the areas I was able to get a thick mulch onto. 

Weeds make a nice mulch when ground up.

When I started this farm here in Hawaii, I was in desperate need of compost and mulch. Back in NJ one could always get the town or utilities to drop off truckloads of trees chippings. Landscapers were happy to dump their truckload of grass clippings. In autumn bags and bags of leaves were free for the taking. Stable operators were glad to have people come cart their manure and wood shavings piles away. The local sawmill dumped sawdust by the cart load by the roadway for people to take.  But here, things are different. No free green waste in abundance. (For a while the county dumped free green waste mulch in Waiohinu, but alas, no more.) Therefore the number one use for weeds for me is as green waste to be collected and chopped into mulch. 

Weeds seldom overcome the garden because of  the mulching. But along the driveway, around the rock wall, in the pastures and woods, and on the rocky areas weeds constantly regrow. This means that I have a nice source of green material that I can harvest whenever I need it. To me it is a crop, not a bane. I guess it's just a mental adjustment. Funny thing now is that during times of drought, I'm wishing that the weeds would grow! 

# 2 use for weeds: compost ingredient. No way, you're gonna say! Weed seeds! Well, if I properly manage the composting, weed seeds don't survive. I monitor the temperature of the piles and attempt to get them to a minimum of 165 with each turning. That seems to be sufficient. I simply don't have weeds sprouting out of my compost. If I see it happening, I know I did something very, very wrong. If I don't get the pile hot enough, then weed seeds will survive. The tricky part is getting the cooler outside sections turned over into the center so that material can also heat up. 

Certain weeds work out as animal fodder. The horse, sheep, and goat seek out certain plants that I call weeds. I watch the critters to see which ones they like. Those I allow to stay in the pastures in order to give the livestock variety. I don't know the names of most of those weeds, but I can identify them by sight. I've even purposely sown some of those weeds into the pastures, especially plantains. 

Some plants that are called weeds are edible. I've transplanted nasturtiums and purslane into the garden. I found them growing as weeds. Plantain is also edible, but I haven't tried it. 

Weeds in the garden can be very useful, so I don't try to eliminate them all. So the garden looks a little weedy. Who cares. The weeds I allow to remain serve a purpose as long as they don't over populate. Some serve as a trap crop for insect pests. For example, whitefly seems to infest nasturtiums long before they move to other crops. So the nasturtiums alert me to the problem so that I can take action. Usually just plucking the infested nasturtium plants is enough to knock the whitefly population way back.  Other weeds are very susceptible to mildew, alerting me to take action with the vegetable crops. Weeds can also tell me a little about the condition of the soil. If the new weed seedlings look lush,  things are most likely ok. But if they are spindly or off color, then I need to test the soil and make adjustments. I know that certain weeds thrive in spite of poor soil, but that isn't an issue. My garden soil is improved, so it just needs to be tweaked.