I haven't fertilized the vines since the initial soil prep. Since the vines were growing well and looked a nice green, I choose not to add fertilizer. The only thing I've done is mulch them with rather stemy grass clippings. So I don't think that too much nitrogen is the problem. We've had enough rain that should have leeched out excess nitrogen.
I've been looking for signs of disease and pests. No mildew yet. The leaves and stems seem to be fine. I'm not ready to dig up the plants just check the roots. I know that I have rootknot nematode here, but the plants look too vigorous for that to be the cause.
Pollination problem? Perhaps. I was under the impression that limas are self pollinating, but is that true for this variety? Don't know. More basic, are the plants producing viable pollen? Don't know that either. But I can say that I haven't seen any bees visiting the flowers. The hive is less than 50' away and the girls are ignoring the lima vines.
Is this normal for this variety? I discovered that fava beans produced lots of flowers for weeks before they started producing flowers that set pods. Could this be the same situation for this lima variety? Could there be a minimum age factor?
Or could there be an environmental trigger that's missing. It's been fairly wet this year with not much strong sun. We've had hot days (hot for me is over 83° F) but not consistently hot. What is it that limas need to trigger pod production?
Perhaps a soil nutrient deficiency? If things don't happen soon, maybe I'll send off a soil sample.
I don't know of any local gardeners growing this lima under conditions similar to what I have on this farm. So I'm sadly lacking advice from successful lima growers. I guess I'll just have to keep experimenting and see what comes.