For a while I've been fussing with multiple onions, trying to learn to grow them well enough to harvest a crop. While they have been growing for me in Hawaii, it hasn't been without its issues.
First issue ..... Black aphids. These aphids seem to prefer these onions over any others that I have. I've tried several methods to control the aphids and have failed miserably. While I've been able to assert some control of this pest with the other onions (by harvesting early and rotating the beds), these multiples onions don't respond well to being transplanted every couple months and moved to a different location. Plus they produce (it's normal) a brown skin along the outside of the shank, which seems to be an excellent hiding spot for the aphids. The brown skin makes physically removing the aphids close to impossible. The onions quickly succumb to the aphid infestation.
(Above, rotted onions I removed today from the bed.)
Second major problem.....rot. The past 2 years has been very wet. While my regular onions seem to tolerate the extra rain ok, these multiplier onions do not. When a month is on the dry side, these onions perk up and grow really well and fast. But give them two weeks of rain and they start rotting. I think that if I were serious about wanting to grow them here, I'd have to put a plastic tunnel over them to keep the excess wet away from their roots.
Since regular onions grow well on my farm, I'm losing interest in these multiplier onions. Not the right variety for my location. Too much effort and attention needed to get a crop as compared to other onions. There is little advantage to my growing them since I can grow regular onions year around, they grow better and produce thicker, juicy, better tasting onions. While multiplier onions don't require propagation from seed (the propagate by division of the clump), I could produce my own onion seed if need be.