hi ms nature, I picked Copra because it keeps extremely well; so it will still be solid to plant early next spring. I do not expect that either Copra or Ailsa Craig would be hardy this far north; so I don't intend to plant my sets this fall. I would have some doubts that Ailsa Craig would keep long enough to get to next spring, but I know that Copra will, since I have done this before - replanting small Copra bulbs to grow on another year; I have not had a bolting problem from them yet either. You might have to plant the Ailsa Craig sets under lights, if they sprout too early which is actually quite likely. I would not expect them to winter over from a fall planting as far north as your and my gardens are, unless we have an exceptionally mild, snowy, and short winter. The key is as early as you can work your garden and plant as shallow as possible. Here in Minneapolis, I have squirrels that bury peanuts and walnuts in newly dug earth; so I cover newly planted beds with chicken wire, until there is a good sprout, and the bed has settled. I intend to also plant my multipliers next spring too. I know that works because that was done in my mother's garden, too, for decades.

It might happen if the wild onions have already flowered and set seed. Otherwise, no, it shouldn't be a problem. We have wild onions in some of our pastures and when I mow them in spring, I add those clippings (before the onions flower) to my garden mulch and I don't have a problem with wild onions popping up in the garden.

I've done it with one of the landscape cloth type mulches. It really kept the weeds down and I was really happy with that part of it. I watered with soaker hoses laid down on top of the landscape fabric (which also had a couple of inches of old hay on top of it), with one hose in between every two rows of onions. It worked well enough. At harvest time, you either have to cut the holes in the mulch material larger so you can pull the onions out through the holes (my holes were just X's cut in the mulching material, or lift the whole sheet of mulch so you can pull the onions. You still have to deal with weeds that pop up directly beside the onions, but that's nothing compared to how many winter seeds, in particular, sprout in newly planted onion beds. Bruce Frasier wrote about using plastic mulching long ago in one of the Dixondale newsletters, and if he says it can be done successfully, then it can be done. I think lots of commercial growers do it. I only did it for a handful of years. I found that I prefer to use a pre-emergent (corn gluten meal) at planting time and then just hand-weed what little bit of weeds sprout. By the time the pre-emergent is losing its effectiveness, my onions have made some good growth and I just put another layer of mulch on. My first later of mulch is usually about a half-inch of compost. Then I put on about an inch of old, spoiled hay. Then, as the onions enlarge, I add a layer of grass clippings. If the mulch thins out or weeds stop popping through, I add more mulch. I like using organic matter more than plastic because the organic matter decomposes and enriches the soil. Having said that, though, there's certainly nothing wrong with using plastic mulch. It works fine. I am not sure how well it would work in a very wet year. Since I have heavy clay, I always worried that the plastic might hold in too much moisture in a wet year, but we don't often have wet years here at our place, so I worried for nothing. I did love how the mulching material reduced erosion. I garden on a slope. There is not much flat land in my garden at all, so erosion can be an issue and the plastic certainly prevented much of that from happening.

I have found, and read, that onions will sprout less bulb and more green the deeper it is planted. I grew long-day onions last year and harvested some 2" - 2 1/2" onions. The previous year when I had them a bit deeper, they were all greens and scarcely any bulb. The caution of rot is a good idea in that we have had a lot more rain this year than in others. I will pull away the clippings and let things dru out a bit.