When I want to plant squash after onions, I grow the plants in pots so I have seedlings with 5-6 leaves as replacements. Bush beans, broccoli, cabbage and all the fall greens make good follow-ups for onions, which mature mid to late July here, a couple of weeks after garlic.

Onion sets do not do well here at 38th latitude, but I do use them for scallions. Seedlings do much better, both overwintering varieties and those started indoors in late winter.

The schedule you would follow to grow your own onion sets is about the same as for the overwintering onions, only with the winter onions you can leave them in the ground.

One year I planted the transplants I purchased from Lowe's. It was disappointing since the onions did not grow to large size. This year I will try the onion sets, or try to start from seeds over winter. I'll need to get heat mat for the seeds.

Do not know much about overwintering onion. When do you start seeds? in summer?

Onion (and leek) seeds don't need bottom heat so you won't need a heat mat for them.

As for onion sets, there are many posts on this forum and the Vegetable forum where people have reported disappointments with them. They have a tendency to bolt, rather than bulb.

And finally, planatus has mentioned in several posts about when to plant overwintering onions. The link below is just one.

Rodney

Here is a link that might be useful: Direct seeding onions in Fall in zone 5

I used to plant seeds to make onion sets, and was usually reasonably satisfied with the results. However, once I planted seeds in the fall to make seedlings to overwinter, I never went back to the sets for onion production. The seedlings look so tormented and delapidated over the winter outside, but they really do produce a much better onion for me the next spring than the sets did. I have tried planting a whole patch of onions in a small area, and then transplanting the seedlings in the Spring to their final growing spot. The results have been very good. A square foot of space in the fall garden will give me hundreds of small seedlings to plant the next spring. There is very little weeding, or other care needed. The fall planting looks like a little bit of lawn. I find that the seedlings are quite hardy, and I rarely lose any in transplanting. For me, the seedlings produce larger onions, with fewer bolting, and fewer with any rot issues. The seedlings are also less work for me, and a packet of seed, even an ounce, is not very expensive if I want a lot of onions.
Renais

I think I'll need to research more on over-wintering onions. Some folks mentioned this.

I planted some onion transplants purchased from the big stores. The results were not good. I guess they were planted maybe too late. Or the transplants were not of great quality.

It is too late for fall planting. I think I may be able to catch up with winter sowing the seeds indoors. Then I would try fall planting seeds.

Hi all;
I agree growing transplants from seeds in my zone 2b/3 is the only way I tried sets for years, but to grow the sweet onions and the storage onions I want I go the transplant route. I have been successful with Walla Walla, Candy, and Hendrix these are the varieties I have settled with the picture is a Walla Walla mid August harvest. planted on about may 15 {{gwi:368668}}

IF you grow your own sets you will have a much larger choice of varieties, but remember the sets have to store until the next spring; so that rules out short storage types and that eliminates many of the largest varieties. Really all you have to do to produce your own sets is plant them thick, remember you are shooting for very small first year bulbs, 3/4" and a little smaller are best .

Best results with sets is to plant the smallest ones, like 3/4" and under, and set them right at the surface. Many of the storage or cooking types will not get large like Candy or Sweet Spanish, but those larger, sweeter types do not store as well either. Stuttgarter and Ebenezeer are standard yellows for and/or from sets. I had very good results last year from Copra, where what I had were actually too big in the first place but did not have a single bolter. They did almost identically to the what I got from a bunch of plants I bought, with both ways turning out very well. I have come to really like Copra.

Growing up in NW Iowa in zone 4, all my family ever planted were the sets. Some bolting to be sure but not ever very many. My mother grew her own sets a couple of years in there, but most often a couple of bags of sets came home with the groceries some time early each spring.

Remember that sets you grow have to store until spring, which cuts down your options, and generally the smaller the set the less likely it is to bolt, provided it has a nice uniform growing season; so mulch once you get a good sprout to keep the soil uniformly moist and side dress the growing onions.

BTW sets are not an option at all for most of the big sweet onions. For most of them sets will simply not store well enough to last the winter.

Old Dutch;
I've seen seeds for Copra but up here in B.C. Canada, I've never seen Copra Sets. On the garden centre stands you only see (yellow onion sets, with no given name.) I find My Walla Walla keep until Dec. the Candy 'til Jan/Feb, and the Hendrix keep well into May. How long could you store Copra?
Chic.

It looks to me like Copra should store into the next summer at least, when well cured.

Normally they do not use hybrids for sets, I think it has to do with the extra cost of the seed against the return. Normally commercial yellow sets are either Stuttgarter or Ebenezer, and it may say right on the package or it may not. The variety of the white and red sets is usually not listed.

To get Copra sets you pretty much have to grow your own, but that is really little more than getting a tightly planted set of seed to sprout and then doing very little beyond a minimal weeding. You can produce a lot of sets in a very small space with very little effort.