If you catch the flower stock early enough the onions seem to still bulb up fine. By early I mean before the flower head even begins to form. It is hard though to tell the difference between a normal onion leaf and the flower stalk other than by feeling them to find the thicker, more rigid one.

I don't bother trying to Id them, I usually just cut off the flower stocks when and if I notice them. Sometimes I will just go ahead and harvest a bolter or 2 if I know I am going to need some onions for cooking. As you probably already know they don't store very well.

I think you grow from Dixondale starts. Supposedly it is the thicker, more mature seedlings that have more of a tendency to bolt. This is only anecdotal and I myself have never tried to isolate the thicker seedlings to confirm it. I usually only get maybe 5% that bolt and variety doesn't seem to make much of a difference.

My dixondale plants are just starting to show good growth after planting out 4 weeks ago. I need to throw some urea on them today before we get rain overnight. The garlic could use it as well.

My 1015s were Dixondale. The Red Creole I seeded myself, though I guess I could have gotten them from Dixondale. But catching the flower stalk early seems like a sensible strategy that fits with my experience.

That is, by the way, a terrific idea to just feel the stems. If you see a stem that looks stalk-like, just grab it. The flower stalks are solid, and the regular onion leaves are hollow. They feel very different. I chased down a couple of other bolting stalks doing that.

I'm growing long day Dixondale onion seedlings this year for the first time. I planted them out around April 1st. We just got snow here in Mass. so the little onions are sitting out there covered by bit of snow. I'm worried about them bolting due to cold temperature stress or whatever other reason they might decide to bolt.

At what point do the flower stalks start to appear? Is it about the same time that they start to form bulbs?

PS Thanks for the tip on how to identify a flower stalk!

A few of mine started to bolt long after they started to form bulbs. Right now, my 1015s are a week or two away from harvest, and I'm seeing a few buds on them. My Red Creoles have more buds, and that is consistent with what Dixondale says about them, that they are less resistant to bolting. I have no idea how long-days behave. This isn't that big a deal for me. Out of eighty or so short-day onions, I've pulled off about a dozen buds. But that's more than last year, when I only had a couple.

Cold weather aside, just about any plant puts out flowers if it thinks it's about to die. In the case of onions with mature bulbs, they know that's about to happen, and they have the foliage-power to support seed production, so they go for it. I have to suspect that little onions wouldn't bolt, because there is no way that they could actually mature seeds.

BTW, if you have a Dixondale onion-specific question, don't hesitate to ask them. They provide great support, and when I have an onion question that I ask them, I usually get an informed response back in a day or two.

Since you are using transplants that have been overwintered, isn't it natural for biennial onions to flower in the Spring in their "second" year? I think the varieties have been selected for being slow to bolt, but you can't control the weather.

For long-day onions, that are intended to be planted in the spring, Dixondale plants them in the winter, and harvests the small plants in the early spring. That's not "overwintered", and it's not their second year. If it were their second year, they sure wouldn't still be tiny plants.

They are biennials, I thought you did plant them before Spring, they think it is their second year, time to flower, even if small, which is why they bolt. Dixondale admits that this happens, you are trying to trick the plants to make large bulbs, which is why you didn't plant seeds in the Spring. Just pull the ones that bolt first, or cut the flower off, I don't think there is any secret Dixondale is hiding.

Only a small percentage of my Dixondale onion starts bolt each year. I'm curious to see if the artic blast that south Texas (where Dixondale farms is located) had this winter will cause increased bolting. I bought my DD starts locally on March 11 so I'm pretty sure they were harvested after the cold blast in mid February

Sorry, Robert. Who are we talking about here? Terrene's were planted out in April 2021 (No year was given, but I have to assume that, because they are small). Mine were planted out in November 2020, and have been in the ground for five months. So it is the second year for neither. Onions don't use calendars, so they can't tell when 2020 changes to 2021.

But I agree that for onions that were kept in the ground for more than a year, they'd bolt like crazy.

My onions were in the ground and three months old when the arctic blast hit. So they were pretty large. I had tarps over them, and with the snow on top, they were quite flattened, but within a week or two they popped right back vertical. It is possible that the slightly larger number of onions that bolted in my set did so because of that unusual cold stress. It would also be interesting if the late-season long-day plants from Dixondale, which were small when the blast hit, were similarly stressed.

Dan - I will let you know in June when mine bulb up! Though mine are all intermediate day. Mine are going to go through another freeze at 27F overnight and 1-3" of snow on Tuesday and 30F on Wednesday. They are mostly at 4-6 leaves now at 5 weeks from transplant. I'm more concerned about the young leeks and lettuce but I can cover them easier.

My understanding is that onions have no trouble with light freezes, and can handle temps down to 10-15F or so. What we got here in mid-February was 5F, which was 7a weather in an 8a/9a region. They survived grandly after being covered with a tarp, and the fact that we got an insulating 6-inches of snow on top of that tarp helped. I was upset when I took the tarp off, and found all the onions perfectly horizontal. The tarp with the snow on top just pressed them flat. But two weeks later, as if by magic, they were all strong and vertical.

On reading about this, it seems that making plants want to seed by chilling them for an extended period of time is well understood, and very true for many plants, including onions. That's a process called vernalization. Nice writeup here ...

https://ipm.missouri.edu/MPG/2010/11/Why-Onions-Bolt-Failing-to-Bulb/index.cfm

Very interesting that once vernalized, onions can actually be de-vernalized by extended exposure to high temperatures. In fact, that kind of thing can happen around here, as we've already had 90F days.