ONIONS

[gary350]

Today in middle TN we are at or very near the 1/2 way point of daylight and dark. Most of my onion plants have 7 to 9 leaves to grow as many leaves as possible. Harvest is usually about 1st week of June. I gave my plants high nitrogen plant food March 1st to yesterday 4/16/2025. Plants may be finished growing leaves. Today I reduce nitrogen and give plants P&K to grow larger bulbs. Wife has trouble slicing the very large onions. I planted about 300 onions, 1/2 were small plants, 1/2 were 7/8" diameter sets.

I decided I should go to the garden to double check onion plants. Onions grown from small plants are 50% smaller than onion grown from sets but they all have 7 to 9 leaves. Some people call sets = bulbs.

 

[Horatorbr]

Interesting observation, it is clear that you are serious about growing. The fact that the seedlings gave a greater result is quite logical, they have more starting resources. But if all the plants already have 7–9 leaves, then the basis for the formation of bulbs has already been laid.
I would also pay attention to the density of planting - if the onions grow too closely, they literally compete for space and nutrients, which is why the bulbs turn out smaller.
It is better to give them a little more space, even if it means thinning out some.
Your approach with reducing nitrogen also sounds right, now the main thing is to help the bulb gain mass, not to drive greens.

 

[Meadowlark]

... The fact that the seedlings gave a greater result is quite logical, they have more starting resources.

Welcome @Horatorbr

So even more logical that onions started from seed even more resources. Seed>>Seedling transplants>sets.

The only downside I have found direct seeding is it takes some effort to get proper spacing...but that effort yields lots of thinnings to eat.

My harvest is about three-four weeks away depending on weather. Bulbs have a lot of growing to do yet.

Onion row...

 

[Gunnar]

Yup.....as said above, I plant that close then start eating every other one when they get to green onion size to get them spaced right. Otherwise wind up with small onions.