If you want to get bigger onions allow more room between onions. Six inches between each should do the trick.
Although this is an important key to getting bigger onions — keep in mind it’s not the only key.
- Different varieties grow to different sizes.
For example: In general, Copra – a great keeper – is not going to get any bigger than 3 to 4 inches across. Whereas Ailsa Craig – another long day variety — has the potential to get up to 8 inches across and weigh in at 6 pounds.
For great growth – onions also need:
- To be planted early enough to grow strong roots and more leaves before bulbing is triggered
- Soil high in organic matter
- Soil that drains well
- Mulch to keep the moisture in and the weeds down. (Onions don’t compete well with weeds.)
- Planting dept of only 1 inch
Overall — transplants (an onion seedling grown from seed this year) grow the best onions.
If you’re planting sets (little onion bulbs) — rather than transplants choose the small sets — about dime size. The smaller sets make the biggest onions.
(You might want to review my post Onion Sets What you Need to Know to Get Better Results)
What I do
I don’t have a lot of use for great big onions, so I usually plant mine about 3 to 4 inches apart. (I don’t use a ruler — I just go by eye.) And I get nice size onions and in spite of the fact I don’t set out to get great big ones — I do get a few.
Day length is critical
Day length is what triggers bulbing. Some onions take more day length than others to prompt this process. (If onions don’t bulb they can’t get big.)
To find out what day length onion you need visit this page of the Dixondale website.
Also — if you explore their site — remember they’re not organic. Also — as an organic home gardener — they give some advice I would not follow.
If you end up ordering from them — keep in mind some of their onions are from Monsanto owned companies. Just email and ask them. They’re very cooperative about telling you.
Just so You’ll Know
If you buy transplants from your local feed and seed store — they’ll be selling onions that are the correct day length for your area.
If you buy seeds — the seed companies don’t always tell you what the day length is. Do a little research online before you buy. If you live in the deep south and order onions for long days of the far north — those onions will not bulb for you because they won’t have enough day light hours to trigger bulbing in long day onions.
If you live about in the middle of the country like I do (Virginia) — almost all day lengths will do ok for you. I grow short day, intermediate, and long day onions. All do well.
If you’ve come across this information a bit too late and have already made some “imperfect” moves — just chalk it up to learning and move forward. The worse you can do is get some great spring onions or some small sized onions. Not such a bad consequence.
May all your onions be just the right size! 😉
Other Posts on Onions:
Organic gardening is easy, effective, efficient —- and it’s a lot healthier.
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