Are you growing onions from onion sets? Do they send up seed stalks or do the tops fall over earlier than you think they should? Do you get onions about pearl onion size, but want bigger ones?
With an understanding of how onions grow it’s possible to get better results.
Understanding What an Onion Set Is
Onion sets are small onion bulbs produced from seeds the previous year. Since they’re last years onions, their “job” this year is to make seed. That makes them very prone to stalking and setting seed.
Mainly Sets Offered in Local Feed and Seeds
When I first started gardening 33 years ago, sets and seed were the only way onions were offered by the local feed and seed stores. Because of that, I thought they were the only ways onions were grown. And since I thought of seed as being too difficult, sets seemed the easy way to go.
It was only after about 5 years of growing onions from sets that I discovered you get bigger and better onions with transplants. (Transplants are a small onion raised from seed the same year you plant them.)
What Accounts for Most of the Problems Gardeners Experience with Sets
I never remember seeing any information along with the onions in the store other than the price. Most of the time seed catalogs give information about the sets they offer. But, if you don’t know much about onions you don’t pick up on the information you need.
And this lack of information (or knowledge) probably accounts for most of the problems that people have when growing sets.
Understand this Fundamental Onion Fact
To form bulbs, onions require a certain number of daylight hours. Different varieties require different day lengths. And the North gets more daylight than the South.
A variety that takes 14 to 16 hours of daylight before it can start to bulb can only be grown to maturity by northern growers. They are called Long Day Onions.
Intermediate-Day Onions start the bulbing process when daylight reaches 12 to 14 hours. These onions will perform well in most parts of the country except the extreme southern part.
Varieties of Short Day onions start bulbing when daylight reaches 10 to 12 hours. These varieties are the ones that Southern gardeners must have to be successful.
A gardener in the South who never gets more than 10 to 12 hours of daylight will not be able to get large bulbed onions from varieties that require more than 12 hours of daylight to bulb.
Dixondale Farms in Texas, probably THE largest supplier of onion transplants, has a nice map on their website that shows this.
Now you know why it’s important to know if your sets are Long Day or Short Day Onions. You want to make sure you have enough daylight hours to bring them to maturity.
The Size of the Onion Set is Important
When you buy your sets separate them into small and large. The ones that will make the larger onions are about the size of a marble or a dime. Anything larger than that will produce only spring onions.
Planting Depth is Important
Plant your onions about one inch deep. This is true for sets and for transplants. If you plant too deeply the onions won’t bulb and you’ll just get a straight stalk.
More space equals larger onions. So if large is your goal you will want to space your onions at least 3 or 4 inches apart.
When to Harvest
- Onions can be pulled and eaten anytime you want.
- When onion tops fall over by themselves, they’re finished. They won’t grow any more. Harvest and eat or harvest and cure.
- If the onion makes a hard/hollow stalk and forms the bulb which will become the seed head, they are finished and won’t grow much more. Harvest and eat. They will not cure.
Plant early enough to give your onions time to develop good roots and grow some before daylight hours trigger bulbing. Otherwise, you’ll get very small onions.
If You Plan to Save Seed
If your onions are hybrid then the seed will not come back true. In other words, you may get an entirely different onion than the one from which you harvested the seed.
Open pollinated and heirloom types breed true.
Know if your variety is hybrid or OP/heirloom.
Weather and rain can also effect bulb size. You can’t control that. But armed with the information above you should be able to get much better results and some good sized onions from your sets.
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