Now is the ideal time to plant onions in Tennessee. Onions are a cool season crop and prefer growing when the temperatures are cooler in the spring. They can pretty much be eaten throughout their entire growing process from the green leafy stage until they form a bulb.
Onions can be planted in one of three ways. Seeds are the cheapest means of planting onions, but they require more maintenance due to competing weeds. If you are planting your seeds inside to transplant later, then they need to be started at the beginning of January. I typically see them for sale by transplants or bulbs. Either of these methods are easier to work with since you can space them appropriately. Transplants and bulbs are planted 1-2” deep in the soil and 4-5” apart in the rows. Sometimes I will plant mine tighter and pull every other one for a green onion when we need one in the kitchen. This also helps the other onions left in the ground to develop a larger bulb.
There are three main types of onions and each area in the U.S. can require a different type to be successful. Long-day onions require daylengths of 14 or more hours per day in order to form a good bulb. Short-day onions are typically grown in the deep south and these typically won’t form large bulbs in the north. Intermediate-day onions are the most adaptable onions and they are grown throughout the middle section of the U.S. including Tennessee.
Harvesting onions depends on a lot of factors, but they can be harvested anytime you want. If you are wanting the dry onion bulbs then you harvest them when the tops fall over. I have seen people go through and break the necks over when they feel the onions have reached their full potential. Do not leave the mature bulbs in the garden too long because they can rot if left too long. After they are harvested, be sure to cure them somewhere out of the sun. This will help in the storing process and lengthen the time they can be stored.
I’ve with many types of onions in Tennessee, but my favorites are ‘Candy’, ‘Super Star’, and ‘Red Candy’. If you are looking for the Vidalia-type onion, look for one called ‘Granex’ because it is the one that is commonly grown in that section in Georgia.
As always, if you have any questions regarding any horticulture facet, feel free to contact Lucas Holman, UT Horticulture Extension Agent, Wilson County at 615-444-9584 or Lholman1@utk.edu.
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article submitted by Lucas Holman, UT Horticulture Extension Agent, Wilson County
