GROWING ONIONS FROM SETS

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PLEASE DON’T CRY…

Onions are most easily grown from bulbs, or “sets”.  One bulb will produce one onion; it may be harvested early as a scallion or ‘green onion’, or allowed to mature into a full-sized cooking onion.   Smaller bulbs (diameter less than dime-sized) will give you more onions if purchased by the pound or scoop, and are less likely to ‘bolt’ (go to seed) prematurely. Bigger is not better!  Varieties used for sets will mature into more pungent onions than those grown from “slips” or plants. Onions may be grown from seed, rather than sets or plants, but will take 3 to 4 months to mature. Green onions  grown from sets will be ready to harvest in approximately 6 weeks. If you want large onions for cooking, plant the bulbs 10”-12” apart and just under the surface. Keep them watered, fertilized and gently cultivated to discourage weeds.

Growing: Onions grow best in a well-drained, loamy soil of moderate fertility.  They have shallow root systems, so must be weeded gently.  If growing onions for scallions, plant them close together; they do not need much space between them.  Planting in blocks rather than rows will utilize your garden space more efficiently.  If you want some onions for scallions and some to keep over the winter, pull them alternately so space is left between the ones staying in the ground. Keep onions well watered during droughts.

  • For Scallions: The part of the onion below ground will be white (if white onion sets are used), and the part above the ground will be green.  Both parts are edible but most people use only the white part.  Either plant the bulbs 2”-3” deep, or hill up the soil around the onions when they are 3”-4” tall, to give your onions a larger white part.  White sets are most often used for scallions, but any color will work.

  • For Yellow Onions: They keep their quality in cool storage longer than red or white ones.  Onions pulled young, for scallions, will be milder than those left to mature.  If an onion plant sends up a flower stalk, pull it and use it promptly.  It will deteriorate quickly.  If the top of the onion plant is knocked over, the bulb will stop growing.

Storing: Onions for winter storage should be harvested gently and then allowed to dry in a warm, airy spot for a few days.  Do not damage or remove the skin; it will protect the onion.  

FALL-PLANTED ONIONS FROM SETS

Onions are most often grown from bulbs, or “sets”, in the spring but can usually make a successful crop when fall planted.  One bulb will produce one onion; sets may be planted 2” apart if harvested as scallions or ‘green onions’, or 4”-6” apart if allowed to mature into a full-sized cooking onion.  You don’t need to plant in rows; a 1’x1’ square can grow 24 scallions!  Varieties used for sets will mature into more pungent onions than those grown from “slips” or plants. Green onions grown from sets will be ready to harvest in approximately 6 weeks.

Onions will tolerate cold, even freezing, temperatures for a short period. A floating row cover will give them some protection when young. If you have not harvested all your onions by late autumn, put a heavy layer of mulch over them and you may be able to winter them over for spring harvest. In Indiana, it’s best to plan to pull them out before winter since our winters are unpredictable in both temperature and snow covering (which insulates the ground).

Onions grow best in a well-drained, loamy soil of moderate fertility.  They have shallow root systems, so must be weeded gently.  If the top of the onion plant is knocked over, the bulb will stop growing.  Plant the bulbs 1”-1.5” below the soil surface; trim off any brown tips that show above ground when you plant, to discourage birds from pulling them up (they think the tips are worms!). Keep onions well watered during droughts. Fertilize before planting with a high nitrogen fertilizer such as blood meal or fish emulsion. Green onions do not keep well; eat and enjoy them soon after harvesting!