Growing Your Own Onions

This cool season crop is relatively hardy and easy to store after harvest. It is common to start with onion sets as they can be planted without worry of frost damage and have a higher success rate than transplants or seeds. “Sets” are partially grown onion bulbs. These sets are produced by planting onion seeds thickly; the crowding of the bulbs leads to competition for water and nutrients, so the resulting bulbs remain small. These small onion bulbs are harvested in late summer and dried for about a month to prevent future rotting. They are then stored until spring or shipped to the areas in which onions can be grown in the fall, such as Florida!

Planting Your Onions:

Onions thrive in raised beds or mounded rows that are at least 4 inches high. They prefer full sun, so start by selecting a location where they won’t be shaded out by neighboring plants. The soil should be well-drained, loose, and rich in nitrogen; if the soil is compact, you can amend it with nutrient rich aged compost or Michigan Peat. Onions are heavy feeders and require constant nourishment to grow as large as possible. You can mix in some high nitrogen fertilizer at the time of planting, but a preliminary soil test is always a great idea. Many like to keep their veggie garden as natural as possible; fortunately, there are many options for adding nitrogen organically! You can use composted manure, poultry manure, blood meal, fish emulsion, crab meal, feather meal, alfalfa meal, soybean meal, or cottonseed meal. Make sure to follow the instructions closely when using any type of fertilizer, as even organic fertilizers are capable of burning your plants when used incorrectly.

Plant your onion sets starting in mid-September and throughout the month of November; you may plant again from February until April. By planting them intermittently, you will be able to harvest fresh onions every few weeks as they reach maturity! Plant the sets about 1 inch deep, with 4 to 5 inches between each set, in rows that are about one foot apart; be sure not to plant them too deep, no more than one inch below the soil. If more than the bottom third of the bulb is underground, its growth may be restricted! To help prevent problems with disease or pests, you can practice crop rotation by planting your onions in a new location within the garden each season. This is generally a good idea for most vegetables, so try to avoid falling into the habit of planting each crop in the same location each year.

Caring for Your Onions:

To get big onion bulbs, fertilize with nitrogen every few weeks until the onions begin to push the soil away; at this time, you can stop applying fertilizer. Do not put the soil back around the top of the onions; it is best for the bulb to emerge above the soil. While consistent watering isn’t always necessary if mulch is used, extra water is known to produce sweeter onions. Just make sure that your soil is well-drained to prevent rotting! About one inch of water per week is usually sufficient, and you’ll want to make sure to water during droughts as onions are known to look healthy even when they are dry. If you notice any of your onions sending up flower stalks, cut the flowers back or go ahead and pull the onion. This is referred to as “bolting” and is a sign that the onion is done growing and ready to start focusing its energy on making seeds.

Harvesting Your Onions:

You’ll know that your onions are ready when the tops start to turn yellow and fall over. At this point, you can bend the tops down or stomp on them to hasten the ripening process! When the tops turn completely brown and your onions are ready, gently loosen the soil to encourage drying. After a few days, turn the onions up and allow them to cure on dry ground (make sure that rain isn’t expected). Always take care with your onions, as even the slightest damage might encourage rot. Allow the onions to dry for several weeks before storing in a root cellar or any other cool, dry storage area. You can spread them on a screen, off of the ground, to help them dry. Store the dried onion at 40 to 50 degrees F, with the stems braided or removed. In Florida, it is difficult to find a cool, dry area for storing onions, so you may have to use them relatively quickly after harvesting. This is why it’s a great idea to stagger your planting so you can stagger your harvest!