With all produce, nothing compares to growing your own, and onions are no exception. Onions are a requisite ingredient in kitchens throughout the world. Some varieties are excellent raw, whether sliced on burgers, or chopped in cold salads. Others are preferred for cooking, because their more pungent flavor or firmer texture holds up better in heat or liquids. Luckily, there are varieties to suit all cuisines and preparations. And growing onions is a snap, if you follow some simple guidelines. Since most cooks use onions in nearly every meal, it's wise, if you have a sizable garden, to dedicate a lot of space to growing them.
Onions can be grown in most parts of the U.S., but each plant is intended for a specific type of growing region, based on the amount of sunlight per day. Determine your summer day length and choose from short day, intermediate day or long day varieties as recommended.
Sets, direct seeding, and transplanting are the three options for planting onions. Sets are like baby onions, planted from seed the previous year. Sets tolerate light frost and can be planted earlier than the last frost date, but they also have a shorter storage life after harvest. Onions planted from seed have a longer storage life, but they're slower to produce. For the earliest produce, start with transplants. Transplants also are prized for the best flavor and heartiest, largest bulbs.
If you're going to plant transplants, you can raise seedlings indoors 8 to 12 weeks before you plan to transplant in the garden. Or, you can buy transplants ready to transfer to your garden. Choose onion plants from a reputable grower who will provide you the healthiest onion plants to start with.
Onion plants can be transplanted about 4-weeks before your last spring frost date. They should be planted at a depth of around 1-inch, to support the plant and keep it from falling over. Space them 4-inches apart. Rows should be 8-inches apart.
Onions seem to attract weeds, so make sure you weed regularly. Keep soil watered, but don't let it get saturated, or the onions will rot. Adding compost in late spring will supply the onion plants all the fertilizer they will need. If you don’t have compost, apply Neptune’s Harvest Fish and Seaweed every 4-weeks.
Onions can be harvested and eaten at any stage in their growth. They're ripe when the tops start falling over and the bulbs have developed a papery skin. They're at their peak ripeness when most of the foliage has fallen over. If onions bolt, or go to seed, they'll develop a rigid center stem. It's best to just pull that onion and use it right away, as the bulb will stop growing anyway.
Harvest onions late in the summer. Pull up gently on the green foliage and lift the onions up. Allow them to dry out in the sun for a few hours each of a few days, bringing them indoors at night. This cures them and prepares them for storage in a dry, dark place with good ventilation where they'll keep over an entire winter, if conditions are maintained.
To store onions, make sure you have an area that will promote dormancy, with temperatures between 32 and 40 degrees. Onions will sprout at 40 degrees and higher. Do not store them in the same area as tomatoes or apples.