Home GardenOrganic Vegetables Nutrient Dense and Pungent: The Onion

Nutrient Dense and Pungent: The Onion

by a Friendly Gardener

History sings with the benefits of the onion. As far back as the Middle Ages, it was believed that onions could cure headaches and snakebites, even baldness. Cough syrup was made by steeping onions in honey. Children had wounds treated with onion paste, and slices of onion positioned on the soles of feet were supposed to bring down a fever. Eating an onion before bedtime was believed to break the common cold by sunrise. Whether true or not, onions have rightfully earned their place in folklore, on the table, and in your garden.

Known botanically as the Allium cepa, the onion is a member of the Liliaceae family and as such is related to garlic, leeks, and chives. This family of vegetables is characterized by pungent flavors, and they are used in numerous cuisines worldwide. The onion can be found in a variety of shapes, sizes, and colors, and can range in. taste from juicy sweet to quite sharp.

Apart from culinary use, onions, as history indicates, are believed to have medicinal benefits. A cup of diced onions contains over 13% of the daily vitamin C requirement. Research has indicated that consumption of onions reduces the risk of cancer, especially those of the stomach and colon. And this tasty vegetable contains along with vitamin C, manganese, and vitamin B-6. They also offer mini doses of iron, magnesium, potassium, phosphate, calcium, sulfur, folate, and quercetin. Plus onion will add flavor without extra calories, sodium, or fat.


Cultivating Onions

Growing onions in raised beds

This is a cool-season crop, so spring and fall are the times to plant. They grow well in containers, raised rows, or raised soil beds and they can be grown from seed or sets. Sets are small onion bulbs that are sold in nurseries or garden centers for cultivating. Once sets are planted, your bulb will develop to a mature size in approximately 13 to 14 weeks.

An onion set should measure no larger than ¾-inch in diameter when purchasing for planting. Larger sets may bolt to flower. The onion will not cause frost worry, so go ahead and plant them.  They can be cultivated as an annual in USDA hardiness zones 5 to 10. You can also start your onion crop from seed.

Companion plants for onions include carrots, strawberries, dill, lettuce, as well as a few more.


When to Plant

If you decide to start from seed, begin your seeds indoors six weeks before you intend to transplant them. Seeds will require temperatures of at least 50°F. to germinate. In regions with a traditional winter season, plant sets as soon as your ground soil is workable which should be March or April or when temps no longer go below 30°F.

Fall crops need a month to six weeks of warmer temps to get established. They will then go dormant in winter but be awake and ready when next spring rolls around.


How to Plant

Onion growing in soil

Your onion crop requires full sunlight exposure with no shade from trees or other plants. The more sun there is, the larger the bulb will grow.

Soil needs to be loose, well-draining, and fertile. Know that heavy, clay-like, compacted, or rocky soil will negatively influence the development of the bulbs. Before planting, till the soil and when preparing your rows, add a half-inch of compost to the bottom of rows before beginning planting. For heavier soil types, add in matured compost to improve soil quality and texture. Be sure to use crop rotation when planting onions for more than one season.

Onion sets with a diameter of ¾-inch should be planted from two to six inches apart. If you are doing larger transplants, they must be spaced at least five inches apart. Rows should be distanced a foot to a foot and a half from one another. Position bulbs with the pointed end upward and do not plant bulbs too deep. They should be no more than an inch below the soil surface.


Onion Care

Red onions to eat

The first thing to keep in mind is that onions are very heavy feeders and require quite a bit of nourishment for bulbs to develop well.

Fertilize your crop every several weeks with nitrogen to improve bulb growth. End fertilizing when bulbs begin to push back the soil. Do not return the soil to the onions, because bulbs need to emerge.

Once the development of bulbs is apparent, mulch your crop with a half-inch of straw, shredded leaves, or hay. This will aid in suppressing weeds and retaining moisture, however, do not cover your emerging onions. If you mulch, your onions will not need extra watering. An inch of water weekly, including rain, will suffice. If you prefer that your onions be sweeter, you can water more. Onions have a healthy appearance which can fool home gardeners. If your area has a drought, water even if the onions do not appear to need water. This will impede bolting or flowering by the plants.


Harvesting Your Onion Crop

Harvested onions in a container

Pull out any onion bulbs that feature flower stalks. When flower stalks appear, the onion has ceased to grow and will not store well, so use it for cooking within days.

Onion crops planted in the spring should be ready for harvest in the middle of summer. Foliage tops will turn yellow and begin to droop. You can bend down these tops and stomp on leaves to accelerate the ripening process. Also, loosen the soil around the bulbs to promote drying. When the tops turn brown, pull out your onions gently as bruising encourages rot to set in. Your crop will need to be harvested by the end of summer and in dry conditions. Onions harvested wet will not store well for you and can begin to rot. Onions that are too mature, may spoil in the fall climate.


Storing Onions

Red onions

Roots and tops of harvested onion should be cut back to about an inch or two. You can avoid cutting tops if you plan on braiding your onions together. Onions should settle or cure for several days on the dry ground in good weather, or in a garage or similar where protected.

Once the onions have cured, you can hang them in a mesh bag, braid and hang them, or place them in a box in two layers. They should be stored in a well-ventilated, cool area with a temperature measuring between 40° to 60°F. Avoid the refrigerator because it is too humid. Keep an eye out for rotting or sprouting. Any onions with rot or sprouts should be removed.

Never store your onions with pears or apples that release ethylene gas that will disturb dormancy, and the pungent odor may ruin the taste of fruit as well as potatoes when stored together. Sweet onions store for less time than the pungent varieties because they have higher water content and will not store as well.


Pests, Diseases, and Problems

Onion maggots will take up residence given the chance. You can avoid these pests by covering your crop with mesh netting. These maggots like to lay eggs at the base. Good fine netting should prevent this from happening. If you have dry weather, they most likely will not visit as maggots prefer rainy weather.

Ting insects called thrips may look to your onion crop for food and lodging. Shake an onion top against a piece of white paper. If tiny tan-colored dots appear, you’ve got thrips. Using an organic insecticidal soap, spray your plants two times with a pause of three days in between. This should kill and eliminate the pests.

Onion bulbs may split if the soil remains too dry during development. If, on the other hand, the soil is too wet, bulb rot may set in.


Onion Varieties

Red onion

There are three classifications for onion varieties:

  • Long-day
  • Short-day
  • Day-Neutral

The difference between long and short-day varieties depends on the region where they are grown.  Day Neutral varieties can be grown anywhere without difficulty. Long-day varieties should be cultivated north of the 36th parallel and short-day varieties south of this parallel.


Long-Day Onions

  • Yellow Sweet Spanish (large, round, and yellow-white)
  • Red Wethersfield (flat bulbs, red-skinned with white flesh)
  • First Edition (creamy yellow and flavorful)
  • Red Florence (bulbs will be oblong in shape)


Short-Day Onions

  • Red Burgundy (red-skinned with white flesh, sweet-tasting)
  • White Bermuda (mild with thick, flat white bulbs)
  • Crystal Wax White Bermuda (when harvested small, it is ideal for pickling)


Day-Neutral Onions

  • Candy (golden, thick jumbo-sized bulbs)
  • Red Stockton (large white flesh with red rings)
  • Super Star (sweet, large, and white)


Are Onions Toxic?

Cut up red onion

Yes, onions are toxic to pets as they contain N-propyl disulfide. Onions can be the cause of red blood cell breakdown. Symptoms include bloody urine, vomiting, weakness, panting, and an accelerated heartbeat.


Can a Sprouted Onion Be Used for Planting?

Yes, but not for onions, you’ll get sprouts, that are tasty all the same and can be used in cooking.

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