Growing onions (Allium cepa) at home is easy and rewarding for any home gardener. Onions are easy to grow and are a desired vegetable and staple cooking ingredient across the world. Still, many beginner gardeners have doubts about how to grow this plant. This article will explore how to grow onions at home in your backyard. We will look at the different onion varieties, planting season, and basically what is needed to grow onions successfully (and easily).
Onion Varieties
Choosing the correct onion variety for your region is essential. Different types have different flavors, uses, and growing requirements. Among several varieties, we find popular choices such as red onion, shallot, and potato onions. Meanwhile, the closest relatives of onions are garlic and chives. The variety of onion most commonly eaten is Allium cepa, the common onion, and many cultivars stem from this cepa group.
There are 4 main types of onions:
- Red onions
- White onions
- Yellow onions
- Bunching onions
Red onions are so called after their reddish outer skin, and often added raw to sandwiches and salads. Their flesh consists of white and reddish/purplish layers, which you may recall from eating salads or sandwiches. White onions are so called after their white outer and inner fleshy layers. They tend to be mild in taste and can be easily consumed raw. Yellow onions are so called after their yellow outer skin, and they tend to be sweet and ideal for cooking.
Finally, the bunching onions (Allium fistulosum) are those types of onions that never form a bulb unlike Allium cepa, and they are also called green onions or scallions. In taste, they are similar to other onions, except their leaves and stems are eaten instead of any bulb.
Breeders create multiple varieties to adapt the vegetable to a different type of climate, photoperiod, and other environmental characteristics. The photoperiod is vital for the success of onion cultivation, which is why there are varieties adapted to short, neutral, and long days.
Those long-day varieties are ideal for growing in summer, and those requiring short days are best for winter. Before obtaining seeds or bulbs for planting, you should find the variety best adapted to your particular region, time of year, and climate.
Short-day onions will start developing bulbs when sunlight increases to over 10 hours a day. Neutral-day varieties will develop bulbs when sunlight is over 12 hours a day. Long-day varieties will develop bulbs when sunlight is over 14 hours a day.
Planting Location
It all starts with selecting the best place to grow onions. Onion plants benefit from direct sunlight. You should plant your onions where they receive at least 6 hours of light on a daily basis.
Substrate
The substrate is essential for the good development of onion plants. The substrate must be well-drained, ensuring there is no sogginess around the roots, which could lead to bulb rot problems.
Onions benefit from organically rich soils rich in organic matter. Worm cast and cured manure are some soil supplements that can and should benefit this crop. In addition to complementing the level of organic matter, this substrate will help with drainage and fertilization.
Planting the Onions
Now that you’ve prepared the site and soil, it’s time to plant your onion plants.
Planting season
The ideal planting time depends on the chosen variety and the geographical location we are cultivating. Generally, the ideal is to sow onion plants during spring, when the photoperiod is increasing, as is the temperature.
There are numerous winter varieties (short days). These varieties are ideal in cold regions. In this case, the idea is to plant them in early autumn. When planting during cold months such as fall, ensure the soil is well-drained and not soggy. For fall planting, ensure that the onions are given 4-6 weeks of relatively warm conditions so that they can establish in the soil. Once winter arrives, they become dormant, but will arouse with the return of spring.
Note you can also harvest your onions even before they are mature, like in the case of spring onions, which are basically onions planted during fall and allowed to develop briefly during the winter season.
Planting
You can grow onions through seeds, seedlings, or bulbs. Bulbs and seedlings are ideal, as the plants grow quickly and uniformly, unlike seeds. As seedlings, onions can grow quite fast, and mature in less than 4 months.
Plant onion plants with a distance of around 4-6 inches between plants and up to 1 inch in the substrate. Don’t plant them too deep into the soil, because it can affect the development of the bulbs. If planted in rows, keep the rows at 12 inches apart. For onions, slightly acidic soil of around 6-7 pH is optimal.
Although most onions are sold as seedlings or sets, you can definitely grow onions from seed. It’s best to start the seeds indoors and then move them out to the garden. Start the seeds about 2 months away from the last frost date in your area. Simply use seed starting mix, and shallow containers. Place the seeds on the soil and cover them lightly, water them with a mist spray and cover the container. Place the container in a warm place above 70°C/21°C. The seeds should sprout in less than 2 weeks.
The seedlings should now be gradually “hardened” by placing them outside for a few hours each day while increasing the duration until they can withstand overnights outside. Be sure not to expose them to frosts, as onion seedlings are not frost hardy. Once they are strong enough (typically 2 months from sowing), transplant them into the garden.
Onion Plant Care
Watering
Onions are not good at taking up or storing water with their shallow roots, so ensure to water deeply whenever the soil is dry. To grow onions, remember these plants require a good amount of water to thrive.
Fertilization
To grow onions well, remember to feed them often. Onions are heavy feeders and require a large amount of nitrogen and potassium. Carry out frequent fertilization throughout their growing season, strictly following the manufacturer’s instructions. When planting, it is recommended to add an inch of compost to the soil before adding the seeds or seedlings.
Common Pests
Onions may get thrips, root maggots, or aphids, from time to time. Thrips and aphids will suck sap from the leaves, weakening the plant and damaging the leaves. Avoid planting onions near alfalfa or any grain crops, because thrips are often found there and will migrate over to your onion crops. A mixture of 4 teaspoons of neem oil and 2 teaspoons of dishwashing liquid in a gallon of water and sprayed onto your onion crops can get rid of thrips and aphids.
Meanwhile, onion root maggots can tunnel into the bulbs and damage them. Installing row covers early after planting can help prevent these pests from taking hold. Unfortunately, there isn’t any easy way to control root maggots once an infestation has taken hold, except to remove badly affected plants and applying insecticides to the soil around the root zone and the base of the plants. Also, onion maggot eggs cannot survive if soil temperatures get too hot (above 95°F/35°C), so they aren’t a problem in hot and dry summer months.
Harvesting
You can harvest your onions anytime you prefer, as spring onions or scallions. But if you want the bulb to be fully mature before harvesting, do it when the leaves wilt and turn yellow and the flower stalks come up, usually in late summer or early fall. When the leaves fall, it’s time to harvest. Pull up the onions in dry weather, shake off the soil, and hang them somewhere airy to dry. The neck just above the bulb will dry and shrivel away, “sealing” off the bulb, which helps preserve the bulb for longer.
Proper Storage
After harvesting, let the onions dry in the sun or shade for about 7-10 days to cure the outer skin. Clip the tops, remove any dirt, and store them in a cool, dry place, ideally in a mesh basket or jute bag, where they can receive good air circulation. Well-stored onions can last for several months. Generally, sweet onions store for the shortest time while pungent onions can keep for longer.
Health Benefits of Onions
Onions are renowned for their health benefits because they are loaded with enzymes and nutrients that are good for preventing cancer, diabetes, and promoting immunity and weight loss, among others. When cut, raw onions release a chemical, syn-propanethial-S-oxide, that irritates our eyes, causing us to tear up. This sulfur compound is a natural defense chemical for the onion, but it actually acts as a natural antibiotic as well!
