Onions are an essential crop for any garden, offering both culinary versatility and the satisfaction of a rewarding harvest. With their relatively simple growing requirements and excellent storage potential, onions are an excellent choice for gardeners of all levels. Whether you’re growing them from seed or sets, this guide will take you through the entire process, from sowing to harvesting.
Choosing Onion Varieties
Onions come in a variety of colors and flavors, with yellow, red, and white being the most common. White onions tend to be milder and larger, making them great for salads. You can find a wide range of onion varieties suited to different climates and growing conditions. For a detailed list and recommendations tailored to your specific location, consult a gardening planner, which can guide you in selecting varieties with optimal sowing and harvesting times.
Preparing the Growing Site
Onions thrive in full sun and well-drained soil enriched with organic matter such as compost or well-rotted manure. If your soil is heavy or prone to waterlogging, consider growing onions in raised beds or on mounds to improve drainage and prevent root rot.
Starting Onions Indoors
For an early start, sow onion seeds indoors in plug trays or pots. This method avoids the need for thinning and allows you to transplant seedlings later. Begin sowing in late winter to get a head start before the spring planting season.
Fill plug trays with seed-starting mix and sow 4 to 8 seeds per cell, covering them lightly with soil. Water gently to avoid disturbing the seeds. When the seedlings are large enough, transplant them into the prepared ground, spacing them 4 inches (10 cm) apart. This method minimizes root disturbance and gives your onions a strong start.
Direct Sowing Outdoors
You can also directly sow onion seeds outdoors in the spring once the soil is workable and has warmed up. Prepare the soil by raking it smooth, then create shallow seed drills about 1 cm deep and 30 cm apart. Sow the seeds thinly, cover lightly with soil, and water gently to settle them in. As the seedlings grow, thin them out gradually to allow enough space for the bulbs to develop properly. For smaller bulbs, space the seedlings about 5 cm apart; for larger bulbs, aim for 10 cm between each plant.
Covering your sowings with row covers or fleece during the early stages can help protect against cold weather and may reduce the risk of the plants bolting (flowering prematurely).
Growing Onions from Sets
Another option is to plant onion sets, which are small, partially grown bulbs that are easier and faster to plant than seeds. While sets offer convenience, they may not store as well as those grown from seeds and are more susceptible to bolting. However, heat-treated sets are available, offering better resistance to bolting.
Plant onion sets in mid-spring, once the soil has warmed up. Space them 5 to 10 cm apart, with the tips just peeking above the soil. In some regions, you can also plant sets in early autumn to get an earlier harvest the following year.
Caring for Onions
Onions are shallow-rooted and require consistent watering, especially during dry periods. Regularly check for weeds and remove them promptly, using a hoe between rows and hand weeding within the rows to avoid damaging the delicate roots. If you’ve transplanted onions from plug trays, you can leave them as is or thin them out to allow the remaining bulbs more space to grow.
Harvesting and Storing Onions
Onions are ready for harvest once most of the leaves have bent over. The bulbs will continue to grow and mature, turning golden and firm. Carefully lift the onions using a fork or trowel, being careful not to damage the bulbs.
To store onions, they need to be cured by drying. Place them in a well-ventilated area, such as a greenhouse or an airy shed, for two weeks. This drying process toughens the skin, helping the onions keep for longer. If you’re in a warm, dry climate, you may even leave the onions on the ground to dry out naturally.
Once cured, store your onions in nets, tie them into bundles, or create decorative braided strings. With proper curing, onions can last from mid-winter to spring, providing a long-lasting and reliable food source.
By following these steps, you’ll enjoy a successful onion harvest that’s easy to manage and rewarding to grow. Whether starting from seed, sets, or transplants, onions are a perfect addition to any home garden.