Easy to grow and indispensable in the kitchen, onions are a good crop for beginners. Try your hand at raising sweet-tasting shallots and red-skinned onions, as well as the more traditional garden varieties, with this simple guide.
How to Grow
Onions are undemanding to grow but prefer a sunny, sheltered spot and well-drained soil, enriched with organic matter. They can be raised from seed sown in the spring, or you can give yourself a head start and buy “sets,” which are small bulbs to plant outside. Sow seed under cover into modules, and harden off the seedlings before planting them out in late spring. They can also be sown directly outside in drills in late spring, once the soil has warmed up, giving a useful late summer harvest.
Plant onion sets directly outside from early to mid-spring, 2–4 inches (5–10 cm) apart in rows 12 inches (30 cm) apart, pushing them into the soil with the tips uppermost until just protruding. Shallots grow too slowly from seed, so plant sets from late winter to early spring, 6in (15cm) apart in rows 12in (30cm) apart.
Onions and shallots need little attention except regular watering and weeding. Once the leaves start to turn brown, bend over the tops to help ripen the bulbs. When ready in summer, lift the bulbs with a fork, then dry and store.
Types of Onions and Shallots
- Red onions are generally smaller and sweeter than traditional brown-skinned onions and can be finely sliced and eaten raw. Try ‘Hyred’ F1, ‘Kamal’, ‘Red Baron’ and ‘Red Brunswick’.
- Brown onions have the strongest, most pungent flavor, and there are many
to choose from. Some can be harvested small for pickling. Try Ailsa Craig’, ‘Bedfordshire’, ‘Golden Bear’, ‘Setton’ F1 and ‘Sturon’ varieties.
- Round shallots need a long season and grow as small clumps, not individual bulbs. They are richer and sweeter tasting than onions. Try ‘Delvad’, ‘Golden Gourmet’, ‘Pikant’, ‘Prisma’ F1 and ‘Red Gourmet’ varieties.
- French shallots are similar in flavor and growth pattern to the round ones, but are easier to chop because of their elongated shape. Try ‘Jermor’, ‘Longor’, ‘Mikor’, ‘Pesandor’, ‘Vigarmor’ and ‘Zebrune’ varieties.
Sometimes called Japanese or “overwintering” onions, these are hardy varieties that grow through the winter to harvest in midsummer. Sow seed in the fall directly into a bed outside, or plant sets mid- to late fall into well-drained soil. Plant more closely than summer varieties since some will be lost during the winter. Feed the plants in winter with a nitrogen-rich granular fertilizer, and thin them out in the spring. This technique can only be used with hardy onions—others bolt in cold weather.
Storing Onions and Shallots
Harvest onions and shallots when their leaves turn yellow and fall over;
in midsummer for shallots, early to late summer for onions. Once
lifted, lay the bulbs on the soil in the sun to dry out, ideally on wire
mesh to allow air to circulate around them. If the weather is wet, dry
the bulbs in a sunny, warm spot indoors. When the skins have turned
papery, remove the leaves and any soil, and store them somewhere light
and well ventilated. Lay them out in rows, braid them into ropes using
their leaves, or store them in nets.
Watch Out for These Pests and Diseases
Onion fly larvae eat the roots and bulbs of onions and shallots, causing plants to yellow, wilt, and even die. Rake soil to expose pupae to birds, and cover young plants with garden fabric.
Onion white rot can also cause foliage to yellow and wilt, and white mold
appears on the base of bulbs, which rot. Destroy infected plants, and
rotate crops annually.
Growing Green Onions
Fast-growing green onions are a staple of summer salads and Asian
cooking and are ready to harvest 4–6 weeks after sowing. They prefer
fertile, well-drained soil and a sunny site. Sow in succession all
summer from early spring, every two weeks, into pots or shallow drills, 3/4 inch (2 cm) deep, 12 inches (30 cm) apart, allowing 1/2 inch (1cm) between them. Weed
regularly, and water in dry conditions. Harvest when 6 inches (15 cm) high
and of your preferred thickness.