How to grow shallots

Shallots can be started from seed or more usually from sets (immature bulbs). Each set produces a cluster of new bulbs, whereas a seed produces just one.
 
Sets are easier and quicker to grow, fare better in colder regions and are less likely to be attacked by certain pests and diseases. However, they are more expensive and must be planted soon after buying. Choose heat-treated sets to reduce the risk of boltin (flowering).
 
Seeds are cheaper to buy and a packet should last several years. Seed-raised plants are less likely to bolt, but grow more slowly and need more attention in the early stages.

Although usually grown from sets, shallots can be grown from seed, sown either indoors or outside. Seed is cheaper to buy, but slower to grow and the seedlings need more careful attention, however seed-grown plants can be less susceptible to bolting (flowering).

To ensure a good crop, seed-raised plants must be growing strongly by late spring, as the lengthening days trigger the formation of bulbs – the more leaves that plants have at this time, the better the bulbs will be.

Sow shallot seeds in late winter into modular trays filled with seed compost. Sow five or six seeds per module, then thin out if necessary to three or four seedlings. Each seed will only produce one shallot bulb, so multi-seeded modules are a good way to produce a clump of bulbs.  
 
After sowing, place the tray in a heated propagator in a greenhouse, or on a warm sunny windowsill, at 10–16°C (50–60°F). Seedlings should appear within a couple of weeks. Remove from the propagator, place in a warm bright spot and keep the compost moist.

In spring, harden off indoor-sown plants to acclimatise them to outdoor conditions, before planting into the ground or a large container. Don’t split up multi-seeded modules into individual plants – just plant them as they are, to form a clump of bulbs. Space the clumps 15–20cm (6–8in) apart, in rows 30–45cm (12–18in) apart. Gently firm the soil around the seedlings and water well.

Water shallots in prolonged dry spells every fortnight, but stop watering once the bulbs have swollen in mid-summer. Watering spring-planted crops after mid-summer can mean they store less successfully.
 
Try to avoid overhead watering, as this can encourage fungal diseases.

In late winter, give autumn-planted shallots a nitrogen-rich fertiliser, such as sulphate of ammonia, at a rate of 35g (1oz) per square metre/yard. This not only enhances growth but can also suppress premature flowering (bolting). Alternatively, use dry poultry manure.
 
You can also give an occasional feed with a general liquid fertiliser, from spring to mid-summer.

Weed between plants regularly, taking care not to damage the bulbs or foliage if using a hoe – ideally, weed by hand.
 
As the leaves cast little shade, weeds grow readily and can soon swamp the crop, which would reduce the plants’ growth and subsequent bulb size.
 
To avoid the need for weeding, consider planting through weed-suppressing membrane.

Remove any flower stems as soon as they start to form (bolting), otherwise the plant’s energy will go into producing the flower, rather than swelling the bulbs. It also means the bulbs won’t store well.