Low-maintenance and undemanding, shallots will produce a good crop in any well-drained, fertile soil in full sun. They need a long growing period, but can be interplanted with faster-growing crops to make best use of space. They come in various shapes, colours and sizes, with a sweet, tangy flavour, and can be used for cooking or pickling.
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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 plants have at this time, the better the bulb will be.
Sow shallot seeds in late winter and keep in a greenhouse at 10–16°C (50–60°F).
Sow five or six seeds per module, then thin out if necessary to three or four plants. Each seed will only produce one shallot bulb, so multi-seeded modules are a good way to produce a clump of bulbs. Harden off indoor-sown plants in spring, to acclimatise them to outdoor conditions, before transplanting into the ground.
Sow shallot seeds from early to mid-spring outdoors, once the soil is drier and beginning to warm up.
Sow the seeds thinly, in drills 1cm (½in) deep, spacing rows 20cm (8in) apart. Thin out first to 5cm (2in) and later to 10cm (4in). Closer planting will result in more bulbs and a heavier crop, but smaller bulbs
Watering and feeding
Water in prolonged dry spells every 14 days, and give an occasional feed with a general liquid fertiliser. But stop watering and feeding once the shallot 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. Alternatively, use dry poultry manure.
Weed 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.
Remove any flower stems as soon as they start to form, otherwise the plant’s energy will go into producing the flower, rather than swelling the bulbs.
Shallots can be started from seed or more usually from sets (immature bulbs). Sets are easier and quicker to grow, fare better in colder regions and are less likely to be attacked by some pests and diseases. Shallot sets also produce a cluster of bulbs, while seeds produce just one. Still, seed-raised plants are less likely to bolt (producing a flower rather than a bulb). To reduce the risk of bolting, choose heat-treated sets.
You’ll find a range of varieties available in garden centres and online, both as sets and seeds, including a choice of bulb shapes, sizes and colours. Look in particular for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in trials – see our list of AGM fruit and veg.
Shallots need a sunny, sheltered site with fertile, well-drained soil enriched with plenty of well-rotted manure or compost. They won’t do well on acid soil (below pH 6.5), so reduce acidity by applying lime in autumn and winter. Damp soil makes the crop more prone to fungal diseases.
They are best suited to growing in open ground, but you could grow a short row or two in a large, deep container or raised bed. They’re not suitable for growing bags.
Planting shallot sets
Shallot sets (immature bulbs) are readily available in early spring and late summer in garden centres and from online suppliers.
Shallots have a limited root system, so improving the soil with lots of organic matter before planting is invaluable. Apply a bucketful of well-rotted manure or garden compost per square metre/yard. This will help add nutrients, improve the soil structure and hold moisture in the soil. Avoid using fresh manure. Also apply a high potassium general fertiliser, such as Vitax Q4, at a rate of one handful per square metre/yard.
Sets are generally planted in spring, from mid-March to mid-April. Plant them 2cm (¾in) deep in drills or gently push them individually into loose soil, so the tip is just showing at the surface. Space them 15–20cm (6–8in) apart, in rows 30–45cm (12–18in) apart. Firm the soil around the sets and water well.
Some cultivars are suitable for planting in late October to mid-March these are less sensitive to cold, which would otherwise cause bolting. Autumn planting is not suitable in heavy soils prone to waterlogging, as the crop is more likely to succumb to disease.
Birds can be a problem lifting newly planted sets, so cover with fleece until they’ve rooted in. Another planting option is to cover the ground with black weed-suppressing membrane, then plant the sets through slits. There is then no need for weeding, which both saves time and avoids any accidental damage to the bulbs when hoeing.
Shallots usually ripen in mid- to late summer. Yellowing and toppling of the foliage is an indication they are ready for harvesting. Lift the bulbs before the foliage dies down completely.
Use a hand fork to gently lever the clusters of bulbs out of the ground, taking care not to bruise them, as this could lead to rotting in storage. Carefully separate the clusters into individual bulbs. The bulbs can either be used straight away or dried and stored for later use.
Shallots that were planted or sown in spring can be stored well into the following spring, while autumn-planted sets only store until early winter.
Dry out the bulbs fully before storing. Lay them out in a single layer on a wire rack or slatted crates placed upside-down. Leave them outdoors in full sun to ripen for about two weeks or in a greenhouse or well-ventilated shed if the weather is wet.
When ready for storage, all the foliage should be dry and papery. Only store perfect, undamaged bulbs. Place the bulbs in net bags or trays in a single layer and store somewhere light, cool, dry and well-ventilated. Storing in the dark encourages sprouting.
Onion white rot
A soil-borne fungus that can cause yellowing and wilting of the foliage above ground, while rotting the roots and invading the bulb beneath the soil. A white fluffy fungus appears on the base of the bulb and later becomes covered in small, round black structures.
There is no chemical cure for onion white rot when it is the soil. It is important to avoid introduction to previously clean sites. It is transported in contaminated soil, for example on tools or on muddy footwear. Take particular care in areas where cross contamination can occur easily, for example on allotments.
Onion downy mildew
A fungal disease that damages foliage and bulbs, resulting in poor yields. It is a particular problem in damp conditions.
Avoid problems by make sure there is plenty of light and air around plants by sowing or planting at correct spacings, and by regular weeding. Avoid overhead watering if possible. Infected leaves can be removed.
This is a fungal disease causing bright yellow spots on the leaves. It is often worse in long, wet spells.
Mild attacks of rust won’t harm the plant, but serious infections may cause leaves to shrivel and affect yield. There is no control for rust once you have the infection. Make sure you don’t crowd plants, as this increases humidity and increases the likelihood of infection. Dispose of any badly affected plant material, and don’t grow garlic, leeks or onions in the same spot for three years.
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