No. 15
MULTIPLIER ONIONS & SHALLOTS
Allium cepa Aggregatum group
Family: Alliaceae
Multiplier onions and shallots seed saving guide also available here as a PDF document (289Kb)
Potato onions and shallots are very productive and easy to grow. For little effort you can get a return between three and eightfold a year, by weight. Shallots invariably form a cluster of new bulbs, often as many as 10 or 15 a cluster. Some throw up a flower stalk, but this should be removed as soon as it is noticed. Potato onions usually form a cluster, especially if they are large when planted, but sometimes a small bulb simply grows without multiplying.
Growing and Roguing
- Soil preparation should be as for other onions, with plenty of organic matter and a pH of between 6.5 and 7.0. The big decision is whether to plant in autumn or spring; each has advantages and disadvantages.
- Autumn planting usually gives a much better yield, often twice that of a spring planting. The risk is that your plants will be destroyed by severe frosts. Multiplier onions are very hardy and can survive down to -30°F.
- The best strategy is to plant the largest bulbs in the autumn and smaller ones in the spring. Under no circumstances should you plant all your bulbs in the autumn, because you risk losing all of them.
- Large bulbs should be planted 20cm apart, in rows 30cm apart. Smaller bulbs can be placed close together.
- Two things are especially important, weeding and water. All onions suffer badly from weed competition, so ensure that weeds are kept down. Water is also important. The soil should not be allowed to dry out, or growth will be checked and yield and bulb size will decrease.
- Multiplier onions generally reproduce clonally. For that reason, selection consists of replanting your best material. Do not, for example, replant bulbs that have sprouted, or you will be selecting for poor keeping. Always replant your best bulbs.
Autumn Planting
Multiplier onions 'John Rye'
Autumn planting should be carried out mid-October (a week or two earlier in cold regions, or a week or two later in the warmer areas). The bulbs should be planted slightly deeper than in spring, with 2-3cm of soil over the top of the bulb. If your winters are very severe you might prefer to hill about 7cm of soil over the bulbs, removing this in the spring. Alternatively you could use a straw mulch between 10-20cm thick, again removing it in the spring. The green tops of autumn planted multiplier onions can be used in salads and cooking.
Spring Planting
Plant as soon as the soil is workable. Small bulbs, less than 2cm across, should be planted so they are just covered.
Harvesting
Multiplier onions 'Gloucester Special'
The leaves of multiplier onions will die down in July or August. Stop watering once the tops die down. When about three quarters of the tops have died down you can start harvesting. Any whose leaves have not fallen over should be given another week to ten days to ripen. Any bulbs still green after this time should be eaten as they will not store well.
Do not bend over the tops as this can allow diseases to infect the bulbs. To harvest, lift the bulbs gently by hand or with a fork and leave them on the surface or upturned crate to dry for a week or so. Cover with a cloche or fleece if necessary. Remove excess soil but don’t attempt to clean the bulbs completely, or separate the clusters.
Curing
This is an important process that improves the flavour and hardiness of the bulbs. Move the bulbs to an area that is warm and dry, shaded but well ventilated, and spread them out on wire screens or wooden shelves. Leave them for a month or two, checking every couple of weeks and removing any bulbs that have spoiled. Handle the bulbs as little as possible because they are still quite moist and will bruise easily. Once they have been cured you can separate the clusters and rub off the dry outer scales.
Storage
Bulbs that have been correctly cured will store well over winter, provided they are kept cool, dry and well ventilated. Mesh bags and old tights are ideal containers, but bulbs also do well on shelves or in open boxes provided they are not stacked too deep. Inspect the bulbs every month or so and remove any rotten or sprouting ones.
Returning Bulbs to HSL
Bulbs are easily damaged and may be spoilt if sent by post or carrier. They are also relatively heavy and will be expensive to send. We therefore recommend that you keep bulbs for your own use, or pass some on to friends.
If there are circumstances when you wish to send us bulbs there are some precautions you can take to minimise damage and get them to us in the best condition possible. Bulbs must be dry and clean with a minimum of excess crop debris attached. Any that go mouldy or are badly damaged in transit and will have to be discarded. (It can take a few days to get to us in the post.) Pack them in breathable material (e.g. a paper envelope or cotton bag). If possible deliver in person or ask a friend who might be visiting to bring them. Use ample packing to protect the delicate bulbs from damage before sending them in the post.
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