The Vegetable Garden

How To Grow Onion And Shallot From Seed

How To Grow Onion And Shallot From Seed
Onions are one of the most versatile vegetables and are quite easy to grow. Many people grow Globe Onions from sets - immature bulbs - although seed is a good and straightforward starting point, as it is for shallots. These too are also often grown from sets.


Sow indoors January to February for largest bulbs. Sow thinly 0.5cm/quarter-inch deep, in trays of seed compost. Keep at a temperature of approximately 15°C/60°F. Or Sow outdoors March to April, sow thinly 1.5cm/half-inch deep. Allow 30cm/12in between rows and when large enough, thin out to 20cm/8in apart. 

Harden off April-May. Plant out 20cm/8in apart, in rows 30cm/12in apart. Keep well watered and weed free. Harvest August-September.


Water if the weather is dry and feed occasionally with an onion fertiliser. A light feed of sulphate of potash in June or July will help ripen the bulbs. Mulching the soil will help conserve soil moisture and keep down weeds using a narrow hoe or onion hoe, being careful not to damage the developing bulbs.


Harvest onions when the foliage turns yellow and starts to topple over. Leave for two to three weeks and then carefully lift with a garden fork. Those for storage must be firm, disease free and then dried for two to three weeks, either laid out in the sun or in a shed if the weather is wet. The foliage of shallots will start to turn yellow in July. Lift the bulb clusters, separate them and allow to dry.

Top Tips 

For giant bulbs that will be the envy of neighbours and win prizes at shows, try varieties like Onion Exhibition or Kelsae and be sure to sow early.

Stop watering and feeding once the onions have swollen and remove any mulch or soil with your hands, to expose the bulb to the sun.

Remove any flower spikes as soon as they are seen to keep bulbs in good condition.

Be careful harvesting and handling onions as they bruise easily and this can significantly reduce their storage time.

Onions with 'Bull necks', large thick necks, should be used first as they won't store as long as others

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