Home > Useful Information > Care & Cultivation > 

Need help?
Call 0333 777 3936


Care & Cultivation

Care and Cultivation of Onion and Leek Plants

What to do First

Sending plants by post may cause them a little stress, so unpack them immediately. If the roots are at all dry, stand them for a few minutes in about 2.5cm (1in) of water until the compost is fully moist again. You may notice a slight yellowing of the foliage, but this is quite natural after they have been in a dark package and is nothing to be worried about; they will soon recover.

These plants are fully hardy and should be planted out immediately, as long as the ground is workable. If, for any reason, you have to delay planting for a day or two, temporarily plant them out in a tray of moist general purpose compost. Then place them in a spot outdoors where they are in a good light but out of direct sun.

Planting Out

Choose an open, sunny site with well-drained soil, and if possible, use ground that has not grown onions, leeks or related plants for several years. Land that has been prepared with plenty of rotted manure or compost, dug in during the autumn or winter is ideal. Onions are most demanding of fertility but even leeks will give disappointing results if the soil is poor. Lime if your soil is acid, and before planting, rake in a dressing of a general fertiliser, such as Growmore.

Using a garden line to ensure the rows are straight, plant out the onion seedlings approximately 10cm (4in) apart, in rows 25cm (10in) apart. Dig a sufficiently large hole with a trowel and set the base of the bulb about 13-20mm (½-¾in) deep, firming in afterwards. Water in if the soil is not already moist.

Leeks need to be 15cm (6in) apart, in rows 30cm (1ft) apart. At each planting site, make a 15cm (6in) deep hole with a dibber and drop a seedling in. Then fill the hole with water to settle some soil around the roots. Don't fill the hole with soil.


The very sparse foliage produced by members of the onion family does little to mother the growth of weeds, which compete for light, nutrients and water. Because of this, it is particularly important to regularly handweed or hoe around the plants and between the rows.

Water when the weather is dry, but stop watering onions when the bulbs have swollen.

As leek plants develop, draw up soil around the stems in stages so as to increase the length of white stem. When doing this, be sure to avoid and soil falling between the leaves and complete this earthing up by October.