Leeks prefer a sunny, well cultivated, sheltered site with rich well-drained soil. As they will sit in the soil for a long time, they are ideal crop for the allotment, although many have fantastic foliage that makes them an ideal vegetable to grow in flower borders or an ornamental potager.
Leek F1 Oarsman has been awarded the RHS Award of Garden Merit.
Preparing the soil:
If possible, prepare the soil for planting in the winter. Dig the site well, removing weeds and working in plenty of well-rotted manure to improve its ability to retain water. Leeks can be planted in heavy soil, but improve the drainage by mixing in some horticultural sand. This is a hungry crop – spread a general balanced fertiliser over the soil a week or so before sowing and rake in. A rate of 60g per square metre is ideal.
If you live where the autumns are long and cool and frost is rare, you can plant two crops. Sow the first crop 12 to 14 weeks before the last frost in spring.
In mid-July, sow the second crop indoors. If your area could experience frost during the winter, plant a frost-tolerant variety for your second sowing
Sow seeds indoors 12 to 14 weeks before the last frost date
Seeds can also be sown direct later but will give smaller plants
Sow the seeds thinly and evenly 6mm (1/4in) deep in moistened potting mix and cover them lightly with vermiculite or sand. Keep the soil temperature at about 70°F until the seeds germinate. Move the seedlings under grow lights or into a very bright window.
Thinning the seedlings will encourage more rapid growth, but it isn't necessary if you keep them well fertilized. When the grass-like seedlings get to be 15cm (6in) long, cut them back by 4cm (1½ to 2in) You can use the part you cut off as you would chives.
Harden off the plants before transplanting into the garden starting in late April or early May (the plants will tolerate light frost). You can also transplant later or sow seed directly outdoors for smaller plants.
Transplanting: When the seedlings are about the diameter of a pencil, they are ready to transplant outside. Planting deeply helps to blanch the stems. Use a dibber (or a rake handle - great for making perfect holes). and make holes 15cm (6in) deep and 22cm (9in) apart. Make the rows 38cm (15in) apart. Mark the row clearly so that, when weeding later you don’t remove plants by mistake.
Drop the leek seedlings into the holes leaving just the tips of the leaves showing. Do not fill in the holes or try to cover the roots with soil or even firm them in. Just fill each hole with water from the watering can and this will wash some soil over the roots and be just enough to tighten the little plants in. Over time the holes will fill up gradually.
On the allotment seeds are best sown in rows, 35 to 40cm apart. Mark a straight line and use the corner of a rake to make a shallow groove in the soil, about 1cm deep. Sow seed thinly along the trench, cover with soil, water and label. When seedlings have three leaves each, about four to five weeks later, thin to leave plants every 15cm – the seedlings you remove could be used to plug gaps elsewhere.
Keep the leek bed moist in dry weather and hoe regularly to keep the weeds down. Except for exhibition plants there is no need to feed the leek plants. But if you want to be sure of a good crop you can feed with weak liquid manure and hoe in a small dressing of nitrate of soda.
After the holes the leeks were planted in have filled up, push some soil up to the stems with the hoe. This will make sure you will have a good length of white (blanched) stem. Do this earthing up gradually over a period of three weeks because if done too much to soon, the leek plants may rot. Mulch will help to retain moisture over summer.
Avoid following onions, shallots, garlic and chives.
Beet, carrot, celery, garlic, onion, parsley and tomato.