John's advice after 25 years growing at Ashbrook allotments
Leeks
Leeks are a very useful winter crop, they can withstand harsh winters and grow well at Ashbrook. They are also a very useful catch crop that can be transplanted in July when early potatoes, peas or broad beans have been cleared. Leeks are an allium so avoid planting them on ground from which shallots or onions have been cleared, also avoid planting in ground suspected of being infected with onion white rot.
Seed is sown in April in seed trays, pots or in a seed bed, germination takes about three weeks. My own leek seed is sown in ½” deep drills in a seed bed on my allotment. The plants are grown on until they are about the size of a pencil and transplanted to their final positions in July. If the ground is dry the plants are well watered the day before being lifted with a fork. I trim the leaves and roots by half, this is to encourage fresh root growth and so the remaining leaf stands upright, if untrimmed some leaves often wilt and can be drawn underground by worms resulting in the young plant being pulled over.
Leeks do best in fertile soil so a dressing of general fertiliser such as fish, blood and bone raked in before planting will help. Form planting holes about 15cm (6”) deep using a dibber and transplant into double rows allowing about 30cm (12”) each way, and water each plant in. If the ground is dry keep the plants watered for a few days until they establish and start growing strongly.
Leek moth is a major problem in many parts of the country. It arrived in the UK about 2003 and arrived at Ashbrook in July 2012 and is now with us for keeps, that autumn many of us had our plants severely damaged. The adults emerge during April when the first generation of eggs are laid, it is the next generation of eggs laid about July that is the greatest problem with the damage caused by the larvae not showing until August and September. Leaves appear slug eaten and the larvae found within the shank cause further damage often leading to botrytis. The larvae overwinter as pupae either in the soil or within old crops and foliage and hatch out the following spring. Any crops or foliage found with these pests should not be put on compost heap or left lying around. You can take a chance that the moths avoid your crops however the best solution is to cover your plants with insect mesh, 1.6mm mesh is adequate, supported on either a timber frame or polythene tubing from planting out until about mid October by which time any surviving adults and their pupae will be hibernating. Since 2012 my leek seed bed has been covered when the seed is sown and after planting my leek plants have been covered with environmesh and for the past five years I have had no problem.
Another similar pest which will also attack leeks is allium leaf minor which although on allotments a few miles away does not seem to have arrived at Asbrook yet, when this one arrives it will also go for our other alliums e.g. onions, shallots and garlic.
The two pests are often confused and damage to leeks by either is similar. However being a moth leek moth larvae is a small caterpillar, allium leaf miner is a fly hence the larvae is a maggot.
Leeks are also prone to leek rust, this often appears during wet and humid weather in the autumn and spring. Although this can disfigure the foliage the edible part is generally unaffected. Rust infected material is best disposed of away from the site.
Suggested varieties:-
Seed is sown in April in seed trays, pots or in a seed bed, germination takes about three weeks. My own leek seed is sown in ½” deep drills in a seed bed on my allotment. The plants are grown on until they are about the size of a pencil and transplanted to their final positions in July. If the ground is dry the plants are well watered the day before being lifted with a fork. I trim the leaves and roots by half, this is to encourage fresh root growth and so the remaining leaf stands upright, if untrimmed some leaves often wilt and can be drawn underground by worms resulting in the young plant being pulled over.
Leeks do best in fertile soil so a dressing of general fertiliser such as fish, blood and bone raked in before planting will help. Form planting holes about 15cm (6”) deep using a dibber and transplant into double rows allowing about 30cm (12”) each way, and water each plant in. If the ground is dry keep the plants watered for a few days until they establish and start growing strongly.
Leek moth is a major problem in many parts of the country. It arrived in the UK about 2003 and arrived at Ashbrook in July 2012 and is now with us for keeps, that autumn many of us had our plants severely damaged. The adults emerge during April when the first generation of eggs are laid, it is the next generation of eggs laid about July that is the greatest problem with the damage caused by the larvae not showing until August and September. Leaves appear slug eaten and the larvae found within the shank cause further damage often leading to botrytis. The larvae overwinter as pupae either in the soil or within old crops and foliage and hatch out the following spring. Any crops or foliage found with these pests should not be put on compost heap or left lying around. You can take a chance that the moths avoid your crops however the best solution is to cover your plants with insect mesh, 1.6mm mesh is adequate, supported on either a timber frame or polythene tubing from planting out until about mid October by which time any surviving adults and their pupae will be hibernating. Since 2012 my leek seed bed has been covered when the seed is sown and after planting my leek plants have been covered with environmesh and for the past five years I have had no problem.
Another similar pest which will also attack leeks is allium leaf minor which although on allotments a few miles away does not seem to have arrived at Asbrook yet, when this one arrives it will also go for our other alliums e.g. onions, shallots and garlic.
The two pests are often confused and damage to leeks by either is similar. However being a moth leek moth larvae is a small caterpillar, allium leaf miner is a fly hence the larvae is a maggot.
Leeks are also prone to leek rust, this often appears during wet and humid weather in the autumn and spring. Although this can disfigure the foliage the edible part is generally unaffected. Rust infected material is best disposed of away from the site.
Suggested varieties:-
- Musselburgh – an old and reliable Scottish variety.
- Toledo – This one has produced good leeks for me over many years and gives long shanks for use between November and March.
- Below Zero – An F1 variety reputed to be rust resistant, I grew it for the first time in 2017 and although mine had some rust for a while they did recover and produced very good leeks from November until the end of March.