• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

My, what big leeks you have!

A gardeners guide: the secrets of growing leeks for the trial at RHS Garden Wisley from sowing to assessment

leek on trialThis year we have been growing leeks for assessment on the Trials Field. There are 27 different varieties being compared and two extra varieties grown as exhibition leeks for the public to see.
In April we forked over the seed bed to relieve compaction, then trod and raked it level. We then sowed the leeks in two half rows of 3.5m (11ft) in the bed at a 30cm (1ft) spacing. Finally we covered them with crop protection netting to prevent leek moth, thrips and allium leaf miner from attacking the plants.
We similarly prepared the ground for the final position for the leeks, although we rotavated the area rather than forking this time. In May I applied fertiliser to the area at the recommended rates of nitrogen, potassium and phosphorus and also sprayed the bed with glyphosate, prior to planting, to check the weed growth.
Planting out
Webed of leeks planted the two varieties of exhibition leeks, ‘Pendle Improved’ and ‘Welsh Seedling’, in mid May; these had been grown first in a nursery. Next we wrapped the stems with  23cm (9 inch) collars of builders’ damp-proof course (DPC), to blanch them, and tied them to canes to ensure they grow straight. We have found that DPC is very useful material for blanching as it provide both support and removes light from the leek stems. We again covered them in crop protection netting using water pipes as support. As they grew we changed the DPC for longer pieces, increasing them to 30cm (1ft) and then 45cm (18in).
Once they were big enough, we transplanted the rest of the leeks from the seed bed to their final position in June (roughly 10 weeks after sowing). Leeks were ideally around 20cm (8in) high and of pencil thickness to be ready.
Trimming and blanching
leek crop protection75 suitable leeks of each variety were dug up and we trimmed the roots to ensure they fitted in the 15cm (6in) deep holes we created by using dibbers. The leaves were also trimmed back to reduce water loss. We dropped the leeks in the holes to blanch the stems as they grow. They were positioned 15cm (6in) apart and in 3 half rows of 3.6m (11ft) long and each hole was filled with water from a watering can to settle them in, so no need to firm in or back fill the holes with soil. As before, we covered all the entries in crop protection netting after planting to prevent leek moth, thrips and allium leaf miner from attacking the plants.
Since then we have regularly watered them, especially during the hot summer months (every day for a while with the overhead sprinkler) and hand weeded them as they grow. At the end of August I gave them a granular nitrogen feed. We recently started spraying for rust as some were showing signs of the disease.
The first forum meeting will be at the beginning of October 2015 when they will be assessed for their size, vigour and flavour for AGM worthiness. A further two more assessments will take place and some of each variety will be left in the ground until the spring to see how they overwinter. Once finished we will harvest them for the restaurant to use in their recipes.

Come down to the Wisley Trials Field to see them all soon.

Grow your own leeks

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