Leeks are amongst the easiest vegetable garden crops to grow, yet many people are disenchanted with them not growing to harvest size with the predominantly white base, as shop-bought ones have.
The best way to overcome this is the humble toilet roll. When planting seedlings, slip an empty toilet roll over the seedling and grow on as usual. The toilet roll has a 2-fold benefit - it protects the young seedlings from wind damage, which can be problematic when they're young, and also stops the light getting to the base of the plant, which results in white bases like the shop-bought ones!
Perfect leeks every time!
Cheers,
John