Pollination

Blanching

Leeks are often blanched to get a longer area of white stem, as this is considered superior to the green part. Blanching is usually done with soil, either by earthing up the stems to just below the first leaf, or filling up the trench they are growing in. Some gardeners wrap corrugated cardboard collars around the plants before blanching, to prevent soil getting lodged between the leaves (no one likes gritty Leeks). You can also blanch the stems with a deep mulch, which has the advantage of not being gritty.

Perennial

Leeks can be treated like perennials, as they propagate themselves vegetatively by means of offsets. They may also self-sow.