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Jaune de Poitou Leek

Leeks - Allium ampeloprasum var. porrum
Family - Amaryllidaceae

Leeks are an easily grown cool season member of the onion family that produces quite well in Las Cruces soils and climate. Even though they are classed as a cool season crop, they can be grown here year round with proper timing and propagation. You can harvest this non-bulbing allium at all stages during its growing cycle have freshly harvested small and large leeks from the same planting.


There are many ways to grow leeks here successfully, but the planting schedule below is the easiest and most dependable way to manage timing and deliver a year-round supply of fresh leeks from garden to table.

You can use the same schedule if starting seeds outdoors with some exceptions. Your spring seedlings will mature more slowly, because of cold nighttime temperatures, but the plants will grow quickly once it warms up. Using row covers will speed up early growth considerably. Starting the fall planting outdoors requires that you provide some shade for the seedlings or they will stall out in summer heat (and may not recover). A double layer of row cover will provide enough shade (about 30%) to keep seedlings from stalling.

Seedling Tips - Starting seeds in 4" pots instead of six packs provides more root room and yields faster growth. You can grow leeks in clusters of 2, 3 or 4 together to reduce the number of seedlings you transplant.

Below The Surface

Leeks have a shallow, dense and fibrous root system, so its important to transplant them deeply to avoid drought and hot soils - it also yields you longer more tender shanks for eating. Leeks grow fastest with a constant and even supply of water. This spring I planted leeks into an olla watered bed and into one that I have hand watered. Leeks in the olla watered bed grew at least three times faster that the hand watered ones. (all other conditions were as equal as possible) Its a little extra work, but a self regulating subterranean watering system really pays off with faster growth in leeks.

Transplanting Tip -Trim off 1/3 of the root growth and 1/3 of the top when transplanting to stimulate root growth and reduce transplanting shock. Set transplants up to the first leaf junction but no deeper. Set single leek transplants on a 3-4" grid spacing - increase the spacing for clusters of 2, 3 or 4 leeks.

Leeks grow best in rich soil with abundant organic material (how often have you hear that?) If you are growing organic, amend the soil with finished compost, rabbit and chicken manure two to three months before planting - giving plenty of time for aging. If that's not possible add finished compost, a phosphorous source such as soft rock phosphate, bone meal, or composted bio-solids and a nitrogen source such as cottonseed meal a couple of weeks before planting. Leeks require equal amounts of nitrogen and phosphorous fertilization. Our soils generally have adequate amounts of available potassium (unless your soil test shows otherwise), but needs additional phosphorous and nitrogen for rapid leek growth. If you are using chemical fertilizers apply a 10-10-10 rated fertilizer before planting and side dress when the leeks are about 1/2" in diameter.

Mulching transplants to reduce soil temperatures is really important in spring and through summer. In winter use a very thin mulch to increase soil temperatures.

Irrigation Tip - - Leeks grow fastest with a constant supply of soil moisture. If you are growing the second year for seed, during blossom set is a critical times to avoid water stress.

Above The Surface

The only time leeks are adversely effected by air temperatures is in the seedling stage. Once beyond about 1/4" in diameter they take all the heat Las Cruces can deliver and seem unfazed (if adequately watered). Fortunately leeks are seldom effected by diseases or insect pests and can be grown in permanent beds with little risk of culturing diseases.

Its easy to grow your own leek seed, requiring only patience and occasional thinning. Leeks are biennials and will put up bloom stalks in June of their second year. The flower heads take forever to bring in mature seed, so plan on waiting until September before harvesting seed for next year. Seeds will remain viable for 2-3 years if kept dry and stored in a cool place. Before the seed heads are ready to harvest you will see new leeks growing from the base. The old plant will eventually die out leaving space for the new basal sprouts to form into mature leeks. Sow a few of the new seeds into the old bed and you have a permanent year round producing leek bed with very little work.

Growing your own fresh and delicious leeks can be done easily and dependably with basic knowledge, a fertile soil and a little attention.

Further Reading

Why Not Leeks?

To Vichyssoise and Beyond

Leeks - Oregon State University Commercial Production Guide

Good Gardening and Good Eating

Darrol Shillingburg
Doña Ana Extension Master Gardener
July 2011


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