Plant, Grow, and Harvest Leeks
Leeks are a perennial even though they are usually grown as an annual. They need a fairly long growing season requiring a minimum of 80 days for fast growing varieties (such as Columbus and Varna) and 120 to even 150 days for other popular varieties that may be sweeter or milder (such as Titan or Giant Musselburgh)1. Probably the most popular variety is King Richard, which has a 75-80 day growing time.
Leeks like full sun on their growing patch. Soil should be well-mulched and drain well. They do not like acid soil, they prefer a pH of 6 or higher. Leeks like cooler weather for growing, so they do well in temperate and cooler climates. Some varieties will tolerate frost and some will even over-winter if they are mulched. Their ideal temperature is a range from 13-24° C (55-75° F)2.
Leeks can be planted directly in the soil. If so, plant early to take advantage of the cooler spring season. However, remember that a hard frost can still kill them off. For this reason, many people like to start plants indoors. This can be done six to eight weeks before the actual growing season begins. Plant in individual containers to make transplanting easier. Seedlings will look like thin green tubular strands of grass as they initially emerge from the soil.
An easy method to use when planting leeks is called drilling3. After the soil has been turned over and hoed, and the weeds removed, drag the hoe, point down to make a shallow trench (about 5 inches or 13 centimeters). Trenches should be about two feet apart to allow a person to work between rows. Distribute the seeds along the trench. Experience shows that they have a fairly high germination rate, so they can be sown fairly thinly. Cover them with a shallow layer of soil by brushing in part of the ridges (save the rest of the ridge for filling in later blanching) on either side of the row with a hoe or bare hands. Be sure to water the seeds right away with a shower. A hard spray could cause the seeds to bunch together.
As the leeks grow, bank them up so that they can be blanched in a manner similar to blanching celery. This involves slowly covering the stem of the plant as it grows to prevent the sun from turning it green by causing it to go through photosynthesis.
Leeks can be harvested when they get to be 1.5 to 2 inches in diameter (about 5 cm.)4. But many gardeners will harvest them at as little as an inch in diameter. Others believe the taste is best after two or three frosts. To harvest use a garden fork to loosen dirt close to the leeks first. Push the fork in parallel and close to the row. Pull back the handle and force the soil to loosen up around the leeks. Then pull them up by the leaves. The leaves can be cut into a "V" shape (outside shorter) to help slow transpiration (water loss) that can make the leeks limp.5
It is best to harvest just before use. However, leeks can be stored for several weeks in a root cellar standing upright in a box with some sand in the bottom. They can also be placed in a refrigerator for two to three weeks. So if the harvest is big, have a plan for their immediate use or preservation. Of course, the best leek is fresh, but they can be frozen in prepared soups, canned in soups, pickled, or even dehydrated.
Find out how to grow a cornucopia of vegetables in your garden.
- See the University of Wisconsin Website for more info on different varieties.
- New South Wales Govt. Website
- Gardening Data on Drilling Leeks
- USA Gardener on when to Harvest Leeks
- Some good pointers on harvesting leeks from DoItYourself.com.