Leeks, elephant (or great-headed) garlic, and kurrat are closely
related. Three types of leeks can be recognized by their morphological
Leeks are widely adapted, reportedly grown from Cuba to Norway. They
are grown most commonly from seed, but may be propagated from topsets
in the flower umbel, from bulbils in the basal plate, or from bulbs
formed after the plant flowers. Varieties have been developed for
resistance to cold and a wide range of winter hardiness is available.
Winter hardiness is strongly correlated to a short pseudostem.
- The European leek which develops a short, thick pseudostem.
- The Turkish leek which develops a relatively long and thin pseudostem.
- The Kurrat, which does not produce a pseudostem and is grown around
the Mediterranean and in the middle east for its leaves. These leaves
can be harvested several times a year.
VARIETIES (approximately 80-120 days).
Main fall varieties (August through October): American Flag, Jolant, Kilima, King Richard, Primor.
Late fall - winter (October through December): Derrrick, Electra, Goldina, Goliath, Kilima, Tivi, Wintereuzen.
Overwinter (spring harvest): Carina. For trial: Conqueror (moderate bulbing), Eskimo, Siberia.
SEED AND SEED TREATMENT
Leek seed numbers approximately 176,000 per pound, but leeks are not
commonly direct seeded. Use treated, high quality seed for transplant production. Leek seed, like
other alliums has very limited useful viability (less than 2 years) unless stored under ideal conditions.
TRANSPLANT PRODUCTION AND PLANTING
Direct field seeding is possible but not recommended due to the lack of
registered herbicides and length of time needed to harvest from direct-seeded plantings (8-12 months or
For transplants, plant into containers as indicated below, or 1/2 oz of
seed per sq. yard in early spring in greenhouse or field beds in March. Grow for 8 to 10 weeks before
Harden off plants for a week or two and transplant at 10-12 weeks, or
when pencil thick, into rows that are 18 to 24 inches apart, with plants at 4 to 6-inch spacing within
the row. Use spacings that would allow soil to be moved from between the rows toward the
plants in order to adequately blanch the stems. Leek plants are sometimes planted into 3 to 4
inches deep holes made by a dibble or dibble board. This produces long white stems that are
desirable in the market.
Approximate seeding, transplanting and expected harvest dates are:
Transplant Sow Seed Field
Containers for Transplant Spacing
Crop or Seed Bed Transplants to the Field Harvest inches
Early in greenhouse, mid-Dec. to mid-March/ July/Aug. 18 x 4
modular trays or mid-Jan. early April
Summer warm frames mid-Jan. to April late July/ 18 x 4
late Feb. late Aug.
- early cold frames March early-mid late Aug/ 24x 6
June late Oct.
- late cold frames late March mid-late Nov.-Dec. 24 x 6
early Apr. June
- early outdoors 1st half 1st half Jan.-Feb. 23 x 6
- late outdoors 2nd half 2nd half March-May 24 x 6
April April July NOTE: RISK OF BOLTING
Leeks grow best in a cool to moderate climate. The Willamette Valley
and Oregon Coast are ideal. They can be grown here year round.
A well-aerated soil with both good drainage and good moisture retention capacity with a pH of
6.5 to 7 is best. Deep plowing is recommended so that a longer shaft can be developed.
Even on fertile soil apply, when available, 25-35 tons of manure per
acre during the fall or early winter.
The following recommendations are general. It is advisable to use a
soil test for each field to be planted.
Nitrogen: 150-200 (N) lb/acre. Spread over several applications. Use higher
rates on sandy soil and with later varieties.
For Nitrogen liquid fertilizer formulations having weed control properties in leeks and other alliums, see
the file Nitrogen Fertilizer Solutions Providing
Ancillary Weed Control in Alliums
Phosphorus: 150-250 (P2O5) lb/acre.
Potassium: 100-150 (K2O) lb/acre.
Sulfur: 30-50 (S) lb/acre.
Boron: 1-4 (B) lb/acre.
Irrigate uniformly to maintain vigorous, uniform growth and tender
stalks. A total of 12-15
inches of water may be required depending on planting date, seasonal variation
Soil type does not affect the amount of total water needed, but does
dictate frequency of water
application. Lighter soils need more frequent water applications, but less
water applied per
HARVESTING AND HANDLING
Leek yields are approximately 370 cwt/acre. Leeks do not bulb or go
dormant in the fall but
continue to grow slowly. The time of harvest is, therefore, very flexible,
depending on the time of
planting, market conditions, and variety of leek planted. Small leeks can be
sold starting in early
August, and varieties that have frost tolerance may be harvested throughout
the fall and winter
Machine harvest of leeks is now possible, but most leeks are lifted
or dug by machine and then harvested, cleaned, and packed by hand.
Single or multiple-row harvesters can be custom built by
Krier Engineering, 4774 Morrow Rd., Modesto, CA. Contact Mr. Alex Krier, 800-344-3218, for more information.
STORAGE (Quoted or modified from USDA Ag. Handbook 66 and other sources)
Store leeks at 32 F and 95 to 100 % relative humidity. Leeks, if
properly handled, should keep
satisfactorily for 2 to 3 months at 32 F. Storage conditions are similar to
those for celery and
green onions. Leeks should be cooled promptly after harvest to near 32 F by
crushed ice, or vacuum cooling; and they should be kept at that temperature
with high relative
humidity throughout storage. Yellowing and decay develop rapidly at warmer
temperatures. High relative humidity is essential to prevent wilting.
Moderate wilting will be
noted when leeks lose about 15 % of their weight after harvest. The use of
crate liners and of crushed ice can aid in preventing moisture loss. In one
series of tests, freshly
harvested and trimmed leeks prepackaged in sealed, non perforated polyethylene
bags held up
well for 10 weeks at 32 F under crushed ice. No off-odors, off-flavors, or
tissue injury from
carbon dioxide build-up or oxygen depletion were found in leeks in the sealed
Good refrigeration will retard the elongation and curvature that develop
in leeks at 50 F or 70 F.
Respiration or heat evolution of leeks is about eight times faster at 70 F
than at 32 F.
Storage for 4 to 5 months at 32 F is possible by using a controlled
atmosphere (CA), although
there will be some loss in quality. The best CA contains from 1 to 3 % oxygen
and from 5 to 10
% carbon dioxide. This CA retards yellowing and decay. Atmospheres
containing 15 to 20 %
carbon dioxide cause tissue injury.
Cultivar, preharvest and postharvest conditions, degree of trimming, and
method of packing will all influence the storage life of leeks.
Leeks are commonly trimmed to 12-inch length, bunched in 3`s depending
on diameter, and often
placed in polyethylene film bags. They are usually packaged in 10-lb cartons
or wirebound crates,
holding 10 film bags, each 1 lb. Other crates may be packaged with 18-24
bunches with a net weight up to 30 lb.
DISEASE CONTROL FOR LEEKS
THE FUNGICIDES LISTED BELOW ARE FOR INFORMATION ONLY AND ARE REVISED ONLY
ANNUALLY. BECAUSE OF CONSTANTLY CHANGING LABELS, LAWS, AND
REGULATIONS, OREGON STATE UNIVERSITY CAN ASSUME NO LIABILITY FOR
THE CONSEQUENCES OF USE OF CHEMICALS SUGGESTED HERE. IN ALL CASES,
READ AND FOLLOW THE DIRECTIONS AND PRECAUTIONARY STATEMENTS ON
THE SPECIFIC PESTICIDE PRODUCT LABEL.
USE PESTICIDES SAFELY!
Wear protective clothing and safety devices as recommended on the label.
Bathe or shower after
Read the pesticide label--even if you've used the pesticide before. Follow
closely the instructions
on the label (and any other directions you have).
Be cautious when you apply pesticides. Know your legal responsibility as a
You may be liable for injury or damage resulting from pesticide use.
Note that Oregon law requires the reporting of agricultural pesticide use to the Oregon Dept. of Agriculture through
its on-line PURS program.
The Pacific Northwest Disease Control Handbook has no control entries for
this crop. Fungicides registered on leeks,
but not evaluated by University personnel in the Pacific Northwest, include:
Bravo, COC, Ridomil, and Telone.
Consult labels for rates, restrictions, and diseases controlled.
Most diseases that attack onions also may affect leeks. Proper
rotations, field selection,
sanitation, spacings, fertilizer and irrigation practices can reduce the risk
of many diseases. Fields
can be tested for presence of harmful nematodes. Using seed from reputable
sources reduces risk
from "seedborne" diseases.
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