Agriculture Reference
In-Depth Information
These leeks were overwintered in sand and have been laid out in preparation for planting.
WHAT YOU'LL NEED
• 10 to 15 healthy plants
• overwintering strategy
• isolation strategy, if multiple varieties are being grown for seed
POLLINATION NOTES
Like onions, leeks are outcrossers. See onions for information on isolation and
pollinating insects. Cultivated leeks do not cross with chives, onions, or bunching onions; they do,
however, cross with many wild varieties of
Allium ampeloprasum
and with pearl onions. Summer vari-
eties often do not flower; when they do, flowers are sterile.
PROPAGATION
Leeks are grown for seed as biennials. Grow the first year as you would for eating.
Plants may flower in the first year; do not save seed from these plants. Contrary to what suits the
onion, cool, wet weather makes for ideal growing conditions for the leek. Depending on the variety,
leeks are hardy to zone 3 or 4 and can be overwintered outdoors down to these zones, even when a few
leaves suffer some frostbite. Overwintering indoors may be safer, however, depending on your local
conditions.
Summer leek varieties are usually propagated vegetatively. They are hardy only to zone 5 at best
and should be overwintered indoors below zone 5 in a relatively dry cellar or in a heated greenhouse.
In general, the darker and tougher the leaves, the more winter hardy the variety is. Blue or violet hues
in ripe leaves also indicate winter hardiness. Plant out leeks in the spring as soon as the ground can be
worked. Plants send up a tall flower stalk in the spring. A long-tipped husk develops at the end of the
stalk by midsummer, which then falls off, exposing the typical allium flower head. Leeks bloom later
than onions and have stronger stalks, though they still need support.
HARVEST
Seeds ripen relatively late. Remove seedheads of slower-ripening plants and hang to dry in
a cloth bag indoors with good air circulation. If no plants ripen seeds by the end of the growing season,
cut entire stalks, bind into sheaves, and dry indoors with a tarp underneath the sheaves.
Leek seeds sit in their husks more firmly than onion seeds in theirs; nonetheless, the process for
threshing is the same as for onions.
