Knowing when to start leeks from seed to get a big harvest is one of the central goals of vegetable gardening.
When to Start Leeks From Seed to Get a Big Harvest?
Leeks are relatively straightforward crops to germinate and cultivate once seeds have germinated successfully, so timing is of the utmost importance when growing leeks for larger yields. As allium roots tend to spread outward rather than down in seedling-stage soil conditions, it is ideal to choose free-draining soil with good moisture retention that provides adequate drainage as this gives your crop the best start possible.
When To Sow Leeks Depending On Your Climate?
When to start leeks from seed to get a big harvest is also related to the climate of your zones. Leeks can survive temperatures as low as -12degC/10degF and should therefore be grown outdoors during the winter in zones 7b-11b. Cooler regions should still plant leeks during this time but either under glass or indoors for optimal flavor production, while warm regions likely won’t achieve full flavor enhancement come springtime.
These guides apply only to temperate regions in the northern hemisphere for southern hemisphere regions, replace September with March and work backward.
Direct sowing of leeks should always be avoided in favor of sowing indoors in seed trays or plugs and giving the plants time to grow stronger in plugs. This allows all climate zones beyond USDA zones 1-5 (excepting extremes of either extreme winter climate, for which direct sowing may only work once every six hours of sunlight per day will allow germination to happen) to sow indoors right through fall and early winter if day length is adequate for germinating seeds (in general six hours is needed per day for germination to occur).
When to Sow Leeks in Zones 6 & 7:
The colder your climate gets in winter, the later in spring you should sow leeks out. Zone 6-7 has reasonable winters but typically has colder winter temperatures than most are used to, which could rot leaves left outdoors unprotected and unplanted until spring comes around if left uncovered – indoor sowing gives an advantage here by giving plants time to develop until their outdoor sowing in Spring arrives!
When to Sow Leeks Outdoors for Zones 8, 9, 10 & 11:
In zones 8, 9, 10, & 11, it is ideal to plant leeks outdoors between October and November for harvest in spring which will enable continuous summer leek harvest. Sowing should take place in late summer/early autumn to obtain pencil-thick leeks by planting out time.
In zones 8-9 it may be wise to cover leeks over winter to shield them from harsh frosts; in zones 10 & 11, freezing temperatures typically occur only briefly and won’t cause lasting harm to leeks.
When to Sow Leeks, Zones 12 & 13:
Zones 12-13 represent extreme climate conditions ranging from tropical to sub-tropical regions, and leeks do not thrive well under such circumstances; their growth tends to be limited and harvested after only one or two months as baby leeks. When sowing leeks for these extreme environments, consider doing it only every few years to prevent losses of size due to sudden intense heat or rainstorms wilting them before giving it another short growing season or harvesting them as baby leeks after just 1-2 months of growth has taken place.
Which Method Of Planting Leeks Is Best To Sow Indoors, in A Greenhouse, Or Direct?
After knowing when to start leeks from seed to get a big harvest, the next thing is which method of planting leeks is best; indoors, in a greenhouse, or direct.
How To Sow Leeks Indoors?
Indoor sowing of leeks could not be any simpler or more reliable. Simply follow this:
- Prepare seed trays or module trays half-filled with loose, free-draining seed compost.
- Sow two seeds per module or sow thinly into each tray using sieved seed compost.
- Cover with another sieve of sieved seed compost.
- Water well and leave covered for 7-14 days for them to germinate and sprout.
- After germinating your seeds, water regularly as the soil dries to touch.
- Once seedlings reach 1-2inches tall, thin them out so there is only 1 seed per module/inch.
- Continue providing indoor care or greenhouse care until your leeks have grown 5mm thick (the width of a pencil).
How to Sow Leeks in a Greenhouse?
Outdoor greenhouse sowing of leeks for overwinter is possible in zones 6-10; simply be sure that the heater or candles are lit on nights where frosts may occur as extra protection against frostbite.
When to Plant Out Leeks For the Biggest Harvest?
Leeks should only ever be planted out after overwintering indoors if temperatures will not fall below -6degC/21degF, otherwise frost damage will damage young leeks before their roots have time to develop and yield harvest. In zones 5-7 leeks must only ever be transplanted outdoors after having spent their first winter indoors.
Leeks can tolerate temperatures down to -12degC/10degF and therefore, in milder climates (Zones 7-10), can remain planted over winter rather than being plucked out all at once. A cold snap gives leeks their signature buttery and mild onion tones transformed into the sweet taste of roast garlic!
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Final Thoughts!
When to start leeks from seed to get a big harvest is easy once you understand all the dates involved in sowing leeks and have established your hardiness zone, nothing stands between you and producing prizewinning leeks! When harvest time rolls around follow our guide for storing them through winter to extend their enjoyment in your vegetable garden.
Beginning to plant leeks from seed depends heavily upon your location; as a general guideline though, they should always be started when days become shorter; provided there are still six hours of light daily, they should germinate quickly and start growing before winter arrives.