Instructions for Growing Leeks As An Early and Late Crop In The Vegetable Garden
You can grow leeks in one of two ways – either as an early spring crop
similar to onions or as a late season crop by direct sowing into the
For the early crop, sow seed in pots or flats as thinly as possible.
Do this approximately six to eight weeks before you want to transplant
them outdoors. Late April is a good time for outdoor planting in zone 4
so the seeding date is the beginning of March. Sow seed one quarter
inch deep, cover the seed and gently firm the soil.
Keep the soil temperature at 65-70F and you should see a germination
rate of 75% or so within two to three weeks.
This seed does not germinate as quickly as onions nor does it germinate
as completely as onions do. If you have the ability to cool the seeds
down at night, you'll find they germinate a little bit better. So day
germination temperatures around 70F and night temperatures around 60F
will give you optimum germination.
There are two schools of thought about the tops. The first says to trim
the tops off – cut the leek halfway back – when it gets to four to five
inches tall. The thinking is that this bulks up the root and makes
transplanting better. This is the time-honoured method.
A second school says not to cut back the tops as this retards the
performance in the garden and this has been suggested by at least one
Whichever you pick (I never cut them back after I read the article)
after they germinate, you want to grow them at 50F to keep them short
and blocky. Higher temperatures will indeed cause them to get too tall
and perform badly in the garden.
Feed every week with a balanced fertilizer to keep them growing
As soon as you can get onto the garden (late April) transplant them
outside. The way to do this is to dig a six inch deep furrow and plant
the leeks at the bottom of this furrow or trench. Over the course of
the growing season, the trench is gradually filled in when you
cultivate near the leek. This will blanche the leek. Seedlings should
be planted approximately four to six inches apart. Thinnned to six
inches when the crop gets really growing.
Note that leeks like rich, fertile soil so adding compost is necessary
if you want a great crop. They also do not like being water starved so
plan on feeding and watering this crop for best results.
If you want a late crop, dig the furrow and plant the seed directly
into the furrow Plant one seed to the inch and thin to the strongest
seedling every six inches. This can be done from the end of April to
June to get a crop to harvest in the fall. Remember that you have to
keep the seed damp if you want germination.
Leeks are usually dug in October before a really hard frost softens
them. They are usually used fresh although storage in frost free
conditions will keep them for a long time. I'm told if you keep the
frost away from them and bank them up with straw that they'll start
growing again the following April which will make them very early to
harvest and eat. Given our zone 4 climate, I've never done this. I'd
have to move the leeks about 500 miles straight south to stop frost.