Growing Leeks

Latest Update 8th July 2016.

  • The leaves make a fine addition to soups and casseroles etc, and I like nicely blanched leek stems steamed with a little seasoning as an accompaniment to fish dishes.
  • Leeks are best cooked as soon as they are harvested.  They are slow growing and can be harvested as required over a few weeks.
  • They are an excellent source of vitamins, minerals and dietary fibre.
  • Variety:                                                    King Richard.
  • Family group:                                           Allioideae.
  • Crop rotation group:                                  Light Feeders.
  • Garden bed type:                                      Garden Ecobed.
  • Recommended soil pH:                              6.0 - 8.0.
  • Minimum sun per day:                              4 hours.
  • Plant spacings (centres x rows)                 150 x 150mm.
  • Weeks to harvest:                                     25 - 18 weeks.
  • Good companions:                                   Carrot.
  • Climate:                                                   Warm temperate
  • Geography:                                              Southern hemisphere.
  • This food is very low in saturated fat and cholesterol.  
  • It is also a good source of dietary fiber, vitamin B6, folate, iron and magnesium, and a very good source of vitamin A, vitamin C, vitamin K and manganese. 
  • More from nutrition
Growing Conditions: 
  • They grow best in full sun.
  • They need well structured rich organic soil.
  • The soil must be kept moist at all times. 
Soil Preparation.
  • Clear a space for leeks and add a 60mm layer of home made compost, then cover with 50mm of fresh straw mulch. 
  • Leave the bed for 4 weeks to build up microbial activity before planting the first crop.
Growing Instructions.
  • Sow leek seeds in February on the surface of an organic seed growing mix in a punnet, and lightly cover with sieved growing mix. 
  • Soak the punnet for an hour in a tray containing 10mm of water (preferably rainwater).  The water will wick up into the soil without flooding it. 
  • Sink the punnet to its rim in a Propagator.  This will keep the soil moist until the seedlings are ready to transplant.  Protect them against frost. 
  • When the seedlings are about 200mm tall, remove their punnet from the propagator and sink it into the prepared soil up to its rim.  Leave it there for a few days to harden off before separating and planting the seedlings in the prepared bed. 
  • Use string lines to mark out rows 150 mm apart, and plant the seedlings at 150 mm intervals along each row.
  • Make a hole for each seedling about 100 mm deep with a dibber and plant the seedling so that about 1/2 of the stem is visible above the surface.  Backfill with soil and water in well.
  • Apply a foliar spray of aerated compost tea every 4 weeks at the same time as all the other edible plants.
  • Mulch around the leeks in spring as the weather warms.
Repeat Sowing.
  • Sow leeks in August in the propagator ready for planting about 6 weeks later.
  • Protect the seedlings against extremes of weather.
  • When the seedlings are about 200mm tall, remove their punnet from the propagator and sink it into the prepared soil up to its rim.  Leave it there for a few days to harden off before planting the seedlings in the bed. Water them in well.
  • Leeks should not be grown more than once in the same patch of ground each season.  Follow one of the other light feeder group instead.
Harvest and Storage
  • Harvest the leeks in August and February. 
  • They ready as soon as they are big enough to use.
  • Cut them off at ground level and leave the roots to decompose in the soil.
  • They don't store well so harvest them as needed in the kitchen.  
Organic Pest Control.
  • Slugs and snails.
    • Leeks should be protected against slugs and snails using self adhesive copper tape bonded around the base of your Ecobeds.
    • If these molluscs get into your Ecobed as eggs laid in your compost, kill them with organically approved iron based snail pellets as soon as you discover them.  You should only need to use a small number of pellets.
  • Aphids (blackfly).
    • Aerated compost tea improves the plants resistance to blackfly damage.
    • Adult blackfly usually mate in autumn and the eggs are laid on the leaves of leeks and other alliums.  They overwinter in situ and hatch in spring, so you need to look for them as the weather starts to warm.
    • Control any infestations by spraying your crop thoroughly with organic horticultural oil (Eco-oil in Australia).  This smothers the insect, but as you need direct contact make sure you spray them thoroughly.
    • Spray again in a few days to make sure none escape, as they multiply rapidly by an amazing process (see section on "reproduction" in link).
  • General:
    • Regular applications of aerated compost tea boost the natural defences of leeks by colonising the leaf surfaces with beneficial microbes.  They defend the plant against airborne pests and diseases. 
    • Similarly, proper soil preparation including regular applications of home made compost boosts the community of beneficial microbes, which defend the plants roots against plant pathogens. 
    • Crop rotation also helps suppress soil borne pests by moving their favourite food to a new bed every year.  They are not given enough time to establish and become a significant pest.
    • Exclusion netting stops birds digging up worms in your Ecobed, and takes the edge off hot sunshine with a 20% shade factor.