How to plant onions and leeks

  • If you sowed your onion and leeks seeds when we did, they’ll be big enough now to plant out in the garden. It’s best to get these seedlings in while the soil is still warm.
  • Onions and leeks like free draining, friable soil, so add plenty of compost.
  • Onions, however, are planted completely differently to leeks. Plant onions on a mound because they need extra good drainage, and leeks in a trench so you can backfill them as they grow to encourage long white stems.
  • For both onions and leeks alike, wash all the soil off the seedlings in a bucket of water, to which we recommend you add a couple of capfuls of liquid seaweed fertiliser. Seaweed fertiliser gives seedlings a boost and wards off any diseases.
  • Then with a pair of scissors, cut off the tops of the plants to about 5 cms and trim the roots (gives seedlings a better start).
  • In a 1-1.2m wide bed you’ll be able to create two trenches of about 20-25 cms deep for the leeks. In the same width bed, you’ll get two mounded rows about 20 cms high for the onions. Pat the mounds for the onions down firmly.
  • Rob uses a dibbler (also known as a dibble or dibber or dibblet) to make holes in the soil for the seedlings. He plants the leeks 10 cms apart (which is quite close but he’ll ultimately harvest every second plant as baby leeks when they grow).
  • Plant onions 20 cms apart. Organic onions will grow large and need plenty of space. Ideally the bulbs shouldn’t ever touch each other.
  • To keep onion and leek plants in the best of health, give them a spray of seaweed fertiliser every couple of weeks.
  • After planting, sprinkle on something like our Morganics fertiliser. The phosphorus in this fertiliser helps bulbing veges like onions and the minerals in it are good for the leeks. Apply again after about 6 weeks.
  • Water the seedlings in well. If the weather remains dry, water every 2-3 days to get them growing.
  • It’s absolutely essential to keep onion and leek beds weed-free. Onion and leek plants can’t compete with weeds.
  • The only real companion plant for onions and leeks is viola. Viola covers the soil but doesn’t take any nutrients away from the plants. Leave planting of viola for another 3-4 weeks though, when the weather is cooler.
  • Now’s a good time to gather up garlic and shallot bulbs for planting out in a month’s time. Purchase from an organic store or a Farmers’ Market (check at the Farmers’ Market that the bulbs haven’t been sprayed with an anti-sprouting powder however).

Camera: Jarod Murray
Editor: Thomas Asche
Production equipment and post-production services provided by The Black Forest Breathes