How to sow green manure crops

Sowing green manure crops
  • It’s important not to leave a garden bed bare over winter. The rain compacts soil which reduces aeration, and bacteria and fungi find it hard to survive.
  • Green manures are annual, fast-growing crops, designed to build both organic matter and nitrogen levels to improve the soil. The benefits include:
    – providing habitat, nectar and pollen for beneficial insects
    – improving water, root and air penetration in the soil
    – smothering persistent weeds
  • There are many green manure crops you can choose from.
  • Broadbeans is one which fixes nitrogen in the soil and gives you an edible crop as well.
  • Mustard aids in the control of wireworm which can affect root crops. Mustard is a brassica, so it’s best not to plant brassica crops like broccoli or kale in the same bed afterwards because brassicas can fall prey to the fungal disease, club root.
  • Buckwheat is a good green manure crop because its flowers bring in the beneficial insects, but it’s not a prolific plant and there’s not much to dig back into the soil.
  • Blue Lupin is one of Rob’s favourites. Buy bulk seed from a garden centre or home handyman store.
  • Oats is another of Rob’s preferred green manure crops. It produces masses of foliage and roots. You can buy the seed from a feed supply store.
  • Rob broadcasts the lupin seeds generously over the soil in one patch, then the same with the oat seeds. Don’t mix the seed. They grow best on their own.
  • Then with a rake, roughly mix the seeds in with the soil. There’s no need to cover the seed with another layer of soil.
  • Water it all in well.
  • When you have about a 10 per cent showing of flowers that’s the time to cut them down and dig them into the soil for a maximum nitrogen boost. If, however, you leave the crop till it’s flowered fully, and then cut it down, it will provide your soil with carbon rather than nitrogen, which is also great.
  • If you don’t want to plant a green manure crop, do cover your bed with something like leaf litter, or seaweed from the beach.
Companion planting around onions
  • We planted our winter onions 7 weeks ago while the soil was still warm. And now that it’s more wintry, we can plant our violas around them.
  • Onions don’t like competing with weeds. Violas are the perfect companion as they spread around the onions, smothering weeds, but not competing for the nutrients from the soil.
  • Violas bring in the beneficial insects and the flowers are a great addition to salads.
Hilling up leeks
  • Keep up the practice of hilling up your leeks every week or two by pushing soil down from the mound in the middle and fluffing up the soil on the sides. This ensures lovely long white stems.


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