Green manures are a natural way of improving soil, says Gardening Editor Ruth Hayes
I sowed a batch of green manure in the autumn to help replenish the soil in our raised beds after their contents – onions, shallots, broad beans – had been harvested.
They grew vigorously – I may have sowed them a little too generously – and needed digging in so I could prepare the beds for springtime planting in a few weeks’ time.
After digging in the plants I covered them with a thick layer of compost and will leave the soil to break down and settle for several weeks before planting any crops.
Green manures are an easy way of improving the nutrients and structure of your soil.
Depending on the variety, they are usually sown on empty soil between March and November and left to grow. Most green manures are varieties of legumes and rye and help to fix nitrogen in the soil.
Green manures have many benefits, apart from improving the soil. Their roots act as anchors, preventing soil being washed away during heavy rain, and their leafy growth smothers weeds. The plants also provide habitats for beneficial insects and amphibians that will eat insect pests.
They can also be sown as companion plants to distract pests away from valuable crops. However, be aware that perennial green manures such as forage rye can re-grow after being dug in and may need to be covered with a layer of black plastic to stop them coming back.
If sown too thickly they can also take a long time to rot down after being dug in, so you may need to remove and compost some of the above-ground growth instead of leaving it in situ.
- To help the greenery break down well after digging it in, cover it with a generous layer of well-rotted compost or manure. This will also help to enrich your soil.