Green manure crops are usually cover crops, used to ‘cover’ the soil when not in use over winter and, most importantly, to replenish the soil after giving out all that summer goodness to your crops.
It is a loving treatment for your garden that we highly recommend here at Grow Inspired. It can be easy to forget about the soil’s life cycle – but when it grows your summer plants, it is feeding them all its nutrients and can be left depleted. Just like when you spend all summer enjoying the events, BBQs and festivals, and need to take a well-earned hibernation over winter to restore your energy levels.
Green manure crops are grown to open up the soil, return nitrogen and also break down into the soil to improve its quality and nutritional value. If you are only a summer gardener, this is perfect for you because, while your garden is resting, it is also getting added benefits.
If you like to have home-grown nourishment all year round, my handy tip for you is to have one garden bed in your rotation with a green manure crop over winter to replenish it, which is what I do at home.
By adding the plant material back into the soil, you will increase the organic matter it contains as the plants decompose, which in turn will release plant nutrients such as phosphorous, trace minerals, potassium and nitrogen that will be available for your summer plants to feed on. Green manure crops can also increase your plants’ production.
The types of green manure crops are broad beans, lupins (lupines angustifoli), peas, oats, mustard and phacelia to name a few.
Mustard is a quick growing green manure crop. Lupins are also fairly quick at 6 – 8 weeks. Broad beans are slightly longer.
Phacelia is a great bee plant, and usually planted in spring, but could be planted up until the end of April.
The key thing to remember is that all these plants need to be dug in before they flower, otherwise all the good nutrients go up to the flower and your soil will miss out. If you want to keep seeds of these plants, you can grow them elsewhere and admire the beautiful flowers and then collect the seed when mature.
By sowing green manure crops, you are building your soil structure and, as they are dug in, they are feeding all your life under the soil which enables good microbes, fungi and bacteria to keep multiplying. Without organic matter, the life under the soil can die, creating a dead soil that has no life.
Soil always needs to be replenished to keep the life active which, in the following season, will help the roots of your crops thrive.