When you hear the term ‘green manure’ you probably are thinking that it means fresh poo, but you’re on the wrong track.
What is a green manure crop?
A green manure crop is a great way to revitalise a garden bed that is intensely used. In a very simple term it’s using immature plants to revitalise your soil. So instead of waiting for harvest, you dig the immature plants into the soil to compost down and essentially feed the soil.
For those of us with little space, it’s a great way to breathe some life back into your garden without replacing your soil entirely or spending loads of time giving it a decent break.
Using a green manure crop is not only a great way to restore nutrients it is also a great way to restore balance and get rid of any nasties in your soil, and in sub-tropical climates it’s easy to pick up some unwanted diseases. This technique is called biofumigating, sounds nasty and technical but it’s just choosing a plant that will deter certain pests/diseases. For example a good mix of marigolds and mustard plants dug into the soil will help with a nematode problem.
What are good seeds for green manure crops?
Generally when people talk about green manure crops, they are talking legumes. But there are loads of other combos you can do and it’s worth experimenting with what grows best in your location. Popular combinations include clover, lucerne, peas and beans.
Many seed suppliers sell green manure crop packs which take out all the fuss of deciding what to choose, plus it’s a hell of a lot cheaper to get them as green manure seeds as opposed to getting small packs of this and that.
If you’re a seed hoarder, it’s also another good way of using up seeds that you’ve been storing that may be borderline viable. I usually chuck them in the mix and then I don’t feel like I am wasting them.
How to sow a green manure crop?
I basically scatter the seeds over freshly dug soil and rake over, give it a good water and off you go. It will of course depend on the seeds you choose but if you follow the normal planting directions in terms of the correct depth you should have no problems. You will need to keep the water up to it just like you would your regular vegetable garden.
When to dig in your green manure crop?
I tend to dig in when the plants are just about to form flower buds but it all depends on the type of plant. The plants need to still look healthy, so err on the side of caution and dig them in sooner rather than later.
When can I plant again?
Generally I try to wait around 4-6 weeks from digging in the crop. By the time I plant the seed, dig in the bed and wait for 6 weeks it has been rested for an entire season and it’s ready to roll. I try to also choose a season that is my least productive so it doesn’t feel like I am missing out on growing time. That season is Summer for me (read about my summer planting woes in our hot-humid climate here, here and here), but if I have a bed that isn’t doing particularly well, there is no point adding new plants.
Have you tried a green manure crop in your vegetable garden? Leave a comment below