Much ado about mustard

21:01, Jun 03 2013

It's amazing how many times, as an organic gardener, you run into the word "manure". Or as giggling children around the world know it, poo. In biodynamic gardening, the poo of cows is shoved into cow horns to ferment, poo of any herbivore can be put on a compost heap to get it going, poo can be shovelled into garden beds and dug over to prepare for planting. Poo is the gold in that thar garden.

But what if you don't want to be handling, albeit with gloves on, poo?

Then you turn to green manure. Which sounds horrible, but it's not. Green manure is simply another way of saying: growing a quick, easy, leafy crop that will add nutrients to your plot when you dig it in and let it rot.

I could bore the teeth out of your head with discussions about which green manure, also called "cover crop", is best to add nutrients to the soil, but I won't, because I simply don't know that much about it, but I do know this: some green manure crops, like broad beans and peas, have the magical ability to fix nitrogen, that most valuable of nutrients, to their roots, which is released into the soil when the plant rots down.

Last winter's green manure growing in the front garden, with the chooks digging it in for me

I'm growing my favourite green manure crop - mustard - in the front garden, as I carry on turning it from a weedy ornamental garden into a functional edible garden. Over the past couple of years we've been gradually removing weeds that had overrun it such as jasmine and ivy and agapanthus to make space for edible garden, and improving the soil. I have only grown crops in here during the spring and summer so that I can give it a rest and some green manure and compost over the winter months. So far the soil is turning light and friable and dark, not the hard grey clay that it was the first time I stuck a fork in it. This means my strategy is working! Just before the mustard flowers, I will cut the plants down and hoe them lightly into the topsoil. They'll rot down, adding nutrients and organic matter to the soil, helping to break up that clay better. Also in spring, I will top this off with more compost.

I'm thinking this will be my potato patch in the spring. Planting spuds is another good way to break up soil.

Do you use green manures? How do you use them?

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