Life

Gardening tips: Empty space on your veg patch? Boost soil with green manure crops

Space on a vegetable patch can be used for a green manure crop
Space on a vegetable patch can be used for a green manure crop Space on a vegetable patch can be used for a green manure crop

IF YOU'VE spare room in your garden for crops that will fill empty spaces and boost your soil, consider plants that can turn into green manure. You may have harvested potatoes and onions, but plant some fast-germinating replacements and you'll stop weeds from growing, keep the goodness in, and help soil structure.

:: What are green manures?

Crops that can help improve your plot's structure, stop nutrients from being washed out by rain, and provide good ground cover to stop weeds emerging. Those that belong to the pea and bean family (legumes) for example, in summer, can store nitrogen in their roots, that can be ploughed back into the earth.

:: Which crops make good green manures?

At this time of year they include mustard, fodder radish, fenugreek, buckwheat and phacelia, which can be slotted in in six to eight week gaps when the ground is cleared between crops. Some sown in early autumn, including winter beans, grazing rye and winter tares, will last through the winter and can be dug into the soil when it warms up in spring.

:: How long do they take to grow?

Some, such as mustard, are fast-germinating. Two weeks after sowing you'll find the ground covered with small seedlings, and after six weeks, these can be chopped and folded into the soil to add nutrients.

Fenugreek is another nitrogen-fixer for summer, really fast growing and its bushy plants are great for suppressing weeds. It can be planted in late spring or summer and grown for up to three months.

:: When do I cut them down?

Chop the fast-growing ones when you need the ground back. Just dig them up, chopping up the leaves and stems as you go to speed decomposition. Leave a few days to wilt, then dig them into the soil.

:: What benefits do they provide?

Clover, fenugreek, winter beans and alfalfa are good nitrogen-fixers, storing nitrogen in their roots, while clover and phacelia flowers are a magnet for beneficial insects, so leave some to flower. Italian ryegrass and buckwheat have root systems that will help break up heavy ground.

:: When can I plant crops in the space again?

A few weeks after you've dug in your green manure, you can sow late crops such as onion and garlic.