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

Green manure crops could fill empty space on allotments and boost harvests,

If you’ve spare room on your allotment, or 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?


View this post on Instagram


Happy post this morning 😍 no idea what I’m doing so better get reading 😂#greenmanure #improvethesoil

A post shared by Alison barham (@alisonbarham17) on

They are 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, (they’re known as good nitrogen-fixers) that can be ploughed back into the earth.

Which crops make good green manures?


View this post on Instagram


Queuing up for these lavender-blue flowers. Phacelia tanacetifolia (Fiddle Neck, Scorpion Flower, Blue Tansy) is a magnet for all sorts of pollinators who can’t get enough of these pretty blooms. This tall annual – it grows to about 1m (3.5 feet) in height – is a member of the Borage family and is often used as a green manure. Borage flowers can renew their nectar in a matter of minutes – hence the constant stream of visitors. (Other flowers can take up to a day to replenish theirs). These pretty blooms also make great cut flowers, so plenty of reasons to grow this plant.💜🐝 . . . #bluetansy #scorpionflower #fiddleneck #phacelia #phaceliatanacetifolia #greenmanure #cutflowers #cutflowergarden #cutflowersfrommygarden #cutflower #cutflowerpatch #cutflowergrower #cutflowergardening #gardenersworld #gardening #gardeninguk #gardenplants #gardenstagram #englishcottagegarden #gardenflowers #gardengreatorsmall #gardeningideas #cottagegardening #cottagegardenflowers #cottagegardenplants

A post shared by Yvonne (@theplantedterrace) on

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?


View this post on Instagram


I planted a cover crop of clover, alfalfa and oats. Great green manure to improve the soil quality.

A post shared by Angela Bauman (@innisfail_fresh_produce) on

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 up decomposition. Leave them a few days to wilt and then dig them into the soil.

Longer term crops such as alfalfa, red clover and trefoil can be left in the ground for a year and clipped from time to time to stop them from going woody. They are ideal for soil that’s been overused and needs to rest.

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, which can help pollinate crops, 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.

What if I want to wait?

If you have no crops to fill the space, cover the green manure-treated bed with cardboard or landscape fabric to keep the nutrients from the green manure in, which will give you a great seedbed to sow seeds in come spring.

What else can I grow to help my crops?

Try growing comfrey, which absorbs nutrients and minerals and can be made into a liquid feed. Just cut it down to the ground, fill a bucket with the leaves and stems of the plant, packing them in tightly and then filling the bucket with water.

Set it aside for three weeks (but keep it away from the house as it pongs when it decomposes), then strain off the liquid into a container with a tight lid. When you want to feed your plants, dilute the liquid with water at a ratio of around 10:1 and feed your plants weekly into autumn.

The following two tabs change content below.

The Press Association

News from the Press Association - the national news agency for the UK and Ireland

Leave a Comment!

Not a member?

You need to be a member to interact with Silversurfers. Joining is free and simple to do. Click the button below to join today!

Click here if you have forgotten your password
25th Jul 2020
Thanks for voting!
Have any readers some tips for clay soil. Soil that can be rolled into balls and sticks to shovels and spades and has to be removed with a trowel. I am too old now to run a pottery !! Have tried digging in soil improver, horse manure etc.etc. but the clay just laughs it off..

Community Terms & Conditions

Content standards

These content standards apply to any and all material which you contribute to our site (contributions), and to any interactive services associated with it.

You must comply with the spirit of the following standards as well as the letter. The standards apply to each part of any contribution as well as to its whole.

Contributions must:

be accurate (where they state facts); be genuinely held (where they state opinions); and comply with applicable law in the UK and in any country from which they are posted.

Contributions must not:

contain any material which is defamatory of any person; or contain any material which is obscene, offensive, hateful or inflammatory; or promote sexually explicit material; or promote violence; promote discrimination based on race, sex, religion, nationality, disability, sexual orientation or age; or infringe any copyright, database right or trade mark of any other person; or be likely to deceive any person; or be made in breach of any legal duty owed to a third party, such as a contractual duty or a duty of confidence; or promote any illegal activity; or be threatening, abuse or invade another’s privacy, or cause annoyance, inconvenience or needless anxiety; or be likely to harass, upset, embarrass, alarm or annoy any other person; or be used to impersonate any person, or to misrepresent your identity or affiliation with any person; or give the impression that they emanate from us, if this is not the case; or advocate, promote or assist any unlawful act such as (by way of example only) copyright infringement or computer misuse.

Nurturing a safe environment

Our Silversurfers community is designed to foster friendships, based on trust, honesty, integrity and loyalty and is underpinned by these values.

We don't tolerate swearing, and reserve the right to remove any posts which we feel may offend others... let's keep it friendly!