Earthworms - An Essential Part of Any Vegetable Garden

, written by gb flag

Worm curled up

I suspect that many of us, at some point, ask for a bit of help in the garden. How aware are we, though, of the help that is already there? Worms are so familiar that it’s easy to take them for granted, but look at the work they do on the vegetable plot and you may never want to use a rotovator again.

Soil Formation

We all know that a healthy compost heap is writhing with worms, working their way through the kitchen and garden waste to help create organic matter to feed our soil—these are mostly brandling worms, recognised by their red, stripy appearance—but I’m talking about the worms which, if your soil is good, you’ll find in large numbers throughout your vegetable plot. How useful are they?

Well, first, they’ll be munching on leaf fragments and other plant debris that accumulate on the soil surface. Research indicates that, having passed through worms, these bits and pieces are broken down more easily by microbes. Result? Humus! That black gold beloved of all organic gardeners is produced more quickly with the help of worms than by microbes alone.

Nutrient Cycling

With worms having little to do but eat, they shift a surprising amount of material. One study on forests came to the conclusion that worms buried over 90% of the plant debris left on the soil surface. Another indicated that an impressive forty tonnes of soil per hectare were brought to the surface in worm casts in the course of a year.

This is great news as worm casts tend to be very fertile, holding more calcium, iron and phosphorous than the soil around them. They also contain significant amounts of nitrogen and help to stabilise carbon, reducing the release of carbon dioxide from the soil. The small particle size in the casts means they can even hold more water.

The net result is that more organic matter and nutrients are incorporated into your soil, minerals from below are brought up into the root zone and your veggies have access to more moisture.

Worm in the soil

Water absorption

Of course, worms also burrow, and not all in the same direction. Epigeic species burrow in the litter on the soil surface; anecic species live in vertical burrows that can descend several feet. Endogeic species burrow below the surface in horizontal or random lines. Aristotle described worms as "the intestines of the soil", which is a good way to regard the passages they create. Burrows open up the soil to air, bringing oxygen to plant roots, and create pathways for water and roots. The presence of earthworms has been shown to have a notable effect on the amount of water a soil can hold and on how fast it sinks in.

Not all worms are good

It’s possible that by now a few of the scientists among you are in danger of apoplexy, so I should add that you can’t assume that all worms do all of the above. The Encyclopaedia Britannica numbers worm species around the world at over 1800 and they’re not all doing the same thing. While some open up the soil, for example, others actually compact it. Surprisingly, bringing earthworms into an environment isn’t always a good thing—species introduced to otherwise wormless North American forests are causing problems by destroying the deep surface litter.

However, in normal garden circumstances, you don’t have to start rounding up worms and quizzing them on their usefulness. Barring an exception like the New Zealand flatworm, which is appearing in the UK, you can assume that all your garden worms are playing their own particular part in the creating nutrient-rich soil to feed your delicious veggies.

Looking after worms

Worms in compost

Given their activities, it’s a good idea to encourage as many as possible to hang out in your soil, so my first suggestion is to dump the rotovator. Agricultural research has shown that the more soil is tilled, the fewer the worms are in it and, despite rumours to the contrary, worms cut in half do not grow into two worms. It’s true that, in some circumstances, one half might survive, but on the whole you can assume that a bisected worm is a dead worm.

Digging also presents a clear and present danger to them, though on nothing like the scale of a rotovator, and worm safety is one of the reasons I’m a great advocate of No-Dig beds which leave soil undisturbed. If you must dig, using a garden fork rather than a spade is less likely to damage worms.

Bear in mind, too, that worms eat organic matter and, if supplies drop off, they will vote with their contractile tissue and move elsewhere. They also need moisture, which is why in dry weather you’re likely to find them in the damp soil under stones or wound into a tight ball. It’s their way of protecting themselves from heat and dryness until conditions improve.

The best answer to keeping them happy is to look after your soil. Ensure that it’s well fed with compost and spread with mulch, and don’t dig unless you have to. Not only will it be good for your plants, but the organic matter and improved water retention will make the worms want to call your garden home.

Experiment and enjoy... and if you find a particular combination you love, why not add a comment to share it below?

By Helen Gazeley

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Show Comments


"Love the article. I have a worm farm with lots and lots of composting worms, and I am wondering about putting some of them into my three new raised beds. They are quite large beds and will only be used for veggies, so would the worms be happy in there?"
Mary Galea on Friday 31 May 2013
"Yes, by all means, put some in your raised beds. In fact, that's the advice I have read by worm farmers since worm farms can become overcrowded at one point, especially if your worm farm is the tower style and you've used up all the trays."
florence krohn on Friday 7 June 2013
"I use worm casts for making seed compost mixed with peat and some silver sand. Excellent growing medium only used for special plants due to the time it takes to collect."
George Ewings on Saturday 1 February 2014
"No worries about cutting garden worms with tillers, rotovators or spades. They reproduce fairly quickly and will repopulate proportionately to the available food, which is compost and mulch. The dig against them as non-native species eating forest duff and surface litter is grossly overstated, largely from animal rights activists trying to cast aspersions on fishermen using worms. They came to North America in potted plants and are being spread by birds. Get over it! They are here to stay."
Jim McNelly on Saturday 31 January 2015
"the earthworm has five hearts"
tungane kani on Tuesday 24 February 2015
"Whenever I start a NEW bed, I double dig it, adding lots of home made compost, and worms, as I go. If done properly, you'll never have to dig your garden again!"
Annie Gaddis on Thursday 9 April 2015
"Keep feeding the soil with organic matter and the worms will love you for it - and it will show in the quality of the soil you grow in!"
Ben Vanheems on Monday 13 April 2015
"My soil varies from adobe like to compost with mixture of both. I have a red wiggler worm farm for composting and worm tea but realize that the red wrigglers only survive on moist surfaces and don't go deep as regular earthworms. Are knight crawlers anymore efficient or advantageous over the regular worms? Are certain type of worms better for this coastal southern california area."
Manley Kiefer on Tuesday 31 July 2018
"Unfortunately I don't have any experience of which worms may work best in different climates. Certainly in a warm climate keeping composting areas cool will be a priority, which is partly helped by ensuring the dimensions of the compost heap are generous (so they don't quickly overheat) and perhaps shaded too. Regular watering may be necessary if your compost heap is drying out, to keep it all rotting along nicely and to keep the worms happy."
Ben Vanheems on Tuesday 31 July 2018
"i live in vermont, where can i find some earth worms? can i buy them?"
Ernest Silvia on Friday 7 September 2018
Ernest Silvia on Friday 7 September 2018
"Hi Ernest. Earthworms naturally occur in the soil, so the best way to encourage them in your garden is to simply enrich the soil with plenty of organic matter such as compost or leaf mold, so they have lots of goodness to work with. You can buy earthworms and other worms to help with composting, but these are specifically for making compost and not general introduction to your soil - e.g. search 'Earthworms 4 Sale'."
Ben Vanheems on Monday 10 September 2018
"I have worm bins (which i KNOW contain red wigglers), and raised beds. At times in the past, i have brought some of the worms from the bins and put them into the raised beds; and vice versa, when it gets cold. I assume many of the worms came into the raised beds on their own, but I am not sure. I don't know how to tell the difference, visually, from red wigglers and garden-variety earthworms. I can't find any images online of them together. How can I tell the difference? "
Linda on Friday 10 May 2019
"I have worm bins (which i KNOW contain red wigglers), and raised beds. At times in the past, i have brought some of the worms from the bins and put them into the raised beds; and vice versa, when it gets cold. I assume many of the worms came into the raised beds on their own, but I am not sure. I don't know how to tell the difference, visually, from red wigglers and garden-variety earthworms. I can't find any images online of them together. How can I tell the difference? "
Linda on Friday 10 May 2019
"Common earthworms are much fatter and paler - like a pale flesh colour. They are generally bigger. The red wrigglers are usually noticeably redder. Common earthworms go by the Latin name Lumbricus terrestris. Red worms go by the Latin name Eisenia fetida. So you should be able to look them up to get images of both. Hope this helps."
Ben Vanheems on Friday 10 May 2019
"Love your article on worms. Since I put in raised beds, my worm population has increased. I use newspaper around my llants and then mulch with straw. They lovethe newspaper."
Cathie Maneval on Sunday 16 June 2019
"Fantastic to hear that your earthworm population is on the up. All that lovely mulch will certainly be helping,"
Ben Vanheems on Monday 17 June 2019

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