This page is intended to give additional information and advice on collecting and maintaining a healthy colony of composting worms. insturctions for building your own wormery can be found here
Before starting, it is important to understand a little about worms so that you can provide the best environment and food for their needs; the healthier your worm colony is the more efficient it will be at processing your waste.
Worm habitat (the wormery)
The worms most commonly used in wormeries are litter dwellers; they live amongst dung, fallen leaves and other decaying material above the soil surface and are seldom seen within the soil itself.
As the worms digest the decaying material they create tiny worms castes (worm poo). In the natural environment the worm castes are quickly broken down and enrich the surrounding soils. In a wormery we collect and store the worm castes, creating a nutrient rich compost to benefit the soils and plants of our choice. A nutrient rich liquid also drains slowly from a healthy wormery and this (when diluted) is a fantastic liquid feed and health tonic for plants.
The wormery we built (and provided instructions for) replicates the worm’s natural environment- a thin surface layer of worm bedding covered in decaying material (worm food).
It’s stacking design enables maximum surface area whilst remaining compact and moveable. It can also be extended (upwards) to provide space for several layers of worms to be busily munching and composting at once. Your worm population will swiftly breed and inhabit each new layer.
We’ve experimented with 2-5 layers and all have worked well but it is best to start with just 2 layers and allow your worms to settle and breed before adding further layers.
2 layer and 5 layer wormeries can be seen in the diagrams below:
Increasing the number of layers simply adds extra surface area for the worms to live and feed within. This means your wormery will have a much greater capacity for worms and will be able to process much more organic waste. A 2 layer wormery may eventually support 2,000 worms whereas a 5 layer wormery can support a huge population, busily chomping your waste and creating compost. The most important factor is to ensure that every layer has adequate air flow and drainage.
Adding extra layers to your wormery
To add an additional layer to your wormery simply add another feeding box on top once it is fully established and your worms are multiplying well, then replace the lid on the top box . (see diagram of 5 stack wormery above). Place a small amount of compost in the bottom of each additional feeding box so that the worms are encouraged to migrate upwards into the new feeding area. Remember to make sure that your bedding box (with its circle of drainage holes) is always the bottom box in the stack.
Suitable worms can be collected from the top layer of an existing compost heap or bin (they will only be located in the top few inches so there is no need to dig deep). If you know someone who already has a wormery they can provide you with a starter colony. Ideally you want to start with several hundred worms so that they breed rapidly. Try to avoid using earthworms- commonly seen battling blackbirds and leaving worm castes across the lawn- they are not suitable for wormeries.
Don’t worry about other invertebrates which are likely to be mixed in with your worms- they will help create a healthy ecosystem within your wormery. Our wormery often has woodlice, tiny slugs, spiders and millipedes in residence.
It is also possible to purchase composting worms on the Web. Native worms commonly sold for wormeries include:
- Red Worm (Eisenia andrei) also known as red wrigglers
- Tiger Worm (Eisenia fetida) also known as brandlings, Manure Worm
- Dendrobaena (Eisenia hortensis) also known as Dendras, European Nightcrawler
We suggest avoiding the purchase of Dendrobaena (which are also often bred for fishing bait) as they are considered an invasive species and may impact on the populations of other invertebrate species should they escape from your wormery.
You can find links to sites which sell composting worms and provide further information on wormeries on our links page
Worms can live for about one year in the wormery. New worms are born and others die all the time in your wormery. A worm’s body is about 90% water so they shrivel swiftly and become part of the compost.
Worms are hermaphrodites (they are both male and female at the same time). In order to mate still requires two worms. The worms line up in opposite directions near their central band, which contains some of the sexual organs and exchange sperm cells. The worms then go their separate ways.
Several days later, the worms releases eggs which come into contact with the sperm cells and form a cocoon. The cocoon separates from the worm, the eggs are fertilized and 2-5 baby worms begin to develop within the cocoon.
The tiny worms live in the cocoon for 3 weeks (or more during cooler times of year). upon hatching they are white in colour and about 5mm long. When you see these tiny worms spreading throughout your wormery you know your colony has settled and is breeding well.
Feeding your worms
Make sure you chop up the food you add to your wormery. Worms have tiny mouths and no teeth- they will process smaller chunks much easier than whole items.
Suitable foods include tea bags, fruit & vegetable peelings, egg shells and coffee grounds. You can also add processed and cooked food to a wormery – but avoid adding in any quantity, particularly until your wormery is well established as uneaten cooked foods can get smelly . You should avoid adding onion skins, citrus and very spicy or oily foods- worms don’t like these. Don’t feed salty foods to your worms- salt will cause them to dehydrate and die.
As well as food waste, you need to add about the same mass of carbon rich material such as ripped up paper, cardboard or wood chip. So to keep it simple- for every handful of green waste make sure you add another handful of brown waste. Their food layer should remain damp but not so wet that you can squeeze liquid from it. If its too dry- sprinkle with water, if too wet- add more newspaper.
Keeping your worms healthy
Composting worms do not like to live in an acidic environment. If you add citrus or other acidic foods to your womery try to ensure you also add egg shell or a small amount of chalk dust regularly to balance the PH levels.
If your wormery is too dry sprinkle or spray some rain water into each dry layer. The cardboard and newspaper should always be slightly damp. If your wormery gets too wet it may start to smell (due to anaerobic decomposition) and your worms may try to escape- you can remedy this by thoroughly mixing in more cardboard or paper until the excess moisture is soaked up.
Composting worms operate best at temperatures between 10 and 30 degrees centigrade. If they get too cold they will become dormant and you should stop feeding them until the temperature rises. If your worms get too hot they will die- make sure the wormery is shaded from full sun in summer. You can encourage them to keep working through colder weather by wrapping the wormery in old carpet or relocating them to a warmer location such as a shed or outhouse (they are equally happy in a kitchen where they will remain at peak breeding and composting levels all year round).
Harvests from your wormery
When your bedding box is full of compost made by your worms you can remove it from the stack. Scoop off the top few inches and keep it to one side- this is where most of the worms will be lurking and you’ll want to return them to your wormery.
You can use your harvested compost immediately, or you can store it in a compost sack. The compost can be directly mixed with your potting soil or garden soil as a soil additive, which helps make nutrients available to plants. Or, the compost can be used as a top dressing for your indoor or outdoor plants.
Do not plant into pure worm compost- it is too rich in nutrients and will burn your plants. I use an approximate ratio of 1:4 (worm compost: garden soil) for seedlings and 2:4 (worms compost: garden soil) for established plants.
Making compost tea
You can also make “compost tea” with your worm compost. Simply add a handful of compost to your watering can. Allow compost and water to “steep” for a day, mixing occasionally. This tea does not need diluting- just apply directly to your plants.
You can make large quantities of compost tea by stuffing an old pair of tights with compost and immersing them in a water butt or dustbin. Adding a good dollop of molasses and giving it a good stir over a few days will send all the micro organisms into a flurry of activity. Your compost tea will froth like fermenting beer and smell quite funky- this is a very good sign- the mircrobial action improves the availability of nutrients for your plants.
This is the biologically active, nutrient rich liquid that drains from the bottom of your wormery. It is a wonderful health tonic and feed for your plants. Dilute it at a ratio of 1 part liquid gold to 10 parts water. It can be used to water your mature plants once a week during the growing season. You can also use it as a foliage spray as most plants also absorb nutrients and moisture through their leaves. If feeding cacti or seedlings dilute your liquid gold at a ratio of 1:20 as these plants are more sensitive to nutrients.
Your worms will swiftly breed when temperatures are above 10 degrees C. Once your wormery has been operational for 6 months to a year you should see worms present at all stages of development. You can now start taking the occasional handful of worm filled bedding to colonise other wormeries or compost heaps. You can also use your worms as fishing bait, ferret snacks, lizard food or as a treat for you garden birds.
My favourite option is to donate worms to someone else so they can start a wormery- ideally it takes several hundred worms to get started. Alternatively you can make a small wormery from a 2L plastic bottle- these keep kids of all ages entertained.
That’s it- you’re ready to go! If you need more advice on keeping, sourcing or sharing composting worms please contact us– we’ll try to help. Alternatively you come and see our wormery in action during any of our open days or events. They’re always chomping busily away on discarded tea bags and carrot tops in their new wormery under the Hemlock trees.
Cornell University’s Vermiculture for Schools page,
Natural History Museum’s Invertebrate Archive