Make worm compost

How do you make compost if you have little or no garden? The answer - make worm compost instead our to kitchen scraps. You only need a small container that can go in a garage or porch.



Indoor gardeners use worm casts to top dress potted plants and containers. Outdoors it can be sprinkled over seedbeds, used in the greenhouse and in compost mixes. Worm casts are rich in nutrients and hold lots of water.

Worms can easily make compost from organic household and kitchen waste. This page details how to make a small worm composting factory. You can make the following:-

  1. Worm casts for making good potting compost.
  2. Worm tea for liquid feeding;
    and if you want to go further and farm the worms in the garden, then ...
  3. Worms themselves are a product saleable to anglers, zoos perhaps, and recycling schemes etc... or you could grow eathworms to boost the population of your garden worms. Good breeding worms are saleable to other worm composters.
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Types of worms:-

The earthworms you find in soil are not normally used in specialised worm composters. They are good at burrowing but when it comes to eating organic waste Red Worms are the gluttons. Reds haven't the strength to burrow into soil and usually die in the garden.

Worm Casts:

After being eaten and digested the material that is voided forms the worm cast. These can be formed on top of or under the surface. A worm cast pile looks like a black grannular jelly. Tap one side of a moist heap of worm casts and the whole heap shakes.

The final casts may have been digested many times by the worms. This cleans up the matter by promoting useful microbes. During the process mucilaginous substance is added giving the casts a high water holding capacity and properties that bind soil particles together. The stable soil crumbs improve soil porosity and drainage.

The process also reduces the size of mineral particles and solubilises soil calcium phosphate, making phosphate and other minerals more available to plants.One analysis of worm casts gave: N 2.2% - P 2.2% - K 1.5%.

May I suggest mixing a small amount of Bone Meal into the worm feed. The worms will convert this into more readily available nutrients useful for feeding seedlings perhaps, but in small amounts. See Organic Fertilizers.

The casts are a highly beneficial product that can among other things be used to top dress pot plants, to make potting compost, augment seed drills. They create healthy conditions for root growth.

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Worm Tea:

This liquid accumulates in plastic worm composters that retain the moisture evolved during decompostion. It is higher in nitrogen and phosphates. It can be diluted and fed to plants or used as a compost activator. It can also be mixed with concentrated comfrey liquid to balance the nutrient composition .

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Make Worm Casts and Worm Tea:

I recommend modula worm composting units like the Can-O-Worms (available in UK on this link) which I have used, which is made of recycled plastic, and comes with all you need to get started.

Modula worm units have distinct advantages over a single compartment worm buckets. In the latter it is difficult to seperate worms when the bin is full. The following describes setting up of stacked modula units.

You can make worm compost with Worm Bin Factory which is a similar design available in America.

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How the Worm Composter Works:

Getting Started

The worm tea perculates down to collect in the bottom 1st module which fits onto supporting legs. It has a tap for pouring off the worm tea. The modules above have a contain the compost and have a riddled base.

  • Start by placing a biodegradable cardboard sheet on the floor of the 2nd module.
  • Soak 2 blocks of Coir Fibre in an 8 litre bucket of water and empty the fibre into the 2nd module.
  • Place the worms which usually come in a ball of worm casts on top of the fibre and cover with a soaked sheet of recycled wool or moist newspaper.
  • Cover with the top lid is put on to keep everything dark and aid moisture retention.
  • A little later (don't let the worms go hungry or they'll want to move to new quarters) the moist cover can be lifted and the first layer of well-chopped food spread over half the surface. Much of the food will be kitchenscraps and similar waste. Replace the moist cover and the lid.
  • The process continues with regular feeding.
  • The worms turn the organic matter into black worm casts which quickly cover the surface. The worms work their way up following the food.
  • A sign of healthy worms is seen when you remove the damp cover and observe several worms immediately drawing back into cover. A little probe should reveal many more worms - but avoid handling worms.
  • When the 2nd module is full the 3rd module is placed on top and feeding begins in the 3rd module... and so on. ( - NOTE: avoid overfeeding see below)
  • Some worms will re-work the darker matter underneath.
  • When the worms have reached the top of all the modules, the 2nd module will be ready to empty of its worm compost. Then it can be placed on the top and food added as before.
  • When all modules are full the worms should all be feeding at the top leaving the lower 2nd and 3rd modules empty of worms. Now you can empty the worm compost in the lower modules without loosing worms and still avoid the painstaking messy task of separation.

In dry conditions the worms may withdraw to deeper levels.

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A few problem areas to avoid:

It is important not to put too much food out at once. This is the biggest source of problems, that may lead to smells and other pests. Feed in small amounts regularly and use soft organic matter.

You can place food in small pockets in the compost and cover over, or place it on top and cover over with a matt. The cover deters fruit flies and vinegar flies and encourages worms to feed.

It is also important to keep the worms moist - for example, check them in dry weather.

Check the bottom module does notfill up with water. Although the Can-O-Worms has a central cone to help worms crawl out, any that die in the liquid cause a smell. This may happen when only the first module is operating and the worms are nearer to the bottom. Later on as the food gets higher up the stack, you will find virtually no worms down below.

While worms are settling down some may try to escape. Concentrating a large ball of worms into a small space may be a factor. They may also be searching for food. Placing a light source over the worm bin will keep them inside.

Don't add horse manure from animals treated with de-worming medication.

Don't add quick lime (CaO) to neutralise acids, instead use calcium carbonate, crushed egg shell, or calcified seaweed.

The worm composter has few problems; it should not smell and could be kept in a garage or house porch.

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Seperating worms from worm compost:

There should be very few if any worms in the lower module and certainly all food should be gone from there by thetime the 2 higher modules are full. The modula system has therefore done the seperation for you. So you will probably decide to except a small loss if the vast majority of worms are actively feeding at the top of the Worm Bin as they should be.

However, there are two well used methods of removing worms from the casts which may be useful if you are farming worms in larger open beds or changing bedding in worm breeding boxes. 
1 - Ensure all food is removed from the worm casts and leave them exposed to the light. Place food next to the casts then cover the food and the adjacent third of the casts in darkeness. The worms should move into the new food and leave the casts free to be removed.

2 - Make a mound of the casts, expose to the light and scrape off the outer layersof worm casts layer by layer. Each time you scrape off castings the worms will move deeper into the mound away from the light and you'll be left with a ball of worms and seperated castings.

The worm compost can be stored in a black plastic bag, but not for too long as it will continue to break down.

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Recommended worm bin: the Can-O-Worms - available in U.K. on this link

The Worm Chalet is similar with an advanced design available in America

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