Composting : Getting Started
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Composting was once the preserve of farmers and gardeners but with the increasing interested in the environment, sustainability and climate change it is now being actively promoted by local Councils and environmental concerned households in order to reduce the waste sent to landfill.
The recycling glass, paper and newspapers has become routine in many households and it is now routinely undertaken for metal cans, plastic, and in many areas, green waste from the garden is undertaken by councils either free of charge or for a fee of about £30+ per year. Councils are increasingly charging for green waste collections as balancing the books at a time of expenditure cuts conflicts with the need to protect the environment.
Organic materials make up about 60% of household waste. Garden waste e.g. grass clippings, old vegetables, leaves, hedge trimmings along with uncooked kitchen waste such as vegetable peelings and outer leaves are frequently composted. The usual advice is that cooked food waste should not be composted as it would attract rats or smell. However with the correct techniques such materials can be composted without problems and one of my ambitions is that more cooked food waste from households, school and businesses be composted on-site.
While collecting organic waste and including it in a municipal composting system saves it being sent to landfill or incineration composting on-site, be it at home, allotment, school or a small business, saves the energy that would be required to collect and transport it to a central site reduces air and water pollution, and saves landfill space. Local composting either by individuals or community groups also means that control and the end product remains with the individual or community rather than one of the large corporations.
In this section we will consider how to get started and in particular the collection and separation of the waste into waste streams depending on the composting method required.
The initial separation depends on the source i.e. garden or kitchen waste. Most garden waste is generated and composted within close proximity so we may not need a separate storage area for compost waste as it may be put straight into the compost bin. However some composting techniques may require the compostable material to be kept in separate browns and greens piles before being placed in the compost bin.
Garden waste includes grass cuttings, trimmed leaves from vegetables, annual weeds (without seeds), grass clippings tree leaves, twigs and sticks, and old pot and vegetable plants. It can also include items specifically grown to compost such as comfrey. It is even possible to compost quite large logs, stumps and other woody items.
Normal garden and uncooked kitchen waste may be composted using a compost heap or bin. Special techniques have been developed to deal with others e.g. grass-boarding for larger amounts of grass or a Hugelkulture mound to deal with logs.
Most of us now use cold composting techniques in a plastic bin. Cold composting does not destroy pathogenswhich means that diseases on plants, that can survive away from the plant, will survive the composting process. The other approach to composting is “hot composting” which produces compost in a much shorter time. It has the benefits of killing weed seeds and pathogens (diseases).
In some cases items that present problems to the home composter such as perennial weeds, hedge cuttings etc may be collected by the Council as part of their kerbside collections or may be accepted if taken to the local recycling collection point. However in many cases there is also a home option e.g. many perennial weeds can be drowned in the garden and then composted. However we can choose to dry or drown our weeds and then compost them.
When considering the composting of garden waste we normally think of composting at home but this aspect of composting could include Community Composting on an allotment, school or housing development or even at a central village location.
Collection of kitchen waste will require a degree of separation depending on the types of waste and the techniques to be used.
- “Conventional” Compost bin, used for cold composting, such as the plastic bins provided under local Council schemes and wide range of bins available for purchase on the internet including wooden bins Wooden Compost bins different types of conventional plastic bin Plastic Compost , tumbler bins which are turned to aerate the contents Tumbler Composters and even metal bins Metal Compost Bins . Most of these bins are used for cold composting and do not produce enough heat to kill germs in addition they often lack a base which allows access to rats and other vermin as well as beneficial composting organisms. – Uncooked vegetable waste e.g. peelings.
- Wormery. Used to compost uncooked kitchen waste excluding citrus and onions.Wormeries
- Sealed vessel Hot Composter such as the Hotbin or Jorra for cooked food waste Composting Food
- Bokashi system an indoor system used to cooked food waste Bokashi bins
To avoid smells and too frequent trips down the garden to the compost bin it is advisable to have a kitchen caddy that can be kept indoors. A separate caddy will be required for each waste stream although I just use two caddies (compost and worms) in addition to taking cooked food waste directly to the relevant cooked food composting bin in a plastic “take away” container which can be washed immediately.
There are a wide range of kitchen caddies available in plastic, pottery or metal. I prefer the plastic as they can be easily cleaned by putting in the dishwasher. Some are quite large but I would suggest the use of a bin that is filled in a couple of days to avoid unpleasant smells. I also put newspaper in the bottom of the caddy to absorb some of the moisture in the food making it easier to tip the waste in the bin.
Some kitchen caddies include a charcoal filter to reduce the smell. If you are considering one of this type ensure that it can be easily removed when washing the caddy. Others have holes in the sides help with ventilation and reduce potential smells but these need the use of a compostable paper or plastic bag. (There is more information on kitchen caddies and the use of compostable bags as a liner to keep the caddy clean at Compostable Bags )
The local Council may operate a food waste collection scheme where they provide caddies for use in your kitchen that are emptied into a larger container kept outside and collected as part of the kerbside collection. Unless you treat the bin as a mini-compost heap and balance the greens and browns added it is likely to smell if collected on a weekly or fortnightly basis.
Other Household waste
Most of the items mentioned above are what are known in composting terms as Greens but to have an effective working bin we need a balance between Greens and Browns. Luckily we have good sources of browns at home. These include cardboard, paper including shredded computer paper, egg boxes the tubes from toilet and kitchen and the bedding from vegetarian pets e.g. chicken and rabbits. Composting is a good final stage in a home identity theft and security programme as it is dificult to get personal information from composted shredded paper.
For a list of items that can be composted click on the link What Can I compost?
Composting at home
Home composting is a natural process that can convert garden and most kitchen waste into a material that can be used as a soil improver, garden mulch, or to top up flower and patio pots. It has the additional advantage of diverting waste from landfill and the cost of collection by the local authority. It is safe to assume that if you are reading this page you either already compost or are interested in composting.
If you are reading these pages I assume that you are interested in composting and probably already compost at home or school. If this is the case it may come as a surprise to you that almost half the food waste sent to landfill from households that already compost could have been composted. Most of us can compost more.
Anything that was once living will compost, but some items, such as cooked food or faeces from carnivores, are best avoided in conventional heaps or bins to reduce the risk of attracting attracting rats or spreading disease. There are special techniques that can be used to deal with these materials which are addressed in other parts of this site. If you are interested in composting please consider composting your cooked food. Adding it to a special composter daily must be better than storing it in a caddy for a week to be collected by the council.
Landfill is expensive, and organic waste breaks down in landfill to produce methane and greenhouse gas. Composted at home the waste decomposes aerobically without producing methane and provides us with a free soil improver in the form of compost plus liquid feeds, e.g. worm wee or compost tea, if we wish to produce them.
Compost can be made simply by adding compostable items to a compost heap or trench. It will compost eventually. Grass mowings and soft young weeds, high in nitrogen, rot quickly working as 'activators', getting the composting started, but without the addition of carbon rich materials such as cardboard or woody items, may produce an unpleasant wet and smelly end product. Details of how to avoid this are given later.
Today when composting is mentioned most people will think of the plastic compost bin available at a subsidised price from the local council. However there are a wide range of alternative plastic bins of varying complexity and costs as wellwooden, metal as a number of more traditional methods of composting.
Composting Area and choice of method
The choice of composting method will depend on the type, and quantity, of materials that you want to compost. While the original intention might have been to just have a cheap compost bin purchased under the local council scheme you can, once bitten by the composting bug, soon find that you have your own Composting Centre trying to take over the garden as you discover a desire to compost additional materials and try different bins.
In this section we will consider select suitable techniques for different materials
Vegetable plants, annual weeds, some grass
Cool or Hot compost heap or bin, sheet or trench composting
Drown, Perennial weed heap or bag
Compost (shredded), Leaf mould bin or bag, or use as part of a mulch
Grass boarding or mulching
Hugglekulture mound or woodpile
Hedge cuttings, small branches
Shred and compost bin
Uncooked vegetables (including onion, citrus) egg shells
Compost as in 1. Above or Bokashi bins
Uncooked vegetables excluding onions & citrus
Compost bin, Wormery
Trench or sheet composting
Cooked food, including left-overs, meat and fish
Food Composters or digester
Cooked food can be composted in a wormery but is best buried under other material and may smell.
Compost systems (including sheet compost systems) wormery
Contents of Vacuum cleaner, hair including dog hair
So there we have it. The idea was might have been to have a single compost bin to help save the planet and now we have a Domestic Waste Recycling Centre at the bottom of the garden! Depending on your waste and enthusiasm this will include:
- Compost bins and or heaps.
- Cooked food composter
- A wormery (or two if you have dogs)
- A hugelkultur mound for wood and/or a log pile
- A grass boarding area
- Leaf mould bin or bags
- Perennial weed killing area
- Compost trench for runner beans
Now that you have a source of compost it would be a pity not to have an area to use the compost to make Compost tea. It would also be helpful have a space to grow comfrey or nettles as a source of greens for the compost bin, and seeing as you are now growing them, it would be a shame not to include a space for a water butt or comfrey tube to to produce Comfrey or Nettle liquid feed to supplement the compost tea.
At this stage you might consider moving to a house with a larger garden. We will eventually consider all of these methods on the website.
The advic,e often given, is that the compost bin should be kept near the house to avoid frequent trips down the garden path. However if kitchen caddies are used it will not be necessary to visit the bin quite so frequently and it may be located away from the house so that smells and flies will not cause inconvenience if things go wrong. It does need to be accessable from the house (I would suggest by a concrete or slabbed path) and if garden waste is to be composted by a wheelbarrow. In most cases the bin should be placed directly on the ground which should be loosened before being covered by the bin. Fitting a base to the bin will help prevent vermin gaining access to the contents. A concrete standing may recommended for some bins, such as New Zealand bine where they make emptying much easier. A solid base may be recommended for other styles and are certainly advantages when using some of the tumbler bins.
Where possible the composting area should be in the sun or semi-shade so that the heat from the sun can be used to help raise the temperature.
Greens and Browns
Balancing Greens and Browns
“Compost happens” (and if you search the net you can buy the tee shirt) but in actually only happens due to the work of millions of compost creatures from bacteria and fungi to worms. Like all creatures they need food and the right conditions e.g. warmth air and water to and turn the waste organic matter into friable earthy compost. Our compost creatures need a source of nitrogen and carbon.
We divide compostable materials into two main groups Greens and Browns. The Greens are a good source of Nitrogen having a low Carbon:Nitrogen ratio. You may see this in books and leaflets as the C:N ratio. If you are interested in the technical bit Greens have a C:N ratio of less than 30:1 while Browns, beging high in carbon have a C:N ratio of more than 30:1. You do not need to remember this tc produce good compost! There is more about the C:N ratio and the carbon nitrogen content of different materials on the C: N ratio page.
High in nitrogen, they also tend to contain most moisture. Put simply the Greens provide nutrients and moisture for the compost workforce. Examples of greens from the house are vegetable peelings, lettuce leaves, banana skins and coffee grounds. Greens from the garden include vegetable "tops", grass mowings, nettles, comfrey, annual weeds and old flowers. Greens decompose quickly.
High in carbon the Browns decompose more slowly and provides the energy for thesource for the microbes that carryout the composting process.
Browns also provide the means of absorbing excess moisture that would be produced if greens were composted alone. The browns facilitate air-flow within the heap so as to enable the activity of aerobe organisms within the pile. If it is low in browns and it becomes a compacted mess which air cannot penetrate anaerobic micro-organisms take over and produce a smelly mess often found if too much grass is composted. Examples of browns include cardboard and shedded computer paper from the house and, from the garden, potato, pea and bean hulms, stems of brassicas and hedge clippings (preferably shredded)
There are various methods for calculating the Green: Brown ratio but for home composting the current advice is to use about equal amounts of Greens and Browns. For gardeners the Browns, e.g. Tough vegetable or flower stems, old bedding plants, shredded or small pieces of hedge clippings and old straw can be considered as a single group containing material that is slow to rot. However when dealing mainly with garden waste it can be helpful to sub-divided the Greens into two groups so that the quantity of Browns to be added can be adjusted to prevent the Greens becoming wet and smelly. Group one consists of those that rot quickly e.g. grass clippings, comfrey, nettles, young annual weeds and plants, and poultry manure while the second intermediate group which takes a little longer to decompose such as coffee grounds, cut flowers, vegetable leaves and trimmings, rhubarb leaves, soft hedge clippings
Bin Size Matters
We consider different types of compost heap elsewhere but at this stage it is important to make the point that a heap or bin should be at least 1 cubic yard (3’x3’x3’) so that it retain the heat necessary for the composting process to operate effectively. Smaller bins will still work but more slowly. Composting will still occur in smaller piles, it will just take longer to produce a finished product.
If possible the bin or pile should be located in a sunny well-drained area while accepting that in very hot weather it may be necessary to add water keep it from drying out. Some bins such as the Green Johanna like shady areas of the garden.
Many people will purchase their first bin through the scheme operated in conjunction with their local Council without thinking of the volume of waste they produce. This is perfectly acceptable but it is quite interesting to carry out a simple waste audit. If you use a kitchen caddy it is easy to calculate the amount of kitchen waste produced in an average week. If you do not have a caddy use a plastic bucket. Having estimated you wet kitchen waste. It is then easy to calculate the amount of browns required on the basis of either equal ammounts of Greens and Browns or 1 part food waste to 2-3 parts Browns (card and paper waste) depending on the materials you are composting. If you have a garden the quantity of garden waste can also be calculated during the growing /harvesting season using the bucket method with one bucket for green and one for browns. From these calculations you can estimate the size of compost bin or heap required. Alternatively you can be like the rest of us and keep buying/making bins as the compost bug takes hold.
Cool or Hot Composting
Composting is cool or at least the method of composting used by most people is known as Cool Composting because the heap does not get, or remain, at the high temperatures that can be achieved with the more labour intensive Hot systems.
Hot or cold
We look at different composting systems and containers later but whether you opt for a pile, heap, wooden, brick or plastic bin you will as with much of life you will need to start at the bottom and work your way up.
Starting at the Bottom
It is generally accepted that we should try to provide a good airflow to ensure aerobic composting (this may need to be reduced in the winter if the air temperature drops) and this can be achieved by standing the pile or bin on a pallet base, however this may restrict access by worms if there is a gap of 6” across the whole of the base so you might consider filling parts of the pallet with earth. Adding sticks to the bottom 6” of a bin placed directly on the soil is also suggested as a way of increasing airflow but remember that this may cause problems if they are to large and you intend to empty the bin using a shade and the hatch provided in many plastic bins as the wood may make removal of the finished compost difficult. If this bothers you use any coarse “browns” such as straw, corrugated cardboard (exclellent as it traps the air), scrunched up cardboard boxes as an alternative to twigs directly onto the soil.or be added to them twigs This problem can be overcome if the bin does not have a base by lifting the whole of the bin off the pile of compost to harvest the compost (and if you are keen to aerate it at intervals).
It helps if the material being put in the bin is layered using alternative layers of browns and greens. This is not so important with modern cold composting systems but even if you are just going to chuck waste in as it arises it is good to start with a layer of browns. Once you get going you can make adjustments by eye i.e. if it is too dry add greens if too wet add browns
Next add a layer of Greens. Continue as adding material as waste becomes available it is not necessary to add separate layers of greens and browns (aerating the heap or bin will mix them anyway so if you find adding a mix of greens and browns as they become available do so) but what ever you do you need to keep the ratio of greens and browns right otherwise the material will become wet, black and smelly, of just sit in a dry plie doing nothing other than proviing a dry home to rats and mice. You can keep the number of flies and other insects to a minimum by always covering the layer of greens with browns until the bin is full or the compost in the bottom of the bin is ready.
If you are happy to wait a year or 18 months compost will indeed just happen in the bottom of the pile. If you need a quicker turn round because of lack of space, more time to manage the system or a modern bin which provides some form of insulation and aeration you could have compost in a couple of months. Aerating the bin or heap will speed the process and depending on your choice of bin this can be down manually by forking, manually but with less effort using an aerator in a modern bin or by tumbling or rotating the bin.
If you have a wooden bin with a removable front of a plastic bin with a large opening at the base e.g Komp 250 or Hotbin it is easy to inspect and remove the finished compost through the hatch. If you bin only has a small hatch and no base it may be easier to lift the bin off the compost leaving a exposing the compost. The top layers will not have composted and should be returned to the bin if the material at the bottom of the pile has composted use it on the garden.
Ensure that the material returned to the bin is mixed well (aerated) and add water if it was dry Some composters use this process of removing the bin, mixing the compost and returning it to the bin at regular intervals to aerate the contents and speed up the composting process.
The Hot Heap
Many of us older composters may remember steaming compost heaps in the gardens of the "big house" or may have seen them on visits to National Trust properties. We can use Hot syatems at home but they require more work and operate best if a batch of three bins are used. We will look at these systems in detail elsewhere.
To start a hot heap you will need to collect enough material to fill your compost bin at one go. This will require somewhere to store the material before it is added to the compost bin In order to increase aeration it the tougher items such as stems should be shredded or chopped up using a spade, shears or secateurs. The green and brown ingredients should be mixed, either before or as they are added, and watered. The heap will heat up within a few days and then after a week or two start to cool down. You can measure the temperature with a thermometer of leave a fork in the heap for a couple of hours. If when you remove the fork you can hold the prongs it is time to turn the heap. From which you can conclude that if it burns your hands everything is fine!
Once cooled the contents of the heap are normally turned over into a second putting the material that was on the outside trying in the centre. Water is added if the contents are dry, and more browns if it is wet. The aerated bugs in the heap should burst into life and the heap will heat up again. Repeat this turning until there is little or no heating of the pile. Hot Composting can be achieved with a single heap but mixing the content is more difficult. However turning the heap is the key to quick composting.
We will consider some of thetraditional methods of composting before looking at the range of modern bins available.
Open Air Composting
Open air composting is probally the simplest method of composting in that all you do is make small piles of compostable waste in conventient places round the garden. It will take some time to breakdown, considerably longer than in a compost bin and does not look every tidy. Food waste should be avoided as this would attract vermin and smell(?). However manure can be added to provide a nitrogen boost.
Even if you have a large garden with lots of unvisited areas I would not recommend this approach. Ian Walls in Creating Your Garden (Collins 1967) wrote "Very few gardeners make their compost correctly as unfortunately, the term `compost heap` generally means a glorified dump where herbage is stacked on herbage, excluding air and preventing any heating." He continued that disease, pests and diseases present in the original material, survived the so called composting process and would be spread when the rotted material was used. It also looks a mess!.
Sheet composting is a technique where organic material is spread over an area of the garden and composted in situ. It builds up organic soil content quickly and involves less work than using a heap or bin. It offers the advantage to gardeners with large gardens in that a large area can be composted with minimum effort. Sheet composting provide a cheap way of filling a raised bed rather than using purchased commercial compost A further advantage is that if the soil conditions are right i.e. airy, moist, , warm and has high levels of nutrients it will produce compost fairly quickly provided the organic materials have a the correct carbon, nitrogen ratio. If the C/N ratio has too much carbon the soil will be depleted of nutrients during the initial stages of decay while the surplus carbon has been consumed. This is a common problem when woody material is spread on the garden.
The autumn is a good time to start sheet composting. To prepare the area remove any pernicious or persistent weeds as sheet composting may not smother these weeds. If the area consist of grass mowing or scalping the grass down to the lowest possible level over the area to be composted. It is suggested that the composted area does not exceed a width of 3-4 foot as this will enable the center of the bed to be reached from either side during composting.
It helps to loosen the soil underneath the proposed bed with using a fork to improve drainage. It helps to spread a 2 to 4-inches of organic material over the surface and dig, hoe or rotavate into the soil. Cover with 4-6 overlapping layers of newspaper or cardboard (carbon material that smothers the grass. Wet the newspaper or cardboard thoroughly.
Cover the papers with a one-inch layer of a nitrogen source materials e.g. green garden waste (including fresh green annual weeds having removed any seed heads, kitchen scraps, comfrey or nettle leaves, manure or a mix of any of these.
Cover with another layer of carbon material e.g. cardboard, leaves, shredded paper, straw. Continue to adding alternating layers of nitrogen and carbon materials until a height of between 18 inches to three feet is reached. As the material decomposes additional layers should be added always ending with a carbon layer.
Lasagne composting is no-dig, no-till method of organic gardening utilising sheet composting. It is so called due to the layered appearance of the composting process which resembles a Lasagne. It does not imply that it is edible.
As described above a layer of wet corrugated cardboard or three layers of newspaper is laid directly on top of the soil, or grass. Alternate layers of “browns” and “greens” are added to a height of about two feet. The brown layers should be twice as deep as the green.
This can make an excellent way of filling a raised bed.
Grass boarding is a type of sheet composting that is very useful if you have a large lawn or grassed area such as the paths and car park on an allotment site.
The technique originated at the Centre for AlternativeTechnology, which is well worth a visit. All that is required in addition to the grass mowings is cardboard or paper. Corrugated cardboard is very effective but discarded paper towels from the office can also be used, as can any of the usual paper materials normally added to the compost bin.
The technique can be used on open ground to form a heap, enclosed within a wooden frame to keep it tidy or for smaller quanties undertaken in a dedicated compost bin. All that is reuired is alternate layers of cardboard, or paper, and grass. Spread the grass about an inch or two deep and then place a layer of carboard on the grass. Do not press it down or compress it as you do not want it squashed as this will result in anaerobic fermentation which will result in a smelly mess.
If a compost bin is used the paper should be torn up and crumpled to assist with the aeration of the material but large sheets of cardboard can be used on open heaps
Grass, Card and Soil Sandwich
A variation on grass boarding involves the addition of soil to the heap as a means of introducing additional microorganisms to the composting processes. The heap is started in the same way as conventional grass boarding by loosening the soil and applying a layer of cardboard or paper which is covered by a 20cm (8”) layer of fresh grass clippings. A 3cm (1”) layer of soil are added to the grass followed by alternate layers of cardboard/paper, grass and soil until the heap reaches the desired height. The heap may be covered to keep it dry during wet periods but may need watering to provide moisture during dry hot spells. I would suggest starting a new heap each grass cutting seasons as heap prepared during one summer should be ready for use ready for the start of the next.
Mulching with Grass Clippings
Mulching is a simple alternative to composting when faced with large quantities of grass cuttings and offers a good way of controlling weeds, reducing the need to water and to provide some nutrients to the soil. Add only thin layers of grass (maximum of about an inch) of clippings at a time.
Pit and Trench Composting
In-ground trench or pit composting provides a simple way for composting fruit and vegetable waste including uncooked kitchen scraps.
Pit composting is suitable for an area where there is limited space either because the garden is small or is permanently planted areas such as perenial flower beds.
Trench composting is usually used in the vegetable garden so that composting can be started in the late summer or autumn with the trench being filled and ready for spring planting of runner beans, french beans or peas.
Trench composting can be started earlier, if space is available on the plot, so that chopped brassicas stalks can be included as this offers an easy method of composting the stems which may be slow to compost in a conventional compost bin.
A similar method where circular pits are dug, rather than a trench, can be used for courgettes and pumpkins.
The trench is often dug for convenience about a spade width and depth the length of the required bean row, which might be across the width of an allotment plot. It is worth checking the recommended planting distance for the beans as; if a double row is required the trench will need to be wider.
Place the soil along the side on the trench so that it may be used to cover the composting material as it is placed in the trench. Start added the waste at one end of the trench covering it with the soil as it is added. Some people dig a deeper trench so that a second layer of waste can be added but this will depend on the quantities of waste available and the number of rows of beans to be grown. When the waste has been covered the soil is likely to have made a small mound along the length of the trench but this will settle by the time of planting. I would suggest marking the trench with small sticks so the it can found in the spring when you need to plant in it.
Some gardeners use trench composting as part of a composting rotational system where the trench is moved across the garden each year.More information can be found at
This Permaculture technique technique involves the creation of a combined raised bed and compost heap which is said to remain fertile for up to 6 years. I do not have experience of how effective the system is but are currently building a Mound at the Sibston Composting Demonstration Site.
The system was invented in 1979 by Hans Beba and Herman Andra although composting and growing in mounds is said to have been used in Eastern Europe for hundreds of years. I have included it here as a means of composting woody material including quite thick logs and tree stumps. This is not intended to replace the insect and hedgehog friendly wood pile in the garden but it does provide an interesting additional composting tool.
The base material used in the bottom of the trench, or directly on the soil if a trench is not being dug, is wood of varying sizes. This can include rotting logs, sticks, branches and twigs. The mound can also be built round tree stumps and provides a means of composting them.
As the technique involves building a "raised bed" rather than a traditional compost heap the site of the mound does not need to be hidden at the bottom of the garden but can be in view. This makes it easier to choose a spot where plants can be grown on the mound once it is established.
Although described as a "mound" it usually starts with a trench with a raised mound structure being built by the addition of the layers of compostable material. As with a normal trench composting the system it is designed to be started in the autumn so that the heap will be ready for sowing for new growing season in the spring.
While digging a trench is desirable, as it helps keep the mound tidy and retains moisture, it is not necessary; the mound can be built straight on top of the soil or even on concrete. Where the mound is to be built directly on the soil a number of sources suggest mowing or strimming any grass and then covering the ground with damp cardboard.
If the mound is to be built in trench on a grassed area the grass should be removed carefully as turves, which are set aside for use during the next stage of construction.
The soil dug from the trench is kept for use as the top layer of the completed mound. If the mound is being made in a previously dug part of the garden it will be necessary to obtain turves from elsewhere or to miss the turf layer.
The trench is dug, normally in a north south direction about 1.5 meters wide and 12" deep. It can be as long the compostable material available permits. The mound will shrink so build it higher than the final height that you would like the bed to be.
Once the trench is dug a border of logs, boards or stones may be built round it to frame the bed and keep it tidy, alternatively a more natural mound may be built without a frame.
Logs, branches and other woody matter which decomposes slowly are placed in the bottom of the trench. The larger items are used first with the smaller branches, twigs leaves wood chip and other compostable materials added over the top of the woody layer and to fill the gaps between the larger pieces of wood. If the mound is being built in the New Year the discarded Christmas tree can be included in this layer. It helps if the larger stumps and logs are already rotting.
Because of the inclusion of the wood the mound will initially be low in nitrogen so it is important to include nitrogen rich materials such as manure, kitchen waste or grass to help fill the gaps between logs and in subsequent layers. The material should be watered well.
If turves have been saved they should be placed upside down (with the soil/roots up) over the woody material forming a domed cover. Water the turves and each subsequent layer as it is added.
The turves are in turn covered with a about an 8”- 12" thick layer of garden waste, leaves and the usual compostable materials. As with the woody layer use the larger items first. This in turn is covered by a 4 - 6” layer of semi-mature compost or manure. These layers can be repeated until the desired height is reached (remember the mound may shrink by a half during the first year).
The soil removed when digging the trench is then used as a final layer to cover the pile. If the mound is built correctly the heat released by the decomposition will warm the soil helping to extend the growing season
Turf is usually composted separately from the compost heap using a turf (or sod) pile. A stack of turves will rot down to produce a really good material that can be used in making homemade potting composts and in the garden.
The technique is simple. First lift the turves and place a layer grass side down on the soil. Put the next layer of turf on top of the first grass side up. Then continue adding layers of turves, alternate ways up i.e. the next, grass side down followed by grass side up. Continue until all the turves have been stacked in the pile. Cover the heap with black plastic secured in place so that it does not get blown over the garden. Leave the heap for at least two or three years until completely composted