Clear Mountain Garden Treasures

Clear Mountain Garden TreasuresRecycled Garden

Recycled Garden

Good soil is key to a good harvest

Composting is nature's way of recycling. In a forest, detritus from plants and animals, fall to the floor and is decomposed. The top most layer is made up of newly fallen material.

Working downwards, successive layers are progressively more decomposed. Plant roots, micorhizal fungi penetrate the bottom layers to extract nutrients released by the decomposition process. This whole structure forms the living soil.

Composting basics
What can be composted
Compost bins
Using compost
Health hazard

 Composting basics

Green garden waste.

Brown garden waste.

The home gardener can emulate the natural composting process by creating a compost heap. Start the heap by placing coarse matter, such as twigs, at the bottom. This is to provide drainage and some aeration.

Then build the heap with alternate layers of green and brown matter. Green plant matter, such as grass clippings and kitchen waste, is rich in nitrogen Brown matter, such as saw dust and and shreaded paper, is rich in carbon. The ratio of green to brown matter should be around 2:1 to 3:1.

If too much green matter is used, the resulting compost will be slimy and smelly. If too much brown matter is used, the decomposition will be very slow.

Both types of plant matter should be chopped up and roughly be of uniform size. Smaller pieces break down faster, so the total time taken for the whole heap to decompose is dependent on the size of the larger pieces.


Composting process

Turns waste to rich compost.

The decomposition is performed by an army of microbes (bacteria and fungi) and invertebrates. The heap should be placed on top of soil. Microbes will migrate up from the soil to colonise the heap, starting the decomposition process.

The microbes need both air and water. When layering the heap, insert large branches diagonally into the heap. When the heap is built up, carefully remove these branches to create air tubes within the heap. This help the heap breathe and promotes oxygen breathing microbes. Poorly aerated heaps encourage anaerobic microbes and will turn sour. Turning the heap will also help aerate it.

Water the heap as it is being built. The amount of water used depends on the type of material, but in general, the compost heap should be like a damp spongue. Insufficient water will slow down and even stop the decomposition process. Too much water will compact the heap, blocking air and turn the heap sour.

At the start of the decomposition process, nitrogen is required to perform the initial break down. To aid this, add blood and bone to the heap as it is being built. As the break down progresses, it will release nutrients, which includes nitrogen, to facilitate further breakdown. The break down process also creates acids, and to keep the heap sweet, add hydrated lime. Hydrated lime is quick acting and is very soluble. Ordinary agricultural lime can also be used, but it is not as effective as hydrated lime.

The first stage of decomposition is usually pretty quick, as microbes use up easily available food such as sugars and starches. This quick action usually heats up the compost, to around 60 degrees. The heat will sterilise weed seeds and kill pathogenic microbes. Once the initial food has been depleted, the process goes into another phase where different microbes break down harder material, such as cellulose. The heap then cools down.

Compost is ready when it is of a uniform colour and it is no longer possible to identify the individual particles.

 What can be composted

Convert kitchen waste to compost.

Green kitchen waste can and should be composted. Composting your kitchen waste reduces your household rubbish, and more importantly, reduces the amount that goes into landfills. Examples of kitchen waste are tea bags, vegetable scraps, leftovers, fruit peel, apple cores, crushed egg shells and coffee grinds. Hard vegetables such as cabbage cores and corn cobs should be chopped up before composting. It is best to keep a separate bin for kitchen waste that can be composted. This can be emptied into the heap once every few days.

Do not compost cooking oil or waste that contains a lot of oil. Leftovers that have a high salt content (eg. salty chips) should also be avoided. Meat and dairy products can be composted but it best to avoid them as they attract mice and flies.

Pumpkin can invade the compost heap.

Vegetables such as potatoes and pumpkin seeds are also best to be avoided. It seems like the heap temperature is not high enough to kill these and if used, they may then germinate when the compost is used. They may even germinate in the heap itself and colonise it!

Garden waste should also be composted. Lawn clippings can be used as is, although it is best to avoid a thick layer of clippings. Build a thin layer, then alternate with brown matter. Weeds should be left to wilt and die before composting.

Autumn leaves make excellent compost or
leaf mould.

Avoid weeds that have gone to seed. Although the heat in the heap will kill most seeds, it is entirely possible that weed seeds may survive. Avoid composting weeds with underground storage organs, such as ones with bulbs (eg. Oxalis). These underground parts may not be completely destroyed by the composting process.

Small branches can be cut to 10cm lenghts and used as is. Larger branches are best processed through a garden shreader. Treat branches as brown matter.

Autumn leaves from deciduous trees make excellet compost, although they can be a bit low to break down. The alternative is to heap the leaves separately. These will gradually decompost to make leaf-mould, excellent for adding to potting and seedling mixes.

DIY waste such as saw dust and wood shavings can also be used except if the wood has been treated. Wood is brown matter.

 Compost bins

Compost can be made in a variety of ways. The simplest is to simply build a compost heap by stacking layers of material. This approach works, but can be messy and takes up more room.

A better approach is to use a compost bin. A simple rectangular bin can be made up of 4 posts in each corner. Wood palings are then nailed horizontally into the posts to form a rectangle. Leave a 5 cm gap between the palings for ventilation. The size of the bin should be around 1 cubic metre.

Easy measurement  If the posts are spaced 1m apart, then building the compost bin to a height of 1m will give it a 1 cubic metre volume.

When building bins, it is better to build 3 bins. Add waste matter into the first bin. The second bin stores compost that is decomposing, and the third bin stores compost that is ready to be used. A lid will stop excessive water from heavy rainfalls to flood the compost.

A lid will stop excessive rains from flooding the compost heap.

Done this way, a compost heap in the summer typically takes around one season to decompose. Heaps started in the autumn typically will be ready in the spring.

An alternative is to use bins purchsed from garden centres or DIY centres. These tend to be made of heavy duty plastic with a lid and an open bottom. Some models have adequate ventilation holes but most will need extra holes drilled. It can be difficult to turn compost in these bins due to their small size. One way to turn the compost is to tip the contents of one bin into another.


Compost that has had plenty of ventilation will decompose faster. To really speed up the decomopsition, a tumbler can be used. These can be either manual or powered by a motor. The tumbling action turns and aerates the compost. Powered tumblers constantly aerates the compost, resulting in quick decoposition. Often these can create compost in a matter of days.


A worm farm can provide a viable alternative to composting, but it is has limited capacity. Worm farms are also made up of layers. Kitchen and garden waste goes on to the top layer. Worms feed on this layer, converting the waste into work castings.

Once a layer is full, another is added on top. The worms will then migrate to the top later, leaving the bottom layer of castings to decompose. Worm farms produce a liquid (worm tea, or should this be called worm pee?) that needs to be diluted and can be fed to plants as a liquid fertiliser. This liquid is trapped in a reservoir at the bottom and can be drained off and used as required. Warning Worm tea is quite strong can should never be used neat. Certain plants are sensitive to fertilizer and worm tea may cause damage.

Material has to be added gradually to a worm farm. Avoid large build up of material as it will turn sour before the worms have a chance to eat it. Also, avoid times of famine for the worms. Make sure the worms always have something to eat. Keep some spare feed for when there is no kitchen or garden waste. Avoid very hard or large pieces, as the worms may not be able to eat these.

Tiger worms as best of use in farms. Ordinary earth worms burrow into soil and do not like to be disturbed. Tiger worms are more suited to the dynamic nature of a farm.

It is best to place farms in cool dark spot. Do not allow worm farms to freeze and avoid the scorching sun.

Compost produced form worm farms come mainly from worm castings. It has a fine texture, suitable for inclusion into potting mixes.

 Using compost

Compost is mainly used to augment soils, to improve their structure and to provide some nutrients. The actual amount of nutrients is relatively small, and compost is mainly used as a bulk organic fertiliser. Compost in soil acts like a spongue, sucking up excess water and releasing it to plant roots. Clay soils hold more water than sandy soils, but with the addition on compost, even sandy soils will hold more water than pure clay!

Compost is alive, meaning, it still has microbes and other invertebrates from the decomposition stage. It attracts earthworms to the soil, and the worms, in turn, improves the soil structure. The microbes also compete against pathogenic microbes, restoring a balance to the soil.

Compost can be used sparingly as a mulch. Avoid large build up around tree trunks. Compost mulch breaks down quickly and is more suited for the vegetable garden. If the compost has a mix of fine and coarser material, it can be sifted and the coarse bits as mulch.

Compost can be sparingly added to potting mixes.

 Health hazard

Wear a mask.

Lastly, compost may harbour bacteria and fungi that cause human diseases, especially to kids, the elderly and imune compomised individuals. When handling compost, be careful not to inhale the dust. Use a dust mask if the compost is unusually dry and dusty, or especially if you are imune compromised. Wash hands before eating or handling food.







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