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Choosing Your Compost Bin (which is better for you) - By Angus Stewart 

What is composting?

Composting is the process of decomposing materials that were once part of a living organisms. It really is possible to come up with a composting system for any size garden from a balcony to a farm. Let us look at how to get yourself up and running from scratch.

Choosing a composting system

The choice of what composting system to install will depend on a number of factors such as space, the amount and type of organic material you want to compost, pest problems such as rats and mice, cost of the system, and the time a gardener has to make it work.

If you are a total beginner to composting then we suggest you start with a system that is based on 'cold' composting, as opposed to 'hot' composting, so let us explore the difference between them.

Cold versus hot composting

To experienced gardeners composting generally conjures images of hot steamy piles that smell strongly of ammonia. This is a classical 'hot' compost heap. Hot composting occurs when conditions are right for beneficial oxygen-loving micro-organisms (known as thermophilic or heat loving microbes) to build up rapidly inside the heap creating temperatures up to 80 degrees C. If the heap does get that hot for at least several days, it will be sufficient to kill virtually any weed or plant disease present.

'Hot' composting is obviously a wonderful idea as it allows you to decompose virtually any organic material. Unfortunately, it is often not practical to get it hot enough in the average suburban backyard to be fully effective. The major problem is that a critical mass of at least half a cubic metre is generally required to achieve high enough temperatures to kill any weeds or plant pathogens in the pile. The heap also needs to be aerated every few days which may be too big an ask for time poor suburban gardeners. If this sounds like you then there are composting alternatives that take longer but need much less maintenance.

'Cold' composting on the other hand is not as quick but is a much more practical option for small gardens. It is the process whereby a variety of micro-organisms gradually break down the layer of organic matter on the soil surface in a natural forest ecosystem. Small amounts of organic waste will undergo the same process in a garden situation and will be helped along by earthworms that are attracted to and feed on materials that have sufficient nutritional value to sustain them. The higher the nutritional content the quicker breakdown will occur such that kitchen scraps tend to be gone in a matter of weeks while woodier materials such as dead leaves and bark may take many months or even years if they are left to their own devices. The trick is to mix higher nutrient materials with the lower ones to speed up the cold composting process. Another advantage of cold composting is that it can be done in a dark, shady corner of the garden that is not much good for other purposes. A hot compost heap ideally needs to be in a sunny position to generate the heat needed to kill weeds and diseases.

While cold composting is probably a more practical option for today's gardener it needs to be understood that it takes a lot longer than a well maintained 'hot' heap. Diseased plant material and persistent perennial weeds such as grasses with runners (e.g. kikuyu and couch) or bulbous plants such as onion weed, and oxalis will only be destroyed in a sufficiently hot compost heap. Meat scraps and bones should also be avoided in cold heaps as they can stink and attract vermin more so than other organic wastes. For all these problem materials either use hot compost heaps or simply deposit it in a green waste bin which will result in it being composted at a suitable facility. Let us assume that you decide to start with a 'cold' composting system here are some practical tips to get you going.

Small households with mainly kitchen scraps to compost.

One of the best options is a worm farm for this sort of situation. Tumbleweed makes a range of worm farms that are suited to various household situations.

• The simplest option is an in-ground worm farm called the Worm Buffet which is partly buried, and you simply add kitchen scraps regularly and the worms can travel in and out of the worm farm distributing the composted material as they go meaning that you rarely if ever need to empty the Worm Buffet. The Pet Poo Worm Farm is a much larger unit that is designed to take not only pet poo, but also all your kitchen scraps as well.
• Indoor worm farming for those in home units or apartments can be done with the Tumbleweed Cube that can be tucked away in a space like a laundry or kitchen corner. It is a small worm farm designed for a one- or two-person household.
• Above ground worm farms of various sizes are available for larger households and especially those with outdoor garden areas. The benefit of above ground worm farms (which also includes the previously mentioned Worm Buffet is that you can easily harvest the liquid the worms produce which is one of the best organic liquid fertilisers you can give your plants, and particularly edible gardens. For smaller households the Can-O-Worms is a good size, while for larger amounts the Worm Café is the next step up in size, with the Worm Factory slightly bigger again.

Larger households with kitchen scraps and organics such as lawn clippings and autumn leaves etc

For those on larger blocks of land with bigger gardens that generate organics beyond kitchen scraps we recommend one or more of the following compost bins:

• Gedye Bins 220 or 400 litre capacity, these very solid bins have a snap-on lid that helps exclude vermin from getting in. Put some rodent proof mesh underneath and you will eliminate these troublesome and ubiquitous pests from your composting system. Gedye bins are perfect for cold composting as you can also add earthworms that will help speed up the process.
• Tumbleweed Compost Tumblers 110 , 170 and 220 litre bins are also great for excluding rodents, while the tumbling action makes it easy to bury newly added scraps and will help speed up the process if you give them a turn every time you make a new deposit.
• Tumbleweed Flat Pack Compost Bins 200 and 240 litre. These are the cheapest options to get you started in composting, with the ability to dismantle them making them easy to transport and store. They are well suited to composting yard materials such as fallen leaves, twigs and lawn clippings that are not so attractive to rodents as kitchen scraps. A combination of a flat pack bin with an above ground worm farm for kitchen scraps is a good combination.

Now that you have decided on the bin that is right for the size of your garden and the type of waste you are generating, stay tuned for our next blog post on how to set them up and maintain them.

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