The ‘Cool Compost Bin’ …..
…….. is a traditional method of composting that uses a closed large tub to contain waste. These are usually made from recycled plastic and can be purchased from a local plant nursery or retail hardware outlet. Well managed, the cool compost bin offers a rich source of organic matter. The container has a neatly fitted lid that is removed to deposit waste material and is open at the base, siting directly on the ground where it drains and easily accessible to worms and micro-organisms living in the soil.
People often talk about problems with this type of bin, especially when waste is soggy and becomes sour, a problem that is best avoided through good management but can also be easily solved. The closed bin is a good performer in urban areas as the lid ensures that flies and birds do not have ready access to the waste.
Because the bins are mobile they are perfect for people who are renting. When you move house the bin can move with you – scooped up into buckets – so can your compost.
One of the secrets to success for the cool compost bin is patience. The other secret is introducing a variety of material and layering the waste to balance the mix. This technique is excellent for the busy person who is time poor and has an erratic interest in gardening. The mix can be quietly working away decomposing while you’re going about life. The cool bin will offer the busy ‘urbanista’ a rich source of humus when the weather is perfect and they have a window of opportunity to try their hand at gardening.
Step 1: Place your open bottomed bin in a convenient and strategic spot. Consider the route you travel every day; as you walk to the gate, or are leaving via the tram, train or car – near your rubbish bin, collecting the mail or hanging out the washing. If you are making a regular journey past the compost bin you are more likely to deposit waste or ‘give the mix a stir’. I often place a bin at the base of a tree, the goodies that drain into the ground are beneficial to the tree and the worm activity around the tree is a bonus. I also think about where I might be going to develop a new garden bed and make the compost in that spot. When it ‘s ready it’s just a matter of slipping of the skin, scooping off the top third of the compost material and spreading the remaining contents over the garden – easy.
Don’t think of the bin as an unsightly feature to hide away, place it somewhere that is pleasant and easy to visit. Design your garden around the bins, plant nasturtiums and herbs or plants that will benefit from the draining nutrients.
Step 2: Once you have found the perfect spot begin by putting cardboard or wads of paper down, placing the bin over the top. Then begin to fill the bin by building layers of waste. Kitchen scraps, straw, shredded paper, pizza boxes, an occasional handful of pellitized manure, grass clippings, chopped up green garden waste. Never put too much of one item in at the same time, a variety of materials and layering the elements is the key to success. Stockpile a range of waste material close by so you can throw a material into the mix.
Always place a layer of straw or dry leaves mixed with shredded newspaper over the top of the sloppy waste, then a handful of manure over the top (this can be compressed or pellet type garden manure that is purchased in a bag from the local garden supply – try and buy a certified organic mix). Lawn clippings are excellent, be careful to not add a thick layer, they can very quickly become soggy or dry if they overheat. Occasionally the mix will need some extra moisture, sprinkle with the hose or add a few buckets of water and ‘tease’ the mix with the tines of a garden fork.
If you want to vermin proof the bin you should do this at the beginning. Before you start place a piece of chicken wire or similar mesh down before you put the cardboard down. This is not an absolute barrier to keep rats and mice out but it will discourage them.
Layering of material is important as it evenly distributes wet and dry ingredients and will prevent the heap from souring. Don’t add material that is chunky, try and chop things up a bit, it helps with the process of decomposition and will speed your compost making.
Occasionally you will need to stir the mix. Do this with the garden fork by placing the tines down into the compost and gently lifting the waste. This will aerate the material and accelerate decomposition. Do not use a spade, the blade slices through your worms – the fork is kind and teases and lifts the mix without harming your little urban helpers. You could purchase a compost twirler. This tool twists down into the heap and lifts material, distributing air into the decomposing matter. Either way a good agitate and the mix will be revitalized.
Look for dry spots when you’re mixing – a quick hose or bucket of water over the dry area will help reactivate the compost. If the mix is soggy or wet then add some straw, shredded newspaper or leaves and mix this through, sprinkle with a little coffee grinds and top off with straw. It you are adding moisture to your compost add some liquid seaweed fertiliser to the bucket, this tonic will also give a sluggish compost heap a boost.
There are two enemies in compost making – when the mix is to wet – or – when the mix is to dry! By trial and error you will learn how to manage this balance to make sure your compost keeps progressing along.
Through this process you will eventually build layer upon layer of goodness. The bottom of the bin will compress and be active with worms while the top might still be quite ‘green’ and loose with new material. I always try and have the mix capped with some straw, it helps control any smells or compost flies and keep things ‘sweet’ and moist. Push the straw aside when adding new material and reuse the capping straw at the top again and again.
Step 3: Time and patience is required to make cool compost. I judge that it takes between 4 to 6 months to reap the rewards. When the contents of your bin are reaching the top of the container leave it a while, check for dampness, give an occasional stir with the garden fork and allow the material to settle. You will be surprised by the number of worms that will make their way up and through the decomposing waste. This is what you are aiming for, natural decomposition together with worm activity that will transform sloppy waste into rich humus.
When the mix has subsided a little you can add extra layers – this is especially good for people who don’t have much time. The bin will look after itself between your bursts of interest.
Step 4: I judge if a bin is ready by gently lifting the plastic skin of the whole bin and slipping it up to reveal the bottom. It is ready when there is a healthy amount of black moist humus at the bottom. You will see multiple worms scurrying to find a dark hiding place when you do this. You can put a garden fork into this bottom layer to ‘investigate’ the progress of decomposing material.
When there is adequate humus remove the plastic container and transfer the cyclinder to a new spot. Prepare the bin as you did in Step 2 with cardboard or shredded newspaper at the bottom and place a little dampened straw over the paper. Using a garden fork scoop the top third of the mix into the bottom of the new bin. This is your compost starter. I compare this to yeast in bread. The starter will make an excellent base for your new bin and will mean you may not have to wait so long to harvest the next round of contents. Always make sure you also transfer some of the worms, they are urban livestock, your little garden workers.
The new compost is ready to spread on your garden. I find I get the most from my compost when I add it to an area after I have forked over the soil. I make sure the ground is moist before I top dress with the compost and I often ‘cap’ the compost lightly with some extra damp straw. This means any worms that have been moved from the bin have an immediate source of food and continue their good work in your garden. If the worms have no source of food they move elsewhere or simply die through lack of food.
A few extra hints
Adding Coffee Grinds: I find that used coffee grinds are an excellent material to sprinkle over the top of the wet waste when you deposit it in the bin. Worms love the gritty nature of the used coffee and it helps to stabilize the mix and controls compost flies. I collect coffee grinds from a local cafe and stockpile it in a bucket for quick easy access.
Have more than one bin: I always try and have a number of active bins on the ‘go’. This allows me to alternate where I dispose my waste and allows time for the process of decomposition to take place between deposits. It also avoids souring inside the bin with an over supply of wet waste. Having a number of bins allows me to rest a bin for a while – I usually allow 4 to 6 weeks from my last deposit before I use the waste.
Do Not Add Citrus or Onions: This is a rule that can be bent. I believe it depends on the quantity of citrus and onions you are adding. I do not eliminate these from my cool compost but would never add them to my worm farm (refer the the blog posted 23 August 2015). If you use a lot of citrus then I would be cautious and carefully manage the amount you are adding. You might like to try having a citrus only deposit spot and see what happens. Pineapple is also a questionable fruit.
Egg Shells: I add these to the compost but crush them well. I collect the shells, wash them and place them together in a baking tray. The shells then go in and out of the oven when I am baking – to absorb the ‘end heat’ – this makes the shells very brittle. When I have collected enough I grind them with a mortar and pestle and add them to the worm farm, use them as a snail barrier or sprinkle them amongst seed in the chicken house for grit. Ground eggshells are also good sprinkled around seedlings to protect young plants from snail and slug activity – the pests do not like the very sharp nature of the crushed shells.
Animal Waste: People have often asked me what about my dogs droppings. I have a small dog and she has small droppings but I don’t add them to the compost. I use them as a deterrent for foxes and scatter the dog waste along the fence line near the chicken house. However I have read that pet waste can be used in compost but not on plants and produce that you are going to consume. Save this ‘type of compost’ for the decorative parts of the garden and have a special small spot to deposit the material separate from the goodies that will go on your edibles.