Composting

Buying a compost bin

We are currently offering Bristol residents subsidised compost bins and have the following bins available to buy:

• 220 litre bin (90cm high, 74cm diameter) for £12.
• 330 litre bin (100cm high, 80cm diameter) for £15.

These prices include delivery and will be delivered within 14 working days of placing your order.

Please note: Product colour may vary.

You can buy your compost bin in the following ways:

• Buy online.
• Contact our Customer Services Centre on 0117 922 2100.

What's in?

Browns are dry, fibrous materials which are high in carbon. These include:

• Cardboard tubes
• Egg boxes
• Straw and hay
• Woody prunings (shredded / chopped)
• Old perennial plants

Greens are soft, sappy materials with a high nitrogen and water content. They include:

• Fruit and vegetable peelings
• Grass clippings
• Green prunings
• Annual plants
• Weeds
• Flowers
• Young hedge clippings
• Fruit / vegetable crop remains

You will get the best results by using a mixture of half browns and half greens. Remember that worms don’t have teeth, so to get good compost as quickly as possible, it is best to chop your material up into little pieces. 

The general rule is that anything that was once alive can be composted.

What's out?

There are some things that are best not put in the bin, either because they will not rot down properly, or because they will create smells and attract pests:

• Meat or fish.
• Dairy products.
• Cooked food.
• Cat and dog waste.
• Disposable nappies.
• Biscuits and bread.
• Diseased plants.
• Plastic, glass and metal.
• Coal ash.
• Japanese knotweed.

If you are still unsure whether or not something is suitable for your compost bin, Have a look at our composting frequently asked questions

Getting started

Home composting is an inexpensive, natural process that transforms your food and garden waste into a valuable resource for your garden.

Finished compost can be used on flowerbeds, vegetable plots, and for mixing into planters. It can really make your garden and houseplants bloom.

To start composting you need a space in your garden to store your compost bin. Alternatively you can build your own compost bin. Building a box using wooden planks is common practice (make sure it has a lid or cover as well), and insulating it with cardboard or straw helps the composting process.

• Place your bin somewhere level and well drained, on soil or grass. This is so that excess liquid can drain out and worms can get in to start breaking down the waste.

• Ideally, you should place it in a partially sunny spot, but don’t worry if you have to put it in the shade; your waste will still break down, but at a slower rate.

• If you cannot place your bin on soil and you have to put it on a concrete or paved surface, add some healthy soil, compost or manure to introduce some micro-organisms and get the composting process started.

• Make sure you can access your bin easily, and leave enough room to mix the waste and get the finished compost out.  If you find it difficult to stir, add scrunched up paper or small cardboard items. This will ensure that you have air pockets in the bin.

• Ensure your compost bin contains a balanced mix of materials and the right amount of moisture and air (see below). 

• Keep adding garden and kitchen waste to the top; the process begins in the middle and over time you'll have finished compost at the bottom of your compost bin ready for use in your garden.

Moisture and air

It is important to get the moisture levels of your compost right. Too wet and the compost becomes slimy; too dry and the composting process will slow down and might even stop.

To test the moisture level, squeeze a handful of the composted material. Ideally it should feel about as damp as a wrung out sponge.

If the compost gets too dry, add more 'greens' or sprinkle it with some water. If it gets too wet add more scrunched–up paper and give it a stir.

The tiny organisms that make your compost need air just like us. Introduce air into your bin either by using a garden fork to mix the material, or by adding more scrunched up paper and card, which will help to form air pockets.

Frequently asked questions

When is my compost ready to use?

The composting process is complete when the compost is dark brown and has an earthy smell. At this stage it is best left for a month or two to ‘mature’ before use. Don’t worry if it is not fine and crumbly like ‘shop bought’ compost. (This is sieved before it is marketed to produce a fine lump free product.) Your compost may be lumpy, sticky or full of eggshells and partially decomposed twigs. It will still be quite usable, the plants will not complain.

One good method to determine if compost is ‘ready’ is to break a twig in half. If the inside is dark brown with no sign of 'green' the twig has composted sufficiently to be used along with the other compost as a soil improver or mulch. The twigs that still have ‘green’ inside can ‘go round again’

How long does it take to make compost in my bin?

This is dependant on a number of things. The general rule is about a year. The more you put in your bin the more rapidly the material will compost. Also the warmer the weather the faster it will compost. So in a warm climate it can take as little as 6 weeks and under cooler conditions it can take up to 12 months to produce compost. If you can place your bin in a sunny spot it will further help to speed it up, though this is not vital. You will notice that the process slows right down during the winter months, however it is important to carry on using your home compost bin during this time. A bin that contains a good balance of browns and greens chopped into smaller pieces with good aeration and moisture will decompose a lot faster than when one or all of these factors have been ignored.

Why isn’t my compost rotting down?

There could be a few reasons for this; you will need to look in your bin to work out what the remedy is.

The composting process slows down in the winter. This is because the micro-organisms are too cold to work quickly. To help speed the process up you can add an ‘activator’. Animal pet bedding or a couple of shovels of manure are excellent compost activators. Urine can be used too, but dilute 1:4 or it will be too salty for the worms.

If it looks too dry, either water it or leave the lid off and get some rain in it. Be sure to add more greens in the future. Your compost should have the consistency of a damp sponge.

If it looks to wet add some scrunched up cardboard and more browns, this will help to absorb the moisture.

Why does my compost bin smell?

Compost should have a sweet earthy smell. For the composting process to work properly materials, moisture and air is needed. A compost bin that does not have enough oxygen will turn anaerobic. That is to say, that in the absence of air, the composting micro-organisms stop working to be replaced by another type, which work without oxygen. The by-product of their activity is a smell similar to rotten eggs. The solution is to re-introduce air into the bin to allow the ‘good’ micro-organisms to continue their work, causing the bad smells to disappear. Add scrunched up cardboard egg boxes and toilet roll tubes.

A strong smell of ammonia usually denotes that there is too much green material in the compost bin. Adding more brown material will restore the balance.

I have read that it is best to layer different materials within a compost heap. Is this correct?

The logic behind this idea is to ensure that there is a good mixture of ingredients within the heap. However, layering is not as good as mixing. A solid layer of grass cuttings can suffocate your heap. Instead ensure grass is mixed in with browns, such as fine woody waste or screwed up paper and card (remember flat pieces of paper / card will prevent air from circulating). By mixing all of the ingredients before they go into the compost bin, you can ensure that there are air pockets evenly distributed throughout the heap.

You don’t have to worry about layering or mixing your compost heap if you do not worry. Composting is a natural process and your materials will break down anyway, but you may have to be more patient!

My compost bin is infested with lots of little flies, how can I get rid of them?

These are fruit flies, they are completely harmless. They are tiny, about the size of a midge, and are either black or a white colour. They help break down the fruit and vegetable material in your bin and are an inevitable part of the composting process. In the summer their population increases and they can become a nuisance when you remove the lid of your bin. To help reduce their numbers, make sure that you bury any fruit and vegetable scraps under some other material or wrap them in newspaper.

You can leave the lid off for some time if you like, this will allow them to fly away and let fruit fly predators into your compost bin. Don’t be tempted to add fly spray as this will kill off other useful creatures in your bin.

I have seen woodlice in my compost bin is this normal?

Yes! Woodlice are essential in breaking down the wooded and carbon rich material within the compost bin. To save strawberries from attack by the woodlice sift the compost before mulching around the strawberry plants, this should remove or at least make visible any woodlice left in the rotted material.

Bees seem to be nesting in my compost bin

It is most likely that it is bumblebees that have taken up residence in your compost. In fact you are very lucky because bumblebees are in fact endangered. It is illegal to kill them.

If possible I would advise that you carry on filling your compost bin as the nest will be empty by October / November and may then be removed without fear of being stung. They never swarm like honeybees and rarely reach more than seventy bees in a colony. Once you have removed the nest leave the remains in a sheltered place in the garden. Do not leave the nest in the bin as you may end up with a dozen or so nests the next year.

I’ve got ants in my bin, how do I get them out?

Ants are one of many creatures that can colonize a compost bin. As with most of these creatures ants are harmless and are in fact beneficial for the heap. This is because they make tunnels which help to add air to the compost. They also add potassium and phosphorous to the mixture. If you do wish to remove the ants from the bin, disturb them as much as you can by turning the compost. Adding copious quantities of water will also encourage them to leave (the presence of ants could be an indicator that the heap is too dry). Adding onions should also discourage the ants away from the bin.

My compost bin seems to attract slugs

Your compost bin is a great feeding ground for slugs and snails as they help to break down your compost. Many people take advantage of this by putting them in the compost bin. This way you know exactly where they are and because you are regularly feeding them, they have no reason to leave your bin and munch your lettuces. They will keep moving up the bin to get to the fresh material, eventually dying of old age in your heap, fat and happy! It is unlikely that any slug eggs laid will survive whilst in the bin as they will either be predated on or decompose as they become compressed within the heap. Ensure that all of your compost is fully decomposed before using it on your garden.

Can I compost evergreen leaves?

Evergreen trees and shrubs have waxy leaves that break down very slowly in a compost heap. Large quantities can successfully be composted when mixed with equal quantities of grass cuttings, shredding first will help them to compost faster.

You may wish to compost them separately to make a more acidic compost. This is ideal for rhododendrons, azaleas, blueberries and other acid loving plants, as normal compost is slightly alkaline.

Pine needles are also high in acid and resin, and need to be treated in the same way. Laurel leaves contain cyanide so make sure you wear an appropriate mask over your face and stand up wind if you shred them. The poison breaks down into harmless by-products during the composting process.

Can I compost rhubarb leaves?

Yes, rhubarb leaves are poisonous when eaten. However when they are composted they decompose and are completely harmless.

Can I put windfall fruit into my compost bin?

Yes you can. It the fruit can be squashed before adding, it will decompose a lot faster. You should also be aware of fruit being a 'green' so be sure to add some 'brown' material to keep the correct balance.

Can I put Leylandii prunings into my compost bin?

Leylandii and other evergreen material take a long time to decompose, over five years in some cases. In general they are very acidic and the leaves or needles tend to have an almost rubbery texture, which repels microbial attack. Decomposition can be speeded up by shredding them or by running a lawnmower over them if the branches are not too thick. Large quantities which would fill a compost bin should perhaps be taken to either of Bristols two main Recycling Centres.

Can I put citrus fruits into my compost bin?

Citrus fruits can make your compost heap overly acidic so only add them in moderation or not at all. If you do add them, add plenty of other matter (such as grass clippings) at the same time to try to even up the balance a bit.

Also, many types of compost heap worms, such as tiger worms, don't like d-limonene, an antiseptic substance found in fresh citrus peel. The d-limonene disappears as the peel rots though so your worms will prefer it if you leave it out of the main compost heap until it's green and furry.

Can I compost ashes?

It depends on the type of ash.  Ashes from coal or coke contain sulphur dioxides so should not be added.  Charcoal briquette ash can contain chemicals to assist burning so should also be avoided.  Wood ashes or those from pure charcoal are excellent sources of potassium, however they should only be added sparingly, as they are highly alkali and can interfere with the composting process.

Can I compost pet ‘poo’?

Cat and dog faeces (and other meat eating animals) carry many harmful pathogens. However you can compost the bedding material from naturally vegetarian pets such as rabbits, guinea pigs, gerbils, and even cows and horses. The urine and droppings act as a 'green' (nitrogen rich) and the bedding material acts as a 'brown' (carbon rich). Together they are a great addition to a compost heap and will help speed up the breakdown of your compost. Suitable bedding materials include wood shavings and sawdust, straw and hay, untreated paper and cardboard products.

Can I add shredded paper to my compost bin?

Increasingly people are becoming nervous about putting receipts and personal documents out with their normal rubbish. The best thing to do with these kinds of documents is to screw them up and put them in your compost bin along with any fruit and vegetable peelings. Within a couple of weeks the paper will be unreadable. Shredded paper does not compost so well because it does not have air pockets trapped in it. It is better to screw up paper rather than shred it.

Can I compost all types of paper and card?

In general people have a predominance of 'greens' in the garden, e.g. grass cuttings and plant material. But composting 'greens' on their own will make a slimy, smelly mush. Paper and card are classed as 'browns', and play an important role in creating air spaces within your compost heap.

We recommend that you don’t compost newspapers, but recycle them in your black box or at one of Bristol's Recycling Centres. They are best recycled, and there is so much other paper and card that can be composted that isn’t suitable for recycling. When you start composting paper and card you will be amazed by how much your rubbish is reduced. Whether it’s junk mail, cereal packets, toothpaste packaging, biscuit cartons, solid tissues, old envelopes, confidential documents or toilet roll tubes, it can all be composted.

Don’t tear into little flat pieces, instead screw up the paper and card. This traps air pockets and provides structure within your heap.

Tests show that inks and glues also break down harmlessly. Avoid cardboard containers, used to hold liquid, (tetra-pak) as these are often lined with plastic and or foil.

My eggshells do not break down, what should I do?

Eggshells do not strictly decompose which is often the reason why people don’t like to include them in their compost bin. They do, however break down into smaller and smaller fragments as the material is mixed and should be barely noticeable in the finished compost. They are an important source of calcium and as such should not be excluded.

Their breakdown can be assisted by crushing them before they are added to the compost bin. To speed up their decomposition, cook the shells in an oven to make them brittle and cause the membrane to dry up which is the part that keeps the shell together.

Is it a good idea to add activators to my compost bin?

You do not need to buy activators, they are expensive and there are free, natural alternatives. Activators work by adding nitrogen. Grass cuttings are a natural activator and will help speed up the breakdown of your compost. Do not put solid batches in, as too much grass will produce a slimy, smelly mush. If you have grass you will not need any other activators. If you don’t have any grass cuttings, nettles (not the roots), comfrey, and seaweed are free alternatives or, if you’re feeling brave, urine! Urine is sterile and crammed with minerals and vitamins. Don’t be coy about it, this is an excellent activator and saves water from being flushed down the toilet!

Will my compost heap heat up enough to kill off weeds and plant diseases?

Some heat can be generated in your compost heap. The more waste that you put into your compost bin at any one time, the greater the amount of heat generated. High temperatures can be achieved in large compost heaps especially where grass cuttings are incorporated. If you put your hand in a pile of grass it can get quite hot only a few hours after being cut. However, you are unlikely to generate high enough temperatures to kill off weeds in the compost bins provided by Bristol City Council.

You do not need to generate heat in order to make compost. However, you do need to be a bit careful about which weeds you put in the bin. The last thing you want to do when you spread your compost around your garden is to also spread weed seeds around! Instead of putting weeds into your compost bin, put them in a black sack in the sun for a couple of months until they are dead and turn into slime. Then add them to your compost heap. Annual weeds can go straight into your compost. All weeds that have turned to seed and perennial weeds should be avoided, particularly those with taproots or weeds that spread via rhizomes.

Common culprits include celandine, bulbous buttercup, ground elder, crouch grass and bindweed; give them the black sack treatment.