How to Make Compost

How to Make Compost. It should be a simple matter, and it is, really. But sometimes it goes horribly wrong. This blog is based on the gardening compost topic in Plews’ Gardening Lessons. Although students don’t get the photos, just to stand and stare at their own compost heaps and compost bins.

Some possess liquid gold in their gardens, others have a smelly heap. Some have a compost bin full of organic matter that isn’t decomposing and they don’t know why. And some have an empty space where they would like to have compost bins.

And it’s not just a topic for gardening lessons. The whole issue of compost can come up in Garden Consultancy visits too. For all my lovely students and consultancy clients past and present: this is for you.

What is Compost?

Compost is decomposed organic matter which gardeners use to improve the health, nutrient levels and texture of the soil in their gardens.

The basic rule for making compost is to have a roughly 50:50 ratio of green, nitrogen rich material to brown, carbon rich material.

When you first start composting it can be helpful to think in terms of layering your greens and your browns. This enables you to see more clearly if the proportions are roughly half and half. But you don’t have to keep (or even start) with strict layers. It is the ratio of nitrogen and carbon which is important.

How to Make Compost – What to put in it

Green material

green / living leaves
soft green stems when you’re cutting back
flowers from the house when they’ve ‘gone over’
top growth from perennial weeds
annual weeds (no seedheads if possible)
windfall apples and over ripe fruit (although be aware that these should be disease free and not fermenting)
grass cuttings
vegetable peelings

Brown material

dead leaves (see below)
twigs
ripped up newspaper and lightweight cardboard, such as egg boxes
coffee grounds, tea leaves (some consider these to be green)
eggshells
straw
paper towels and bags

Only include small amounts of

larger branches, shredded if more brown is needed
some leaves take a long time to rot down, eg oak, so may be better composted separately. See blog link below
wood ash
hair and nail clippings
natural fibres, eg wool

Can be composted, but not in a cold composting system as they take longer to decompose. So compost separately

bedding (with poop) from herbivore / vegetarian pets, eg rabbits and guinea pigs
poultry manure
manure from herbivores / grass eaters such as horses and cows

Do NOT include home composting systems

carniverous animal poop – dog, cat
perennial weeds roots
diseased plants or plant material
weed seeds
coal ash
disposable nappies (you really wouldn’t believe some of the compost bins people have inherited!)

Can be included in certain home composting systems such as Bokashi

cooked food waste
bones

How to Make Compost – Actually Getting Started

We start with the related topics of choosing and placing your compost bin in your garden. Just a few key points.

Where should you place your compost bin? This can be a tricky question in smaller gardens. There are decorative styles around if your compost bin is on view.

If you’re going to have your compost bins in a separate utility area away from the house, remember to make it easy to get there. Have a separate small, closed container as a ‘holding store’ near the kitchen door. That way you don’t have to traipse down the garden when its pouring with rain.

For cold composting, you can:

buy wooden or recycled plastic compost bins
make a bin out of wood, new or recycled
have a compost heap rather than a contained bin

A small household, a small garden may find one compost bin is enough for the waste generated. Larger gardens and households will need 2 or 3 compost bins, plus room for leaf composting.

Critical point to consider – how will you access the ready-to-use compost at the bottom of the bin? This is more important where there is only one bin as it will be in constant use. If you’re buying a compost bin, check there is an access door or flap at the bottom. Where there are more bins, you would operate on a rotating system of fill, leave to compost, use in the garden.

Should you place your compost bins on soil, concrete, weed suppressing membrane, slate chippings, wooden slats…?

Good question. To be perfectly honest, it depends on you, your garden (small, large) whether there is a rat or perennial weed problem. There are pros and cons to each of the above. So there is no one answer. But there are a few key points –

if perennial weeds are a problem, site your compost bin on a hard surface
if rats and mice are, or maybe a problem, use a sealed compost bin. Site on a solid surface for extra security
if sited on a hard surface, you will need to add worms and compost eating slugs to your compost bin to help with the decomposition

Filling the Compost Bin

start with a layer of twigs to enable air to flow through. air is an essential part of the cold composting process
then throw in a layer of green garden and kitchen waste
a layer of brown or a thin layer of your garden soil with worms
continue with green / brown mix

I suggest that the layers of brown and green materials should be alternated, at least initially. This is to help you get used to working with that ratio of half and half.

However, most domestic situations are not going to give you regular, convenient quantities of green and brown from which to create neat layers. So don’t worry; there are other tricks you can use to maintain that balance. For example, if you’ve just added a trug full of dead headed flowers and a pot full of vegetable peelings to the compost bin add a similar quantity of shredded paper. Job done!

Worms – you can just add some of your own garden worms into the bin. Or you can buy composting worms, such as brandling worms. Bear in mind that some of the worms sold for wormeries are not as happy in an ‘ordinary’ compost heap or compost bin as the mix – their food – may not be right. You never knew some worms had haute cuisine appetites, did you?!

Turning the Compost

The point about turning the compost is to ensure that enough air is in the mix to enable the microbes and other beasties to do their work. In some composting systems it isn’t necessary to do this; in cold composting it might be.

Despite aiming to mix your green and brown, sometimes the material all compacts down. And you don’t notice until you try to get some out of the access hole at the base of the bin. All you can see is a lump of what looks like compost but needs diggings out of the bin like hard clay might. Possibly when you do get it out, its not quite the sweet smelly mix it should be but is very slightly rancid.

Hopefully, the situation is resolvable and the compost useable. Do this by aerating the compost in the bin and starting again with green and brown twiggy layers interspersed with your solid mass.

But you should review your compost making methods and it may pay you to think about turning your compost to prevent it happening again.

Check out the video below for how to turn your compost. This shows tipping the compost out of the bin. It can be a satisfying task. And if you wanted to access the compost anyway, in the autumn say, to mulch your borders, then it’s no real extra effort.

For those who don’t have the room to do that, or the physical strength, or even the inclination, there are other ways of aerating your compost bin.

Use a corkscrew. I do feel someone had this idea on a Friday evening! It’s basically a large corkscrew or prong that you stick into the compost bin to turn the compost on a regular basis. Made of recycled plastic, it is lighter weight than using a garden fork, and a better design for the task. A garden fork will do the job (and has done for hundreds of years) but in the confined space of a compost bin a specialist tool does the job better.

How to Make Compost – what next?

Having written the above, and still able to continue writing on the topic of compost, I have taken notice that you’ve finished your cup of coffee and will draw to a close. At least for now. Read the blogs below (there are further links in those) and view the video for some more information.
I will return to the subject again, as composting, even on a small scale, is in my opinion, critical to the way we deal with issues such as landfill.

If you’d like a Gardening Lesson on composting, a Garden Consultancy visit to sort out your composting issues, or a Garden Designed complete with compost bins, bespoke to you if you would like, do please get in touch.

Till then, happy composting!