To everything there is a season (‘turn, turn, turn’ – you’ll be singing that all day now, sorry). A time to live and a time to – let things softly and quietly decompose back into usefulness. This is the season of clearing up and making compost heaps, and tapping into the cycle of (cue some more singing) life. It all starts and ends in the soil, because the soil is the basis for all life in the garden. A healthy soil will be performing microscopic miracles under your feet; feeding your plants, fighting disease and giving a home to countless millions of creatures. So many that, did you know (and I’m still reeling from this), that a teaspoon of garden soil contains more organisms than there are people on the earth? Think about that when you’re cleaning the dirt out from under your fingernails…

Soil Biology

The complex web of interconnections in the geology, biology and chemistry of the elements in the soil are only just beginning to be understood – new discoveries about the chemical conversations between plants and their soil environment are being made all the time and the more we begin to understand what’s happening within the soil, the more mysterious and complicated it gets. We only see the monsters that patrol the soil – the moles, earthworms, beetles, slugs, centipedes, but just as important are the fungi, nematodes, protozoa, bacteria and numerous other microbes. Plants rely on a huge team of microscopic organisms, some of them, like fungal micorrhiza (and some nitrogen-fixing bacteria), actually living symbiotically within plant roots, trading sugars for vital elements that the plants need. This is the living part of the soil, but the dead part has a big part to play too. It’s made up from plant and animal remains – living things that have recently died and not yet decomposed into their chemical constituents. This organic matter is known as humus (not to be confused with a well known Middle Eastern dip). A soil rich in humus makes a comfortable home for all its inhabitants.

Making compost

There are two main types of compostable material – nitrogen releasing, or ‘green’ waste and carbon releasing, or ‘brown’ waste. These need to be added to the compost heap in roughly equal measures and should also be well mixed. If too much ‘green’ stuff is added the heap will become a stinky mush and if too much ‘brown’ stuff is put on it will take ages for the heap to rot down. So green waste is grass clippings, kitchen waste (i.e. veg and fruit peelings), weeds, top (leafy) growth and brown waste is stems, woody growth, paper and card.

The other vital ingredients to the compost heap are air and water. The heap needs to be moist, but not wet. Water if it seems dry, but cover with an old piece of carpet or a lid of some kind to prevent the heap from getting too wet, as this will slow down the decomposition, especially in the winter. There needs to be sufficient air getting into the heap for the beneficial bacteria to do their work. Too little air will result in the anaerobic bacteria taking over and making the heap into a nasty, stinky mess. This is why heaps of grass clippings with no other courser, fibrous additions become so horrible and slimy. Shred woody stems and tough leaves (like holly and oak leaves), as these contain lignin, which will take a long time to break down. Adding activators (substances containing bacteria that readily break down organic matter) such as manure, existing well-rotted compost, garden soil, or shop-bought activators like Garrota speed up the process. Regular mixing or turning over of the ingredients in your heap will also help. The ‘tumbling’ compost maker bins work on this principle and should make compost within 3 months or so. Your compost is ready to use when it is a rich brown colour. It should smell nice(!) and earthy.

What you can’t compost

• Cooked food and meat (which could attract vermin)

• Plastic, metal, glass etc

• Man-made fibres

• Dog and cat waste, as it contains dangerous pathogens

What you can compost

• Garden debris – prunings, tidy ups, vegetable garden waste

• Kitchen waste – raw peelings (but not potatoes, which may carry blight), tea bags, egg shells etc

• Household rubbish – cardboard, paper, loo roll, egg boxes (scrumpled up to add air to

the heap and give homes to insects and beneficial invertebrates)

• Contents of the hoover bag (unless it’s crammed with lego)

• Hair, wool, cotton, nail clippings (will take a while to break down)

• Wood ash (not coal ash)

• Vegetarian pet waste – if sawdust is used as bedding this will take a while to compost

Weeds can be composted (in theory) if your heap is hot enough to destroy the seeds or the persistent roots of perennial weeds. In practice, most of us have cold heaps that don’t reach the right temperature to kill weeds. I prefer to treat them separately and either burn them or let them rot in a bucket of water (think of it as revenge) before adding to the heap/making fertiliser. You can make a special ‘tea’ by leaving the young leaves of nettles or comfrey in a bucket of water for a few weeks – you’ll know when it’s ready by the horrific smell… then dilute it in a watering can and use as fertiliser. Yummy.

A healthy soil will be performing microscopic miracles under your feet; feeding your plants, fighting disease and giving a home to countless millions of creatures

There are two main types of compostable material – nitrogen releasing, or ‘green’ waste and carbon releasing, or ‘brown’ waste

Your compost is ready to use when it is a rich brown colour. It should smell nice(!) and earthy

Leave a log pile in the corner of your garden to attract wildlife

• words: Jo Arnell

You may also like

In the Night Garden

Jo Arnell explains how to make the most of your outdoor space once darkness falls Some enchanted evening you may see me outside – mainly searching for slugs in the garden, because the cool hours of night are when they...

Contain your excitement

Jen Stuart-Smith discusses how to get creative with your pots and planters My love affair with plants started with houseplants when I was a child. As my bedroom windowsill overflowed – resulting, occasionally, in waking up with compost under my...

More than just a pretty face

Jen Stuart-Smith explores the multiple uses of some easy-to-grow garden favourites When you grow flowers for their beauty, shape and colour it can be easy to forget all the other qualities they have to offer. Some are edible, others provide...