Advertisement

A beginner's guide to making garden compost

It’s good to have two heaps, so you can fill one while the other rots down
It’s good to have two heaps, so you can fill one while the other rots down

Autumn and early winter sees an abundance of green waste being generated from tree pruning, fallen leaves and so on. Finding ways to use or dispose of this debris can be a horticultural headache. Home-made garden compost is the answer: a gardener’s secret weapon, this black gold is the key to a thriving garden, increasing biological activity in the soil and improving its structure and texture.

Use it to mulch borders in autumn or spring, or to add goodness to the vegetable plot. Garden compost can be dug in or, if you follow the no-dig method, spread on the soil surface. Over time, as you add compost to your garden, you’ll notice a real difference to plants, which also makes a difference to our environment.

What is garden compost?

Garden compost differs from the type of compost bought in bags for potting up container plants and growing from seed. Compost from bins and heaps is full of life, which adds to soil health, but it is not ideal for potting because it’s not sterile and can harbour weed seeds and diseases that affect seedlings and young plants.

Bagged compost is made from organic matter, loam, sand and fertilisers, which have been treated to be sterile, making it safe for seedlings but very limited when it comes to stimulating biological activity in the soil.

How to make compost

Top tips for success

There’s no magic or secret to making good compost from garden waste. For success, we need to create an environment that is conducive to getting hard-working soil bacteria and micro-organisms to break down the green waste. Ideally, we’re looking for a firm, moist compost heap that is not soggy.

Good garden compost should be crumbly, dark in colour, and sweetly scented. If it smells rotten, it’s not ready to use.

It’s a good idea to have two compost bins or heaps, if space allows. The idea being that you can be filling one bin while the other is rotting down, and by the time you’ve filled the second bin, the first is ready to be emptied.

There's no secret trick to making good compost from waste, says Tom - Getty
There's no secret trick to making good compost from waste, says Tom - Getty

Ideally, a heap should come into contact with the soil to allow bacteria to reach the compost – but if that’s not possible, add a shovelful of old compost or garden soil to the heap once a month to introduce those communities.

Aim for a bin or heap that is around one cubic metre, which is large enough to generate the heat necessary for breaking down waste. You can make your own bin with pallets or mesh, or buy a plastic compost bin online.

However you go about this, ensure that the heap is covered with a piece of old carpet, a lid or a piece of tarpaulin to trap the heat inside and prevent rain from saturating the compost.

Trouble-shooting

Soggy and smelly compost – you’ve probably gone overboard with too many lawn clippings without balancing out the fibrous material. Pop in some shredded paper or cardboard more regularly.

Citrus peelings that won’t rot – your main problem is likely to be a lack of moisture. Add a watering can of water once a week.

Rodent activity – avoid cooked food and invest in a metal compost bin with a mesh base to prevent them from getting into the heap.

Slow breakdown – grass clippings applied little and often add nitrogen and heat, which moves things along.

In addition, try adding a layer of farmyard manure every so often, which also provides bacteria and heat. Shred any twiggy material and tough leaves to unify the rotting process across the whole heap. Finally, turn the material, if possible, to aerate and reinvigorate the biological processes.

The happy heap

Balance is the key to a good compost. You need to aim for a 50/50 mix of soft green waste and fibrous brown material. When we glance at our wheelbarrows, very rarely are they equally divided into such perfectly proportioned quantities, but fear not – as long as your heap becomes balanced over time, and you prevent one type of material from becoming too dominant, you’ll be okay.

⇒Green/soft material to add nitrogen

⇒Vegetable peelings

⇒ Grass clippings

⇒ Spent cut flowers or deadheads

⇒ Annual weeds

⇒ Fibrous and woody (carbon-rich material)

⇒ Herbaceous stems

⇒ Spent bedding plants

⇒ Woody prunings – cut into small pieces or shredded to accelerate breakdown

⇒ Fallen leaves

⇒ Eggshells

⇒ Shredded paper

⇒ Cardboard

⇒ Soft hedge clippings

What to avoid

⇒Cooked food waste

⇒Meat and bones

⇒Perennial weeds, such as dandelion, bindweed, ground elder and docks

⇒Diseased plant material, such as tomatoes affected by blight

⇒Dog and cat waste

⇒Weed seed heads

Tom Brown is head gardener at West Dean Gardens, West Sussex. Follow him on Twitter @HeadGardenerTom; and on Instagram @tombrowngardener