Why soil is the foundation of a wildlife garden

It is easy to think of a wildlife garden as something that happens above ground. You plant lavender for the bees, hang a bird feeder, and leave a corner of nettles for the butterflies. But beneath your feet is a hidden world doing most of the heavy lifting, and it is far busier than you might imagine. A single teaspoon of healthy garden soil can contain billions of bacteria, several metres of fungal threads, and a whole community of microscopic creatures. Get this underground ecosystem right, and everything above it thrives.

Soil is not simply a substance that holds plants upright. It is a living system that stores water, unlocks nutrients, and recycles dead material into new life. When it is healthy, it needs very little input from you. When it is degraded, no amount of feeding or watering will fully compensate. The good news is that soil responds remarkably quickly to kindness, often within a single growing season.

Meet the residents: worms, fungi and bacteria

Earthworms are the most visible members of the soil community, and they are worth celebrating. As they move through the ground they pull down fallen leaves, aerate the soil, and leave behind nutrient-rich casts. A garden with plenty of worms is a garden that is processing its own waste. You can check on yours simply by digging a spade's depth into a bed and counting what you find.

Less visible but equally important are the fungi. Some form fine threads that stretch far further than the plant's own roots, effectively extending them and helping to ferry water and minerals in exchange for sugars. This partnership, known as mycorrhiza, is one of nature's oldest alliances. Bacterial life, meanwhile, breaks down organic matter and makes nitrogen and other nutrients available to plants. Together these organisms create the sticky, crumbly texture that gardeners call good tilth.

• Worms aerate soil and drag leaf litter underground.
• Fungi extend root reach and help plants access water and nutrients.
• Bacteria recycle organic matter into plant-available food.
• Beetles, springtails and mites shred debris and keep the whole system moving.

Encouraging this community means keeping disturbance to a minimum. Every time you dig or rotovate, you slice through fungal networks and turn the soil's natural structure upside down. Try no-dig methods where you can: lay compost on the surface and let the worms do the incorporating for you.

Mulching: a blanket that feeds the soil

Bare soil is a wasted opportunity. Left exposed, it dries out, loses nutrients to rain, and warms too quickly in summer. A mulch of organic matter solves all of these problems at once. Spread a layer five to eight centimetres deep around shrubs, perennials and vegetables, taking care to leave a small gap around stems to prevent rot.

Good materials include garden compost, well-rotted manure, leafmould, and bark chippings. Leafmould is particularly valuable and completely free: gather autumn leaves into a bin bag, punch a few holes in it, and leave it for a year or two. The dark, crumbly result is a superb soil conditioner that mimics the forest floor. Mulching also suppresses weeds, which means less hoeing and more habitat left undisturbed for overwintering insects.

It is worth remembering that mulch feeds the soil, not the plant directly. The worms and microbes break it down slowly, releasing nutrients at a pace that suits growing roots. This slow-release approach avoids the surge of soft, sappy growth that liquid feeds can produce, which is often more attractive to aphids.

Composting: turning waste into wildlife

A compost heap is one of the best wildlife features you can add to a garden. It is a warm, damp, food-rich habitat that supports worms, beetles, slow worms, and even grass snakes in larger plots. It also gives you a free supply of the finest soil conditioner available.

Aim for a mix of roughly two parts brown material to one part green. Browns are dry and carbon-rich, such as cardboard, torn paper, and dead stems. Greens are moist and nitrogen-rich, such as grass clippings, vegetable peelings, and spent plants. Turn the heap occasionally to add air, and keep it as damp as a wrung-out sponge. If it feels slimy, add more browns; if it is dry and doing nothing, add greens and a splash of water.

Do not add cooked food, meat, or diseased plant material to a standard heap, as these attract rats and can spread problems. A separate wormery is a neat solution for kitchen scraps in smaller gardens, producing both liquid feed and rich castings. If you can, site your bin on bare soil so that worms and other creatures can move in freely from below.

Why chemicals do more harm than good

Weedkillers and insect sprays do not discriminate. A product designed to kill aphids will also harm ladybirds, hoverflies, and ground beetles, and residues can linger in the soil where they disrupt the fungi and bacteria you have worked so hard to nurture. Slug pellets are a particular concern, as they can poison hedgehogs, birds, and pets.

The wildlife gardener's alternative is to build resilience rather than reach for a bottle. Healthy soil grows stronger plants that shrug off pests more easily. Encourage natural predators by leaving some untidy corners, planting nectar-rich flowers to feed adult hoverflies, and tolerating a little damage. A few nibbled leaves are a small price for a garden that teems with life. Hand-weed annuals before they set seed, and use mulches and dense planting to crowd out the rest. If a plant is constantly riddled with pests, it may simply be in the wrong spot.

Simple habits that build healthier soil

You do not need expensive equipment or a science degree to improve your soil. Small, consistent actions add up over the seasons.

• Leave the leaves: rake them into borders or make leafmould instead of binning them.
• Cut back on digging and let worms do the mixing.
• Keep soil covered year-round with mulch or green manures such as field beans or phacelia.
• Add compost every spring and autumn rather than relying on fertilisers.
• Avoid walking on wet beds, which compacts soil and squeezes out the air pockets life depends on.

Treat your soil as a living partner rather than an inert growing medium, and the rewards go far beyond healthier plants. You will see more worms, more birds hunting them, more flowers setting seed, and a garden that quietly gets better with every passing year.