Getting to Know Your Soil

Before you buy a single plant, get your hands in the ground.

It sounds obvious, put like that, but hardly anyone does it. We fall for a plant at the nursery, bring it home, dig a hole, and only later — when it sulks, or rots, or refuses to flower — do we wonder whether it ever wanted to live in our particular patch of earth. Almost every planting disappointment I’ve had traces back to the same thing: I planted what I liked, rather than what the soil could support.

So this is the least glamorous and most useful afternoon you’ll spend in the garden. Getting to know your soil. There are two things worth finding out — what it’s made of, and how acid or alkaline it is — and neither needs a kit or an expert. Just a trowel and a bit of curiosity.

Soil comes, broadly, in six types: clay, sand, silt, loam, chalk and peat. In most gardens you’re dealing with one of the first four, or some blend of them, and each behaves in a way you can feel in your hands.

Clay is the heavy one. Sticky and mouldable when wet, it bakes hard and cracks in summer, and it holds onto water and nutrients so well that it can be genuinely fertile — once you’ve stopped cursing it. Sand is the opposite: light, gritty, quick to drain and quick to dry, easy to dig but forever thirsty. Silt sits between the two, smooth and fairly moisture-retentive, fertile but inclined to compact. And loam — the blend of all three that most of us are quietly hoping for — is the one the books call perfect: fertile, well-drained, easy to work, and forgiving of almost anything you plant in it.

You can find out which you’ve got in about two minutes, and the method is exactly as undignified as it sounds.

Take a small handful of soil, add a little water, and try to roll it into a sausage. If it rolls easily and you can bend that sausage into a ring without it breaking, you’ve got clay — it’s the stickiness that lets it hold the shape. If it won’t hold together at all, crumbling apart no matter what you do, that’s sand. And if it does something in between — rolls, but cracks and falls apart when you try to bend it — you’re somewhere in loam country, which is exactly where you want to be.

That’s the whole test. It tells you the texture of your soil, which governs how it drains and how it holds food and water. What it can’t tell you is the other half of the story.

Here’s the thing the sausage test won’t reveal: how acid or alkaline your soil is. And for a good number of plants, that matters even more than the texture.

This is measured as pH, on a scale where 7 is neutral. Below that is acidic; above it, alkaline. Chalky soils are the alkaline ones — full of calcium carbonate, often pale and stony — and they rule out a whole cast of acid-loving plants no matter how well you feed them. Peaty soils, dark and spongy and rare in gardens, tend the other way, towards acid.

The catch is that a clay soil can be acidic or alkaline; so can a sandy one. Texture and pH are two separate questions, which is why you can’t read one off the other. A cheap pH testing kit from the garden centre will settle it in minutes, but your neighbours’ gardens are the better guide: if every front garden on the street is heaving with rhododendrons, camellias and azaleas, you’re on acid soil. If nothing acid-loving thrives for miles, you’re likely on chalk. Plants have been running this experiment for years. Read their results.

Once you know both things, the whole business of choosing plants gets easier — and a lot less heartbreaking. You stop fighting your ground and start working with it.

On clay, lean into the shrubs that relish the moisture and richness: hydrangea, viburnum, mahonia, the birches. On sand, reach for the plants built for drought and sharp drainage — lavender above all, but also achillea, cotoneaster, the airy grasses and Mediterranean things that would rot in heavier ground. On chalk, that same drought-tolerant, sun-loving cast tends to thrive: lavender again, ceanothus, hardy geraniums, clematis. And on peat or acid soil, you finally get to grow the things chalk gardeners can only envy — camellias, rhododendrons, azaleas, the whole ericaceous tribe. If you’re one of the lucky ones on loam, the honest advice is to grow more or less whatever you fancy.

This is the same lesson that runs through The Case for Doing Less — right plant, right place, rather than bending the conditions to suit your wishlist. Knowing your soil is simply how you find out what “right” means for your garden.

Not really — and it’s worth being clear-eyed about this, because a lot of effort gets wasted trying.

You cannot turn clay into sand, or the reverse. The quantities you’d need to shift the texture are frankly absurd; you’d be barrowing in material by the tonne to make any real difference. Trying to change your pH is a similar losing battle — you can nudge it briefly, but the soil drifts back to what it wants to be, and if you crave acid-lovers on a chalk plot, the sane answer is to grow them in pots of ericaceous compost rather than wage war on your whole garden.

What you can do — and should, whatever you’re working with — is improve the soil you have. Organic matter is the answer to almost everything here: well-rotted manure, garden compost, leafmould, composted bark. Spread over clay it opens up the drainage; spread over sand it helps the ground hold onto moisture and food. The same simple material fixes both opposite problems, which never stops feeling like a small miracle.

The easiest way to add it is to lay it on the surface, a good two or three inches thick, over soil that’s already moist — late winter or autumn is ideal, when the ground is damp but not frozen or waterlogged. Then let the worms do the digging for you. They’ll pull it down over the following months far more thoroughly, and far less disruptively, than any fork.

Which is, when you think about it, the whole philosophy of the garden in miniature: learn what you’ve got, work with it rather than against it, and let nature do the heavy lifting wherever it will.