GrowingHQ

Work out what you have

Half an hour, a spade and a bottle of vinegar will place almost any garden. Each test below is genuinely reliable about one thing and completely silent about the rest, and the second half is stated as plainly as the first.

None of this is a laboratory test, and it does not pretend to be

A laboratory returns a pH number and figures for phosphorus, potassium and magnesium. Everything on this page returns a class: sandy or clay, acid or alkaline, draining or not. That is enough to decide what to plant and what to improve, and it is not enough to diagnose a nutrient problem.

A home pH kit is the sharpest case. A reading of “acid” is consistent with anything from pH 4.5 to 6.4 — the span between a blueberry bed and a brassica bed — and the kit cannot separate them. Treat a kit result as a band, never as a number, and if a decision genuinely turns on the difference, pay for a laboratory test.

Why texture decides everything else

The squeeze test tells you particle size, and particle size is the mechanism behind every other property a soil has.

Why sand, silt and clay behave differentlyThree panels comparing particle size to scale. Sand has large particles with large gaps between them, so water falls straight through and nutrients wash out with it. Silt has medium particles that hold water well but form a fragile structure that caps after rain. Clay has very small particles with very small gaps, holding water and nutrients tightly so that air rather than water is what runs short. The particles are drawn at relative scale: a clay particle is roughly a thousandth the diameter of a sand grain.Sand0.06–2 mm

Large particles, large gaps. Water falls through; nutrients wash out with it.

Silt0.002–0.06 mm

Medium. Holds water well and the structure is fragile — it caps after rain.

Clayunder 0.002 mm

Tiny particles, tiny gaps. Holds water and nutrients tightly; air is what runs short.

Drawn to relative scale. Everything else about a soil's behaviour follows from this one difference, and it is the property no amount of compost changes.
The soil pH scale and where common crops sitA horizontal pH scale from 3.5 to 8.5 divided into six bands: very acid, acid, slightly acid, neutral, slightly alkaline and alkaline. Markers below the scale show blueberries sitting in the acid band around pH 4.5 to 5.5, most vegetables spanning slightly acid to neutral around pH 6 to 7, brassicas favouring neutral to slightly alkaline where clubroot is reduced, and chalk gardens sitting in the alkaline band around pH 7.8 to 8.5. The useful range for most crops is narrow, and blueberries sit well outside it.Very acidAcidSlightly acidNeutralSlightly alkalineAlkalinepH 4pH 5pH 6pH 7pH 8Most cropsBlueberry— will not grow above about 5.5Most vegetablesBrassicas— clubroot is reduced above 7Chalk gardens
The bands are what a home test kit can actually distinguish. A kit reading 'acid' spans pH 5.0 to 6.0 — the difference between a blueberry bed and a brassica bed.
How three soils behave a week after heavy rainThree side-by-side soil cross-sections a week after heavy rain. The free-draining profile, typical of sand or chalk, holds no standing water and roots reach the full depth, with drought the main risk. The moisture-retentive profile, typical of loam or silt, holds water in the pores in the lower third while still admitting air, and roots reach full depth. The impeded profile, typical of compacted clay or a pan, has standing water filling two thirds of the depth, and roots stop short at the top of the wet zone and rot over winter.Free-drainingSand, chalkno standing water

Water gone within hours. Roots have air; the risk is drought.

Moisture-retentiveLoam, siltwater table

Holds water in the pores and still admits air. What every soil is measured against.

ImpededCompacted clay, panwater tableroots stop

Water stands. Roots stop at the wet zone and rot over winter.

All three look identical from above. The difference only appears a week after rain, and it is what decides whether a perennial survives its first winter.

The tests

The squeeze test

Reliable
  1. Take a handful of moist soil from about a spade's depth — not from the surface, and not when the ground is either sodden or bone dry.
  2. Remove any stones and roots, and work it between your fingers for a few seconds.
  3. Squeeze it into a ball, then try to roll it into a sausage and bend the sausage into a ring.
  4. Rub a little between finger and thumb and note whether it feels gritty, silky or sticky, and whether it takes a shine.

What it tells you

Texture, which is the property everything else follows from. Gritty and will not hold a ball is sand. Silky and holds a ball but cracks when rolled is silt. Sticky, rolls into a ring and takes a polish is clay. Holds a shape and crumbles when prodded is loam.

What it does not tell you

Nothing at all about pH, nutrients, drainage in winter, or what is buried below the depth you dug. It identifies what the soil is made of and stops there.

The vinegar test for chalk

Reliable
  1. Take a dry lump of soil, or a pale stone from it.
  2. Drop ordinary household vinegar onto it and watch closely.
  3. Fizzing — an audible or visible effervescence — means free calcium carbonate.

What it tells you

Whether the soil contains free chalk or limestone. If it fizzes, the soil is alkaline and will stay alkaline, and no realistic amount of acidifying material will change that.

What it does not tell you

How alkaline. It is a yes-or-no answer, not a measurement, and a soil that does not fizz may still be alkaline for other reasons.

The drainage hole

Reliable
  1. Dig a hole about 30 cm across and 30 cm deep, in the part of the garden you actually want to plant.
  2. Fill it with water and let it drain away completely. This saturates the surrounding soil so the second filling measures the soil rather than the dry ground.
  3. Fill it again and note how long it takes to empty.

What it tells you

Drainage as it will behave in practice. Gone within an hour or two is free-draining. Four to twelve hours is moderate. Still holding water after twenty-four hours is impeded, and that is the number that decides which fruit trees will survive a winter here.

What it does not tell you

Why. A hole that will not drain may be sitting on clay, on a compaction pan, or in a hollow with a high water table, and the remedies for those three are entirely different.

Looking for a compaction layer

Reliable
  1. Dig a hole a spade and a half deep, keeping one side vertical so you can read the profile.
  2. Look down the vertical face for a change in colour, and for a horizontal layer where the structure looks smeared, platy or solid rather than crumbly.
  3. Push a screwdriver or a thin rod slowly down through the profile and feel for a depth where the resistance jumps.
  4. Look at where roots stop. Roots turning sideways in a flat plane is the clearest sign there is.

What it tells you

Whether there is a pan, and at what depth. This is the most useful single observation on a new-build garden, and the one most likely to explain water standing on ground that is not clay.

What it does not tell you

How far the pan extends. One hole is one hole, and compaction from machinery usually follows where the machinery went, which may be half the garden.

What is already growing

Rough impression only
  1. Look at established weeds and at neighbouring gardens, particularly at mature shrubs, which have been sampling the soil for years.
  2. Note whether rhododendrons, camellias and pieris are thriving locally, and whether they look yellow between the veins.
  3. Note whether rushes, buttercups or horsetail are present, and whether moss dominates the lawn.

What it tells you

A useful first impression. Healthy rhododendrons in neighbouring gardens indicate acid soil; the same plants yellowing indicate the opposite. Rushes and creeping buttercup indicate ground that stays wet.

What it does not tell you

Anything reliable about your own garden specifically. Neighbouring gardens may have imported soil or grow those plants in containers, and a soil test costs a few pounds. Treat this as a reason to test, not as a substitute for testing.

A home pH kit

Indicative
  1. Take samples from several places in the bed — soil varies over a few metres, especially in a garden that has been built on.
  2. Take each sample from about 10 cm down, not from the surface.
  3. Mix each with the supplied solution, let it settle, and match the colour against the chart in good daylight.

What it tells you

Which pH band the soil is in, which is enough to decide whether to lime before brassicas and whether acid-loving plants are a realistic proposition in the ground.

What it does not tell you

A number. A kit reading 'acid' covers everything from pH 4.5 to 6.4, which is the difference between a blueberry bed and a brassica bed — and the kit cannot separate them. It also says nothing about nutrient levels, which is what a laboratory test is actually for.

Matching what you found to a soil

The squeeze test does most of the work. The others confirm it and fill in what texture alone cannot say.

If it feels like thisYou haveThen read
Sticky when wet, sets hard when dry, and takes a polish when rubbedHeavy clayGrowing on heavy clay
Gritty between the fingers and will not hold a shapeSandyGrowing on sandy
Pale, often stony, frequently shallow over solid rock, and always alkalineChalky and alkalineGrowing on chalky and alkaline
The balanced mixture every soil description uses as its reference point: holds moisture without waterlogging, and works over a long seasonLoamGrowing on loam
Silky rather than grittySiltyGrowing on silty
Dark, spongy and acid, formed under waterlogged conditionsPeaty and acidGrowing on peaty and acid
The balanced mixture every soil description uses as its reference point: holds moisture without waterlogging, and works over a long seasonShallow over rockGrowing on shallow over rock
The balanced mixture every soil description uses as its reference point: holds moisture without waterlogging, and works over a long seasonMade ground and urban soilGrowing on made ground and urban soil

Two of these are not textures at all

“Shallow over rock” and “made ground” are defined by what is underneath rather than by what the topsoil is made of, and the squeeze test will not find either. The hole you dig for the drainage test will — which is the reason to dig a spade and a half deep rather than a spade, and to look at the side of the hole rather than only at the bottom.

Where to take the sample from

Soil varies over a few metres, and more so in a garden that has been built on, levelled or had a pond filled in. Take samples from several places in the bed you actually care about rather than one from the middle of the lawn, and take them from about 10 cm down — the surface is compost, leaf litter and whatever was last spread on it.

Test when the soil is moist rather than saturated or baked. A sodden sample rolls into a ring whatever it is made of, and a bone-dry one crumbles whatever it is made of, so both give a texture reading that is really a moisture reading.

Do not test soil within a few months of liming it, and do not test near a wall, a path or a building — buried mortar and concrete raise the pH locally, which is why a bed against a house so often reads more alkaline than the rest of the garden.

Described viewA vertical soil profile in a freshly dug hole, showing the darker topsoil layer, a change of colour beneath it, and roots turning sideways where they meet a compacted layerRoots turning sideways in a flat plane is the clearest sign of a compaction pan there is.

What to do with the answer

Read the page for your soil: it lists what already grows well there without changing anything, which is the cheapest gain available and the one most often skipped. All eight soils are here.

Only then consider improving it. The interventions page states what each one will and will not change, which decides whether it is worth starting.