Best Way to Understand the Soil in Your Garden

While almost all soils can be improved to make them suitable for growing vegetables, you need to know what type of soil you have to start with.


To find out more about your soil, simply dig a couple of holes in the ground and look at the soil that comes up. Are there a lot of stones or lumps of chalk? Is it baked rock hard? Or is it like dust?

Garden soil 1 Best Way to Understand the Soil in Your Garden

Take up a handful of soil from about 10-15cm down. Squeeze the soil in your hand: if it feels spongy, a bit like compost, it has a high organic content. Rub some soil between your fingertips – a gritty texture indicates that sand is present, while a smooth texture points to a loam or clay soil. Knead the soil in your hands – can you work it into a ball? A soil that cannot be moulded in this way and keeps breaking up contains very few clay particles. The ideal gardening soil is loam, which is a mixture of sand and clay particles. It can hold moisture in summer, yet water can drain through in winter. Where there is a high proportion of clay you can have problems with waterlogging. Try rolling the ball of soil into a sausage shape, then bending it into a circle in your hand; a loam does not have enough clay to make a circle but a soil rich in clay does.


Dig a hole 45cm square and 45cm deep in late winter. Fill it halfway up with water and put on a waterproof cover. Check the level of water in the hole after an hour and again the next day. If the water has disappeared within an hour, it is free-draining soil, but if it is still there the next day, the soil is wet or waterlogged.

Acid or alkaline?

A simple pH test that you can do yourself will tell you within a couple of minutes whether your soil is acid or alkaline. Gardening Which? trials found that the chemical kits for testing pH were better than pH meters available to gardeners. Gardening Which? offers a full soil-testing service for members.

Understand the Soil Best Way to Understand the Soil in Your Garden

Taking a soil sample

Soil tests are done in test tubes so the samples tested are a tiny proportion of the total soil you want to know about. For that reason, it is vital to get a soil sample that is accurately representative. Large areas are best divided into sections which are individually tested.

  • Lay out four bamboo canes in a W-shape across the area.
  • Using a clean trowel, dig down to about 15cm.
  • Take out some soil at the end of each cane (five samples in total).
  • Remove stones, weed roots etc. Mix the five portions together in a clean bucket. Take out the amount needed for the test (usually 500g for a full analysis).
  • To test the soil for pH yourself, take a half-teaspoon of soil and drop it into the test tube of chemical supplied. Add water and shake well. Check the color of the liquid against the color chart supplied.

You should test the pH of your garden soil every two to three years. On the pH scale, 7.0 is neutral, a higher figure is alkaline and a lower one acid.

Garden soil 2 Best Way to Understand the Soil in Your Garden

Most vegetables prefer a pH within the range pH 6.5-7.5, with brassicas preferring the upper end.

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