How to Test Your Garden Soil
Testing your soil helps you choose plants, improve beds sensibly and avoid adding things your garden does not need. You can learn a great deal with simple observations at home, then use a kit or laboratory test when you need clearer information about pH or nutrients.
Begin by looking at the soil when it is neither frozen nor waterlogged. Take a small handful from several parts of the bed, remove stones and roots, then rub it between your fingers. Sandy soil feels gritty and falls apart readily. Clay soil feels smooth, sticky when wet and can be rolled into a firm ribbon. Loam has a balanced, crumbly feel, while silty soil feels soft and floury. Note whether water sits on the surface, whether the ground cracks in summer, and whether digging is easy. These observations show how the soil behaves, which is often as valuable as knowing a single test result.
Make a simple texture test by collecting equal small samples from five to ten places across one bed. Mix them in a clean bucket so the result represents the whole area rather than one unusual patch. Add a little water and try rolling a walnut-sized piece into a ball. If it will not hold together, it is likely sandy. If it forms a smooth, bendable ribbon, clay is dominant. If it holds briefly but breaks when handled, it may be loamy. Test vegetable beds, lawns and borders separately, because previous cultivation, imported soil and drainage can make neighbouring areas quite different.
Check drainage with a hole about 30 cm deep and wide enough to fill easily. Fill it with water once and allow it to drain, then fill it again and watch how quickly the level falls. Very rapid drainage may indicate sandy ground that dries quickly, while water remaining for many hours can point to compacted or clay-rich soil. Repeat in another part of the garden before drawing conclusions, especially on sloping ground. Do not test immediately after heavy rain. Poor drainage can sometimes be improved with organic matter and careful cultivation, but a persistently wet site may be better suited to moisture-tolerant plants or raised beds.
Use a garden soil pH kit if you want to know whether the soil is acidic, neutral or alkaline. Follow the kit instructions closely and use a mixed sample from the bed rather than soil from one planting hole. Most vegetables and common garden plants grow well in soil around pH 6 to 7, but some plants have different preferences. A result can vary across the garden, particularly near old building rubble, conifers or paths. Test every few years, or before making a major change. Do not add lime or sulphur simply because a neighbour has done so; respond to your own result and the plants you wish to grow.
For a clearer nutrient picture, send a representative sample to a reputable soil-testing service or ask the RHS or a local garden centre about suitable options. A laboratory report may include pH, organic matter and key nutrient levels, together with interpretation. Take samples from the upper 15 cm of cultivated soil, avoiding recently fertilised patches, compost piles and unusual wet spots. Label each sample with the bed and date. Nutrient tests are most useful before creating a new vegetable area, where crops repeatedly struggle, or when you are unsure whether fertiliser is necessary. They cannot replace observing sunlight, drainage, pests and plant health over a season.
Record your findings in a notebook, on a garden plan or in a simple phone note. Include the date, bed, texture, drainage, pH, crops grown and any compost or fertiliser added. This turns a one-off test into useful evidence over several seasons. Improve soil gradually with garden compost, leaf mould or well-rotted manure, then reassess rather than attempting dramatic correction. A soil test is a guide, not a judgement: healthy gardens often contain different conditions only a few metres apart. Match plants to the conditions where practical, and make changes one bed at a time so you can see what helps.
Frequently asked questions
When is the best time to test garden soil?
Spring or autumn is convenient because the soil is usually workable and you have time to plan improvements. Avoid testing straight after fertilising, liming or adding large amounts of compost, as this can distort a result. For comparison, test similar beds at roughly the same time of year each time.
Do I need a laboratory test for every bed?
No. Start with observation and a home pH kit for ordinary beds. A laboratory test is most worthwhile for a new vegetable plot, recurring unexplained problems or a large area where amendments could be costly. Group beds with similar history and soil together, but sample unusual patches separately.
Can I test soil after heavy rain?
Wait until the soil has drained and is moist rather than sticky or saturated. Wet samples are harder to collect consistently, and a drainage test made immediately after heavy rain tells you less about normal conditions. If your garden remains wet for a long period, record that as useful information.
General guidance for UK home gardens and allotments. Conditions vary by region, soil and season; the RHS or a local garden centre can give site-specific advice. Page updated 19 Sep 2026.