To carry out a soil test you will need to purchase a soil-testing kit. Always read the instructions, as kits may vary, and do not be tempted to purchase an unnecessarily elaborate kit for a costly electronic device. Divide the garden into small, logical areas, such as front garden, back garden, right side, left side, and from each area take small samples 6 in (13 cm) deep, 6ft (2m) apart, in a diagonal line from corner to corner.
When taking the samples try not to contaminate one with another by using an uncleaned trowel or spade. Also try not to touch the sample with your fingers as this can distort the readings. If more than one sample is being taken ensure that each is clearly labelled for future reference. Individual samples from each specific area are mixed together and a small quantity selected for testing. From this stage the instructions on the individual test kit should be followed.
The result of the test will show up as a colour-coded reading on a colour comparison chart supplied with the kit. The chart will represent the reading as a pH (phosphorus hydrogen) content. A reading of pH 4 to 6 indicates an acid soil, pH 6 to 6.5 is neutral and 7 to 9 is alkaline. Most gardens will fall into the range 5.5 to 8, and readings outside this are extremes.
Neutral is a difficult area to define and as the difference between success and failure is very fine it is prudent to stay on the side of caution when selecting your plants. Never cheat on the reading, whether acid or alkaline, because in the long run the planting of the wrong plant almost always leads to failure.