An intriguing way to renovate your garden is to consider playing with existing plantings. The classic example is Hydrangeas, which can change colour in chameleon-like fashion. The colour of hydrangeas varies according to your soil’s pH, with flowers turning blue in acidic soils and pink in alkaline conditions. Whilst there are products with names such as ‘Hydrangea Blueing Tonic’ it is possible to achieve the same result with simple compounds such as aluminium sulphate or iron sulphate, which should be much cheaper. To make the flowers pink (i.e. make your soil more alkaline) simply apply lime or dolomite. Whichever effect you are trying to create, a dose of a couple of dessertspoonfuls sprinkled around the base of the plant and watered in well will get the process started. You may need to repeat the dose depending on the initial pH of the soil, let the hydrangea’s colour be your guide.
Note that some hydrangeas do not change colour with a change in pH. White flowered ones have no pigment so will stay white.