Acid Queen Or Alkaline Angel? Plants For Every pH

Identifying where your garden soil sits on the pH scale is ground zero when it comes to choosing and growing plants that are happy and healthy, says Hazel Sillver

- Hazel Sillver

SOIL: it may not be the most exciting thing to talk about, but it’s absolutely crucial when it comes to choosing what to plant. You may love roses, but if your soil is extremely acid, roses will not love you back. You might be enchanted by blue poppies, but they will loathe your chalky earth. I learnt this the hard way, planting heather in my first garden at the foot of the South Downs. While alkaline addicts (such as clematis) flourished, those acid-loving heathers sulked and turned yellow.

Cheating nature?

It is possible to alter the pH of your soil. To help you grow plants that don’t have overly deep roots, additives that raise or lower pH can be dug into the soil. And in a new garden, topsoil with the desired pH can be brought in to replace the existing upper layer of soil, or used to create raised beds. But on a large scale, across a mature garden, trying to turn acid into alkaline (or vice versa) can be pointless tail chasing. Far better to embrace the pH you have and grow the plants that thrive in it.

Determining your garden’s pH is the first step to learning how to work with it. The plants in your garden (or those of your neighbours) will give a good indication. If you’re surrounded by rhododendrons, it’s acid; if the lilacs are happy, it’s alkaline. To be sure, use a test kit (cheap and readily available from garden centres) or the RHS soil analysis service (£30 for members). It’s also fun to look at your area’s pH on the UK Soil Observatory map ( ukso.org).

Right plant, right soil

On the pH scale, 5.1-6.0 is an acid paradise for azaleas and camellias, while 6.1-7.0 is mildly acid and the ideal range for most plants (including roses); 7.0 is neutral; and 7.1-8.0 is alkaline, which offers a greater choice of plants than the acid extreme.