Soil pH made simple.

The birds are singing thier little hearts out, the garden is sprouting, and the spring equinox arrived, so it’s official.

I took the photos of these beautiful crocus last week, sadly they’re not in my garden, but they remind me that a simple drift of crocus and a sprinkling of cyclamen is a lovely thing, and I must plant some this autumn.

I had little wander around my garden this weekend, soaking it all in and tweaking the plant list in my head, having been particularly inspired by the Wisley Plant Fair on Friday.

The garden we have now has completely different conditions to our last one, more light and generally better soil …. though some of it is very soggy.

I haven’t tested the soil to check the pH, but my favourite Rhododendron is growing here, and there are camellias and rhododendrons in neighbouring gardens, so it’s a safe bet that it’s on the acidic side.

I would love to get hold of one of these lovely camellias I saw at Great Dixter last year …. I know I have the name somewhere.

Most plants are tolerant of a wide variety of soils, but azaleas, rhododendrons, camellias and blueberrries need soil that’s acidic. Certain vital nutrients remain locked up and unavailable to them if they’re planted in an alkaline soil, their leaves turn yellow and they just don’t grow well.

If you have alkaline soil and want to grow acid loving plants, choose small varieties and plant them in a big pot with ericaceous soil.

If you’re flummoxed by the whole soil pH thing, here’s a little outline:

• The pH of a soil is measured on a scale of 0 – 14
• alkaline soil has a pH above 7
• whilst acid has one below 7

There are various types of soil-testing kits available and it’s a good idea to test soil in a new garden or allotment, before you start buying plants and sowing seeds. The test is simple, add soil to the test-tube, mix in the liquid, the contents change colour and you match the shade to a colour chart. It’s a good idea to take 3-4 soil samples from different areas of the garden, because it can vary, even in a small garden.

Lime can be added to the soil to make it less acidic, but its much more tricky to make soil less alkaline by reducing the pH.

On the whole it’s a time-consuming battle, the soil needs treating every year and testing to check if the adjustments have worked….. easier to go with the flow and choose plants that like the type of soil that you have.

It’s not all bad news, Ceanothus, Clematis and geraniums grow happily in alkaline soil and having some limitations on what you can grow simplifies the choice.

Tell me about your garden, have you tested the soil and used the info. to choose plants or are you leaving it to pot-luck?

Jill

all photos: Jill Anderson