Garden pH

Two common complaints at the ABC Gardener’s Market were ‘my soil pH is too acid’ and ‘my soil pH is too alkaline’. Anyone that grows ornamental or consumable plants should be interested in their soil pH. Too alkaline and plants will struggle for nutrients; too acid and they can both struggle for nutrient and succumb to metal toxicities. Most plants like a pH around 6-7.5, though like all life there are species and varieties that prefer or tolerate different situations.

What can you do about pH?

This is a question that can involve a lot of fluffy answers and ‘it depends’ type scenarios. Not interested in making big changes to your soil? Then use a garden pH test to check a few spots around the place and simply buy plants and varieties that will enjoy what you’ve already got. Remember though, that plants will also have soil texture and light requirements. Get all three mostly right and you should be fine.

Have a sandy soil? You can add compost and/or agricultural lime to make it less acid or add garden sulfur to make it less alkaline. In either case, you’ll need to reapply over time as both lime and sulfur are fairly slow to react.

Have a loamy soil? Do the same as with sand, but you’ll need a lot more and it’ll proceed a fair bit slower.

Have a clay soil? Perhaps the best thing you can do is add as much organic matter (compost, etc.) as possible. Clay soils are beautiful when they’re in good condition and a nightmare when they’re degraded. Compacted clay soils might need some mechanical assistance to get a timely response. That means turning the compost into the soil. It’ll be hard work.

Clay soils are a really good case study for prevention being much easier than cure – stay off them when they’re wet, keep things growing, and add as much compost as possible and they’ll be good to go forever.