How to test and adjust your soil pH level

Knowing your soil pH level is essential to growing healthy plants in your garden. Here’s how to make sure you get it right.

Why it is important to know your soil's pH level

The pH level is a measure of acidity that is represented by a value between 0 and 14. Acidic soil has a pH value below 7.0 and alkaline soil has a value above 7.0. Different plants thrive in different soil conditions, and because soil provides many of the nutrients and minerals that plants need, getting the right pH level is important. The wrong pH level will mean that your plants may become nutrient deficient and struggle to grow.

When to test your soil

It’s a good idea to test the pH level of your soil before designing or planting a new garden, creating a vegetable plot or planting varieties of fruit. You should also test when you are disappointed in the growth of your garden or some foliage is starting to show evidence of yellowing. You may even want to consider testing your soil in a few different parts of your garden. You’d be surprised how much the pH levels can vary.

Another thing to note is that if you’ve already added lime, fertiliser or organic matter to your soil recently, you’ll need to wait three months before you get an accurate reading.

How to test for soil pH

To test your soil pH level, a simple and effective way is to use a home testing kit. A good tip when taking soil samples from your soil is to get a sample from just below the surface for an accurate reading.

Another way to test for the pH level is by using an electronic pH meter. They come with a probe that is inserted into the soil that quickly gives you an accurate reading.

Adjusting and balancing alkaline soil pH

After testing your soil, if you have a pH value over 7.0, it indicates you have alkaline soil. This will mean that your soil is low on nutrients like phosphorus, iron and manganese.

To increase the acidity in your soil, you can add things like compost and manure, leaf matter or clippings from your garden or mulch. However, make sure you avoid using mushroom compost and poultry manures as these will drastically increase the alkalinity. A powdered sulphur may be needed to help if the pH reading is excessively high.

Some vegetables like a slightly alkaline soil with a value between 7.0 and 8.0. These include asparagus, Brussels sprouts, cabbage, grapevines, leeks and turnips.

Adjusting and balancing acidic soil pH

If your soil has a pH value below 7.0, it is acidic, which is the case with most Australian soils. This may be a problem as many soil nutrients become more soluble under these conditions and can be easily washed away by rain or watering. Nutrients you may lose include calcium, potassium, magnesium and copper. Another thing to note is that in very acidic soil, bacteria can rot organic matter resulting in plant damage. The easiest way to balance acidic soil is to add lime, dolomite or poultry manure.

There are many vegetables and fruits that will thrive in acidic soil with a pH value below 7.0. These include blueberries, beans, broccoli, beets, garlic, kale, lettuce, peas, potatoes, onions and spinach.

Other great garden ideas

We’ve got plenty of easy D.I.Y. projects, tips and ideas for any size garden.

sprinkler

Planting & Growing How to take care of your plants in summer With its combination of hot and dry weather, summer can be really tough on your garden.

Worm farm

Planting & Growing How to make a worm farm A worm farm can turn your organic waste into rich fertiliser to feed your garden. It’s also a fun and rewarding way to get the kids actively involved in the environment.

Six plants that repel mosquitoes and flies

Planting & Growing Six plants that repel mosquitoes and flies Using plants is a natural and effective way to repel mosquitoes, flies and other insects from entering your home. Here’s a list of the six best insect-repelling plants.

protein

Planting & Growing 10 high protein foods you can grow at home Grow these high protein vegetables and protein rich foods at home in your very own garden. Whether you’re a vegetarian or are trying to eat healthier, here’s our list of top 10 high protein vegetables to grow at home.

Five reasons to plant a mature or advanced tree

Planting & Growing Five reasons to plant a mature or advanced tree Planting a mature or old tree in your garden can be a quick and easy way to create the backyard of your dreams. Here's a few good reasons why planting a mature tree might be worth considering for your garden.

A bee on a flower

Planting & Growing How to attract bees and butterflies Unfortunately, bees, butterflies and other beneficial insects are under increasing threat due to pesticides, parasites and climate change. We can help them by using responsible gardening practices, planting flowers and providing them with shelter.

How to control and eliminate garden pests organically

Planting & Growing How to control and eliminate garden pests organically Try controlling garden pests with these approaches from Eco Organic Garden.

Person putting on protective edging on the raised garden bed 01:38

Planting & Growing How to build a raised garden bed Building a raised garden bed is a simple project you can do yourself. Learn how to build a raised garden bed with this guide from Bunnings Warehouse.

Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.
Top of the content