Understanding Your Garden’s Soil Type

Understanding your garden’s soil type is essential to growing healthy tomatoes, as soil type determines how much nutrients your plant has access to.

Different soil types have different pH levels, and different pH levels represent the availability of certain nutrients. Understanding the nutrient content of your soil will help you regulate organic matter and fertiliser, and ensure your tomato plant has all the nutrients it requires to flourish.

What is pH?

The term pH refers to whether a solution, or in this case your soil, is acid or alkaline. The pH scale runs from 0 to 14, 7 being neutral. Numbers above 7 indicate alkalinity, and numbers below 7 indicate acidity. Tomatoes do best in a slightly acidic soil with a pH between 5.5 and 6.8.

Soil pH affects the availability of nutrients in soil. We have a helpful chart in our book How To Grow Juicy Tasty Tomatoes that shows the availability of different nutrients at different pH levels.

Testing and Adjusting pH Levels

Litmus paper for testing
pH levels
Image Credit: Cottonwood

To test the pH level of your soil, mix a sample of soil with water and use one of the following:

• A pH metre
• A swimming pool testing kit
• Litmus paper

You can adjust the pH level to suit the fruit or vegetable you wish to grow. If you have extremely acidic soil, and you wish to grow tomatoes, adding lime to your soil is a great option. Adding acidity to the soil (i.e. making the pH level lower) is more difficult, but can usually be achieved with sulphate-based fertilisers, such as sulphate of ammonia.

Soil Type

Now that you know the pH level of your soil, let’s take a look at soil type. Soil type will determine how much nutrients your soil can hold, and how much fertiliser you’ll need to add.

Sandy soils, for example, hold very little nutrients. You will need to add fertiliser every one or two weeks. Clay soils, on the other hand,retain nutrients so don’t require as much additional fertilisers as sandy soils do.

The best kind of soil is friable soil, rich in organic matter.

But this is just the tip of the iceberg when it comes to soil types and preparation.

We have much more to share on soil type, soil condition, soil preparation, fertilisers, location and more in our comprehensive best-selling guide, How To Grow Juicy Tasty Tomatoes. Get your copy now.