How to fix soil problems

Many people are quick to blame themselves when they can’t grow plants in their garden. But the problem may be a little deeper – soil deep. Soil is one of the most important elements of a successful plot. It provides your plants with a solid footing and gives them access to water and essential nutrients. So no matter how much you water and fertilise, if the soil is sad, your garden will be, too! There are many different types of soil and some just aren’t cut out for the garden. Read on to find out if you have to ditch your soil or whether you can make a mountain of magnolias out of your molehills.

Problem solved

When the Better Homes and Gardens team found a courtyard, the soil was heavy clay and very alkaline. Half the soil was replaced with a layer of organic matter, with blood and bone compost on top, finished with a layer of improved soil mix. Then the soil was ready for planting! We used assorted shrubs and groundcovers, with the shrubs clipped into interesting shapes to add life to the square enclosure.

Know your soil

1. Test your soil pH
Soil pH testing kits are available at most nurseries and are easy to use. Test the soil in a few spots to get an overall reading. Its pH is a measure of acidity or alkalinity, given on a scale of 1-14, with one being extremely acidic and 14 being extremely alkaline. Most plants will thrive in a neutral environment, with a pH around seven. If your soil is acidic, with a pH range of 4.5-6.5, then most native plants as well as proteas, citrus, azaleas, rhododendrons, camellias and many herbs will grow happily. If your soil is slightly alkaline, with a pH range of 7-8, it will suit most members of the pea family, iris, lilac and lavender.

If your soil is extremely acidic, you can add dolomite to bring the pH level up. If it’s very alkaline, add organic matter and agricultural sulphur to bring the pH down. Use a little at a time – changing soil pH can take a year or more.

2. Check your soil texture
To test your soil, grab a handful and squeeze it into a sausage to see how it holds together. There are three common types of soil:

• Sandy soil is grainy and crumbly, and won’t hold together. It’s typical of many coastal gardens – improve it by adding compost or cow manure, and mix it with a good quality loam.

• Clay loam will hold together well. It has a good combination of both sand and clay, and is the perfect soil for the garden.

• Strongly clay soil will feel sticky and easily forms a firm sausage. You could almost make a sculpture out of it! If it’s light-medium clay, which is soft and malleable, you can improve it by adding organic matter as well as blood and bone compost, and top it off with an improved soil mix. However, if the clay is heavy, very hard to mould and almost plasticine-like, it can be easier to ditch it. Dig out approximately 30cm, add a mix of organic matter and compost, and refill with an improved soil mix.

3. Assess your soil drainage
To check how well your soil drains, dig a couple of holes and fill them with water. If it drains away quickly, you probably have sandy soil and water retention can be an ongoing problem. Mulching and adding water crystals will help. If the water is still there after a few hours, boggy conditions can be a challenge in your garden, so install extra drainage and add organic matter.