Soils and Your Garden
Knowing your soil type is an important step in helping you select plants for your garden. Plants that are suited to your soil type will perform better, be healthier, resist diseases, will flower stronger and produce more fruit.
The two major soil types in the Sydney region are sandy soils, derived from Hawkesbury sandstone, and clay soils, derived from shales and volcanic rocks. Some soils may be a combination of the two.
Some plant species will only grow well in one of the two soil types, while other plants are adaptable and will grow in both.
There are a number of tests that can be done to determine soil types. pH (acidity/alkalinity) and levels of nutrients in your soil. However soil testing is not usually necessary for the home gardener and can be quite expensive.
If your garden is not quite flourishing there can be many possible causes. Problems with water drainage, aspect and suitability of the plants selected are common problem areas.
Further information can be obtained from horticultural reference books or from experienced nursery staff.
Improving Your Soil
Sandy soils are fast draining with good aeration, but are usually low in nutrients. They can be improved by adding well-rotted organic matter such as animal manure, compost or leaf litter. They require more fertiliser more often compared to clay soils.
By contrast, clay soils are slow draining and have poor aeration. They are usually higher in nutrients than sandy soils and can be improved by adding gypsum and well-rotted organic matter. Correct cultivation techniques will also assist in improving soil structure. However, if the soil is too wet or too dry when cultivated, or is always cultivated to the same depth, drainage problems may arise.