When selecting plants for your garden, you likely consider factors like sunlight, shade, wind, and salt exposure, along with the ongoing maintenance needed to keep them thriving. However, one crucial element that often gets overlooked but should be at the top of your list is soil quality. Understanding your soil is key to ensuring your plants not only survive but truly flourish.
Having a healthy soil is like having a healthy diet, it will sustain your plants and allow them to perform to the best of their ability. Understanding your soil will mean you can select the right plants, lessening your maintenance obligations and improving your soil will allow you to grow a wider range of species.
There are lots of different types of soil, but the main components are sand, clay and loam with “soil” being made up of a combination of all three and each element has benefits and draw backs. The majority of WA soils are sand heavy, and these have the largest particles and as such are very free draining, which is great for so many types of plants, the drawback is obvious with a lack of moisture holding capacity, but this also comes with a lack of nutrient holding capacity. Fertilisers are not a suitable way to replace these nutrients as although very useful to boost growth not a long-term way to feed your plants. If the soil is equivalent to a balanced diet think of fertilisers as vitamins and supplements, they are great at optimising growth but cannot be the base blocks for life.
Clay heavy soils are the opposite; their particles are very small so it holds onto water and nutrients which for some plants is great but for the majority will suffocate the roots and kill your plants. Loam is the goldilocks of soils, a mixture of the two with all the benefits and none of the drawbacks, sadly there are very few locations along the Australian coastline, especially on the west coast, where true loam soil exists.
Improving your soil is something every gardener should do even if you have a good soil and as a rule of thumb the fix is the same for every soil type – compost. Compost and organic matter such as rotted manures help to bind sandy soils together increasing their water and nutrient holding capacity. Whilst the rate is less, adding compost to clay soils helps to bring in worms and micro-organisms that break the clay up increasing air and water flow.
As well as the elements that make up your soil you need to look at the soils structure to get the best out of it. The structure is made up of ‘peds’ which refers to the size of the clumps in the soil, a good soil will have a combination of sizes for air, water and nutrients to all be in perfect balance. Clay soil can often become unstable where it forms one massive ped and the application of compost only makes this worse so if this is the case then an application of gypsum will help break it up and increase the number of peds.
Too much organic matter in sandy soils can lead to hydrophobia which can be treated with a wetting agent that will allow the water back into the soil. Too much fresh compost and organic matter can burn the roots of your plants too so always use aged manures.
Research is showing that the best way to apply these forms of organic matter is to use them as a mulch in the cooler months, they get incorporated into the sub soil by worms and other soil dwelling animals. Why not dig it in, in a traditional manner? Well, the research shows that over time this pulverises the soil structure turning it to dust rather than a combination of peds. Of course digging it through a planting hole and subsequent back fill for individual plants is still a great way to localise an application of organic matter to the soil.
