Now you may be expecting me to talk about low maintenance plants, efficient water use, maybe even ground breaking landscaping practices – but I’m not. Quite simply none of that matters, unless you get the most important crux of all your gardens success right. What I’m talking about is soil.
And nowhere is creating good soil more important than right here in Perth. Every day as I drive around town quoting and managing jobs I see hundreds of gardens absolutely struggling – lawns yellow and full of weeds and garden beds filled with sickly looking plants.
Listen in closely. You’re missing the most crucial key to gardening success. You’ve likely never been told about it, everyone’s heard about mulch, water wise irrigation and planting the right plants. But almost no one talks about soil texture.
Water repellent, dry dusty SAND. That’s your problem. The fix is easy though, when you know some basic soil science. Here in Perth we have just that – SAND. Our “soil” has no clay or silt, and because of that all of the precious organic matter we keep adding just blows away in the wind. There is nothing there to hold onto it – no silts or clays.
Thankfully sand is the easiest of soils to work with. It’s much easier to add clay and silt to sand than it is sand to clay based soils. Another great thing about sandy soils is that because they are so loose, they almost never have any excesses – with the exception of calcium, if the soil has limestone in it; or sodium if the water we are irrigating with is salty, which most of our older Perth bores are.
Being so open and leachable isn’t a good thing though because ALL of the nutrients are leeched out of the soil, not just the excesses. Which means we need more fertiliser and our plants need more specialised care.
Clay, clay, clay! Add it to your sandy garden soils. The best clay I’ve used is Kaolin clay, followed closely by its very similar cousin bentonite. Both clays will permanently change your sandy soil to dark rich loams that will build in fertility year upon year - without much input from you.
The best builders of soils are plants, a story for another article. But you need to start the process by balancing your soil first and foremost with the correct amount of clays and silts.
For vegetable gardens and tropical gardens which have plants that demand deeply fertile soils I recommend mixing in 10-15kg of clay per m2 – don’t go over 25kg though, or you’ll end up with gluggy, wet clayey soil.
For Mediterranean and exotic gardens (roses, perennials etc) aim for 7-10kg per m2. And for native gardens adding just 5-7kg per m2 will be enough to change your water repellent dusty soils into free draining, water absorbent goldmines for natives.
Mix the ratio you choose into the top 30cm of the soil for new garden beds or rake it into the top 15cm of soil around plants in established gardens. Remember to always water the soil to help the clay bind to the sand and organic matter – this will jump start the soil building process.
Finish the project with a 100-150mm layer of course wood chip mulch and within 6 months you’ll have the richest soil in Perth. You can then grow anything to your heart’s desire without a worry.