As gardeners, we all know about acid loving plants like rhododendrons, azaleas and camellias, along with others like Japanese maples even daffodils and magnolias. But why do these plants prefer acidic soils, whereas other such as geraniums, poppies and the cabbage family prefer alkaline soils?
It really boils down to one major factor of evolution, which is driven by nutrient availability. This is then influenced by soil pH (ie: acid or alkaline loving plants). If you look at the soil from which these plants originated from, you can soon see that this is the driving force behind their nutrient requirements.
We can take our native plants as an example, such as the phosphate-sensitive plants in the Western corner of WA. These have evolved to take up phosphate when it is present in very low amounts, so when they are given too much, they suffer badly. Similarly, plants that love acid soils have the same issue.
So what is the under lying reason for this?
In order for plants to take up nutrients, the membrane of the roots contain small biological pumps – their number and efficiency varies between different species. In acidic soils, certain nutrients are more available such as iron, manganese, boron, zinc and copper, so plants that love acidic soil have either fewer or less efficient pumps because they don’t need them.
When you put a plant like this into a soil type where these nutrients are tied up or not available, the plants can’t access the nutrients at a level they require, so they suffer. The opposite occurs in these phosphate-sensitive natives – their pumps for phosphate are so efficient and can’t be switched off that they then suffer from phosphate toxicity.
In order to overcome this issue of nutrient limitation for acid loving plants, Neutrog have developed a product called Kahoona, which is enriched with iron, boron, molybdenum and zinc. This means that even if these nutrients are normally locked up in your soil, you can still feed them to your plant through this product. We have even dropped down the level of phosphate in Kahoona, as acid loving plants in neutral to alkaline soils can suffer from phosphate sensitivity.
So Kahoona allows you to grow those wonderful flowering plants like your azaleas, rhododendrons, camellias and even blueberries in less than ideal soils. Producing a fertiliser is not only about throwing nutrients together – it’s also about understanding how and why certain plants have different requirements.
Following successful trials, Kahoona is endorsed by Camellias South Australia, the Australian Rhododendron Society (SA Branch), the Camellia Society of WA, Camellias WA, Camellias Illawarra and the NSW Camellia Research Society.
Kahoona is available from Bunnings, Mitre 10, Stratco and all good garden centres.