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- Armchair gardening this week and its water and salinity and what to do about it.
- We garden in a Mediterranean climate here, which has some unique peculiarities. For
instance rain that falls in winter and little in the warm summer, when most plants want to
grow. So in our climate plants have to make the bulk of their growth in autumn and spring
unless you supplement water in summer. The reticulated water you are likely to use is
already loaded with salt of at least 700 parts per million so the more water you add the
more saline your soil becomes, due to its inherent clay structure.
- That is unless you mulch. Which is why Adelaide gardeners are obsessive about the
benefits of mulching their flowerbeds and vegetable gardens in summer. It reduces water
use, by cutting evaporation, creates less salt toxicity to your plants and provides a cool
root run. However most mulch has almost no nutrient value whatsoever. So don’t think
mulch is nutrient.
- Now given all that, the fertilizers that you use to feed your bedding plants and
vegetables, become more critical than if you were to garden in Melbourne or Sydney.
Water-soluble fertilizers leave salt residues in the clay soils in this region that
elsewhere would not be a problem. Now you can either add lots of organic material to your
soil to provide a salt stable buffer or use water-soluble fertilizers with specially
formulated nutrients that don’t leave loads of salt residue.
- At the risk of committing horticultural hara-kiri in the market place, commercial
nurseryfolk know and use Vitall® as their water soluble nutrient of choice, because, it
can be applied as a foliar spray as well as in the soil, so less nutrients get tied up in
the soil because of pH extremes, like iron in alkaline soil. Most importantly Vitall® can
be used on all plants including phosphate sensitive plants like our native plants. The
other great benefit is that it does not leave salt residues in the soil, like most other
nutrients sold to home gardeners.
- In this city we only get water to move down the soil profile for six weeks starting next
week, the rest of the year it is evaporating and creating more residual salts in your soil
and in your containers, which cause that tell tale dry leave margin on tips and edges of
your favourite plants. The only reason salt laden water soluble fertilizers are sold in
Adelaide is because they are made for other markets!
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