CHOOSING A POTTING MIX

In the 1960’s there was no such thing as a ‘potting mix’. Back then nurseries made a ‘soil mix’ with what was available and it had to be modified to suit the plant. Because they were made from soil, they were heavy and there was no standard manufacturing recipe.
Today we use soilless ‘potting mixes’ made from composted organic material which is formulated to an Australian Standard (AS3743). The Standard is a two-tier system of ticks. Black ticks indicate a regular formulation and Red ticks a Premium formulation. Both have to pass stringent tests to be able to carry the Australian Standard Mark 5 Ticks, a photo of which is below. Black ticks indicate that the mix will need added fertiliser and is usually used for annuals, while red ticks indicate the addition of fertiliser and is used for long-term container plants.
The buyer should be aware that there are mixes on the market that do not carry the Australian Standard ticks but have a group of red ticks that mean nothing and the potting mix will likewise grow nothing. The old adage ‘You pay for what you get’ applies.
There is a lot more to growing plants than buying a good quality potting mix. Consideration has to be given to the plant’s needs. It does not make much sense trying to grow a rainforest tree in a Cactus Mix or a Cactus in a moisture retaining mix. So you have to try to understand the plant’s natural environment and try to duplicate it. Some plants will accept a very loose definition of their natural environment and grow happily while others insist on you getting it right from the germination stage through to being a mature plant. These are some of the things that make a ‘good’ gardener.
Happy gardening,
Grahame