Like with any product purchase, when you buy potting mix (or “artificial growing media” as the official name goes), it’s important to compare options carefully and be sure you’re choosing something that suits your goals.
You get what you pay for
The term “you get what you pay for” is used so often that it doesn’t have as much of an impact these days, particularly with so many good-value alternatives on the market now. However, when it comes to potting mix, this is something you really do need to consider.
Whether on TV shows, in magazines or on blogs, most gardening experts recommend choosing premium potting mix to ensure your plants to thrive. There are good reasons to spend a little more.
Quality products (often indicated by ticks of inclusion in the Australian Standards Mark, requiring the passing of many stringent tests) are worthwhile because they have greater water-holding capacity.
This means you spend less time watering. However, they also have a good balance of elements enabling them to drain effectively too, so plant roots get the water they need without drowning.
Top choices also contain extra nitrogen, which may reduce the need for additional fertilisation. Plus, premium mixes typically remain at peak performance for longer. When using the best potting mixes, you should get more and longer-lasting blooms on flowers, plus quicker growth with the herbs and vegetables you house. People who use top products also tend to notice they have less plant loss with seedlings, and better germination rates.
Tips for choosing potting mix
When comparing options, apart from looking for inclusion in standardisation programs (where red-coloured ticks indicate premium product), be on the lookout for potting mixes which are as fresh as possible. The longer mix is in its bag, the more the microorganisms within it will start to consume its nutrients, which dilutes its potency for your plants.
Buy the right type of potting mix for the plants you’re growing, too, of course. Different plants have different needs, so don’t just get a single bag of mix and expect it to work equally well across all of your pots.
In fact, it often pays to buy a specialised potting mix formulated for set purposes and plant types. This is particularly the case when you have a plant that might be a little harder to grow in your area, or just fragile in general. Potting mixes designed for these plants will give them the most suitable conditions for healthy growth.
Be aware that you can’t tell the quality of a potting mix just from how it looks, either. While dark colours are usually associated with top-of-the-line mixes, often cheap potting mixes, which may only be two to three days old, have some Ferrous Sulphate added to blacken the mixture. In this case, the mix is likely to be toxic to your plants, rather than helpful.
On the other hand, good products are composted for two months or so. This additional time allows for the toxic tannins present in the pine bark or sawdust that most mixes are made from to leach out. This makes them safe for plants.
While potting mixes can be made from a number of different materials, including pine bark and sawdust as mentioned, plus also coir, sand, bark chips, peat and peatmoss, perlite, and vermiculite, avoid products which contain soil. Soil isn’t used much in commercial mixes because it is heavier and prone to waterlogging. It may also contain pests, diseases and seeds which you really don’t want to introduce into your pots.
If you feel totally overwhelmed from the choices on offer, ask an expert at your local nursery or other supplier for guidance.