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What's With Nature And Gardening Potting Mixes


August 1, 2022


Searles Gardening Team

Finding mould and the presence of pesky insects in potted displays can be quite disconcerting. We explain why they proliferate in potting mixes and how to successfully treat them.

Potting mixes are developed from taking recycled organic material and refining the ingredients into a potting mix to grow exceptional plants. Potting mixes are manufactured in large stockpiles which during the composting and maturation process can take up to 16 weeks from start to when it is bagged.

During this process, the temperatures within the vast stockpiles reach levels that eradicate unwanted insects, larvae, and seeds and at the same time produces rich organic matter suitable for growing healthy plants. By the time the potting mix is bagged and ready to ship to our customers, it is in prime condition to grow beautiful plants!

However, once the potting mix is processed and bagged, there may be elements of nature and our localised ecology that enjoy a rich organic potting mix, isolated from predators and generally kept in nice moist conditions. These elements may include gnats, insect larvae and even mould.

In the circumstances of insects, during summer months these insects seek places to lay their eggs and pot plants and bags of potting mixes can be a prime target. The beetle’s larvae grow into curl style grubs which, uncontrolled can infest existing pot plants, soils, gardens and, at times, even gain access to bags of potting mixes. A simple breather hole in bags of potting mixes is all they need to gain access to a space to occupy their young.

Potting mixes do not contain insecticides or other chemicals to treat these various insurgents; which is understandable. No manufacturing process can stop the beetles from laying eggs in pots or bags when they are exposed to such insects. These insects and other components of our local ecology are natural and part of gardening but thankfully, there are various ways to tackle the issues.

In the circumstances that your pots and/or bags of potting mixes contain some curl grubs, you can tackle the problem organically by removing the visual grubs by hand or there are granular insecticides (ask your local gardening outlet for more information) which can easily be applied to pots and gardens to eradicate them.

For gnats, they too love high-quality potting mixes as much as plants do sometimes, particularly indoors, free from most predators in a nice environment which is generally warm. There are a number of ways to tackle these insects. Due to their short life cycle, making the mix less hospitable to them will help dramatically. This can be done by reducing watering and/or applying some low toxicity insecticide will have them beaten quickly. Even covering the exposed potting mix in the pot with small pebbles will help! Removing excess drainage water from pot saucers will assist too. Head to your nearest gardening outlet to learn more about what can be done and how to keep them at bay.

During the warm, humid months of summer, mould can be present in potting mixes, garden soils and generally everywhere in nature. Mould in potting mixes is common with composting organic material and in most cases highly beneficial to the plants. If the mix is a bit mouldy, simply agitate the mix, let it dry out a little and in a couple of days most of it will be gone. There is no need for any chemical treatment to eradicate. Importantly, remember to use personal protective equipment such as gloves and face mask and follow the direction on the bag.

Gardening, pot plants and potting mix are one part of the natural world and your local ecology. As such, all insects, good and bad for your plants, will be present. Gardeners need to keep vigilant on their treasured plants to mitigate any damage. Most of the time their impacts are only very slight and dealt with easily.

There are some easy steps to store and use potting mixes for pot plants to limit the access of these troublesome insects:

  • Store unused portions securely and preferably in sealed containers
  • Upon opening the bag and wearing correct gardening protective equipment, inspect the contents. If necessary, remove any unwanted insects or grubs – ideally pour into a wheelbarrow making it easier to search
  • Don’t leave bags lying around, exposed to the elements – they form excellent homes for insects and their young to avoid their predators
  • Don’t overwater indoor plants. If potting mix is already moist, it doesn’t need more water yet. Remove excess drained water from pot saucers.
  • Keep regular checks on pot plants, particularly in the warmer months – if any insect issues, attend to them quickly
  • Ask your local gardening outlets for great local advice on how to mitigate these natural problems.

The great news is that the potting mix is developed to grow outstanding plants. Once you’ve dealt with any detrimental insects nature may have dished up, you can watch your plants flourish and enjoy the gardening experience with all its great benefits.