Gardening: Picking the right potting mix

Remember the days of filling the base of a pot with the remnants of other broken pots, a handful of gravel or even bits of flyscreen to help improve drainage before you mixed a bit of garden dirt and a handful of compost to create some magical blend to give your plants a good start? Thankfully with years of research and product testing, the potting mixes of today are a ready-to-use bounty of nutrient rich, plant-loving goodness.

What’s in potting mix?

There’s a general misconception that potting mix is dirt, when in fact there’s no dirt in it at all. A good quality mix is a blend of rich organic matter and minerals tailored to suit the plant species it’s created for.

Grains of sand, peat moss, bark, recycled organic material and composted matter such as manures form the base, with additives such as water crystals, zeolite, coir peat and fertilisers to assist with water retention, drainage and both fast-acting and slow-release plant food.

Potting mix is manufactured in large stockpiles taking up to 16 weeks, from start to when it is mature enough, to be bagged.

Selecting the right one

Firstly, look for the ticks! All good quality mixes will feature the Australian Standard ticks of approval. This means they are a certified product, that complies with the Australian guidelines for premium or regular grade potting mixes.

Next… what are you planting? Most packaging will showcase what the mix is to be used for as different plant species have varying requirements. Cacti and succulents need a free-draining mix while ferns love moisture. The mix for an orchid or bromeliad is chunky and bark-based, while herb and vegetable mix is nutrient-rich and friable.‍

Years of research to determine the right blend of core ingredients and additives takes place before a mix is released for sale, so there’s no guess work for you and nothing extra needs to be added.

‍It’s alive!

The composting action required to create a potting mix is based on microbial activity, so while the temperature of these stockpiles reaches a point where it will eradicate unwanted insects, larvae and seeds, it’s also becoming a healthy environment for microbes, essential for plant growth.

It’s also the reason you’ll occasionally find mould or fungus in a mix as the product continues to develop. If the content 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 remove it and always remember to use gloves and face mask.

‍TOP TIPS

• Store unused potting mix securely and preferably in sealed containers in a dry place

• Always open the bag in a well-ventilated area wearing gloves and avoid breathing in the contents

• Look for the Australian Standard ticks on the bag

• If you’re unsure about which mix to use, ask your local garden centre staff