Potting Mix 101

What Should You Look for in a Potting Mix?

• Quality ingredients and a stable structure

• Suitability for the plants you are growing

• Included fertiliser and nutrients

• Effective moisture penetration and retention

• Compliance with the relevant Australian Standard

What Makes a Good Potting Mix?

Choose a Quality Mix

Look for a quality potting mix made for plants grown in containers. These mixes are formulated to provide the balance of drainage, moisture retention, aeration and physical support that healthy roots need.

A mix labelled 'Premium' should provide suitable physical properties and include enough nutrients for initial plant growth. Some product ranges may also use names such as Premium Plus or 'The Best' to identify mixes with additional features, so always check the information on the bag rather than relying on the product name alone.

A cheaper mix is not automatically unsuitable, but it may contain fewer added features or require fertilising at planting. Compare the label carefully so you know what is included and whether anything needs to be added.

Match the Mix to Your Plants

Different plants can have different growing requirements. Some potting mixes are formulated for particular plant groups to provide the appropriate drainage, nutrient balance or growing conditions.

Choose a mix suitable for the plants you want to grow, whether that is vegetables and herbs, fruit and citrus, indoor plants, orchids, succulents or Australian natives. This is particularly important for plants with specialised nutrient or drainage requirements.

Check the Included Fertiliser

Many premium mixes include a controlled release fertiliser that supplies nutrients over a stated period. The feeding period will vary between products, so check the bag to see what is included, how long it is expected to feed and when additional feeding may be required.

Some mixes combine controlled release feeding with organic ingredients, while others may contain little or no added plant food. Always follow the directions on the bag and choose any supplementary plant food according to the needs of the plant.

Look for Moisture Management Ingredients

A good potting mix should absorb water evenly, drain freely and retain enough moisture for plant roots without remaining waterlogged. The exact balance required will depend on the plant and its growing conditions.

Some mixes contain wetting agents to help water penetrate and spread through the mix. Others may also include coir or water-storing crystals to support moisture retention. Check the pack to understand which ingredients are included and how to water the mix correctly.

Check the Australian Standards Mark

Australian Standard AS 3743 covers physical, chemical, biological and labelling requirements for packaged potting mixes. It includes requirements for regular-grade, premium-grade and certain special-purpose mixes.

When comparing products, look for the Australian Standards certification ticks on the bag. Red ticks identify certified premium-grade mixes, while black ticks identify certified regular-grade mixes. A regular-grade mix can still provide an appropriate physical growing medium, but it may require fertiliser to be added at planting.

What About Organic Potting Mix?

For gardeners who prefer organically based products, a 100% natural mix may be an option. However, the terms “natural”, “organic” and “Australian Standards certified” do not mean the same thing.

Check the packaging for recognised certification and make sure the product is suitable for the plants you are growing. An organic claim does not automatically confirm compliance with AS 3743, just as an Australian Standards certification does not automatically mean a mix is certified organic.

Potting Mix Checklist

Before choosing a bag, ask yourself:

• Is the mix suitable for the plants I want to grow?

• Does the bag identify the mix as regular, premium or specialist grade?

• Does it contain plant food, and how long is the feeding period?

• Does it include a wetting agent, coir, water-storing crystals or other moisture management ingredients?

• Does it display the appropriate Australian Standards certification mark?

• Are there any plants or growing situations for which the mix is not recommended?