Potting Mix: A Complete Guide to Choosing the Right Mix for Potted Plants

Choosing the right potting mix can make a big difference to how well plants grow in containers. Unlike plants growing directly in the garden, potted plants rely almost entirely on the growing medium inside their container for moisture, air and access to nutrients.

But walk into a garden centre and the choices can quickly become confusing. Premium potting mix, native mix, succulent mix, orchid mix, seed-raising mix — which one do you actually need?

The good news is that you don't need to be a horticultural expert. Understanding a few basic differences can help you choose a potting mix that suits both your plant and the conditions where it will grow.

For more general advice on caring for plants in containers, visit our complete Plant Pot Garden guide.

What Is Potting Mix?

Potting mix is a growing medium designed specifically for plants grown in containers.

Depending on the product, it can contain materials such as composted bark, coir, sand, perlite, compost and added nutrients.

A good potting mix needs to do several jobs at once. It should:

• hold enough moisture for the plant
• allow excess water to drain
• provide air around the roots
• physically support the plant
• provide or hold nutrients

This balance is important because plant roots need both water and oxygen. If a mix remains too wet and compacted, there may not be enough air around the root system.

Gardening Australia recommends looking for potting mixes that meet the Australian Standard. It explains that black ticks indicate a basic standard mix, while red ticks identify a premium mix containing added fertiliser and sometimes other additions such as wetting agents.

Potting Soil and Potting Mix: What's the Difference?

You may see the terms potting soil and potting mix used interchangeably online, particularly on overseas gardening websites.

In Australia, potting mix is the more common term for commercially prepared growing media used in containers.

Despite the name, many potting mixes contain little or no actual garden soil. Instead, they're made from a combination of materials chosen to create the right balance of drainage, moisture retention and aeration.

Garden soil behaves differently when placed inside a container. It can become heavy or compacted and may not provide the same drainage and airflow as a purpose-made potting mix.

For most everyday container gardening, using a product designed specifically for pots is the simplest place to start.

What Is Potting Mix Made From?

There isn't one universal recipe.

Different manufacturers and speciality mixes use different ingredients, but you may find materials such as:

• Composted bark – adds structure and organic material.
• Coir or other moisture-retaining materials – can help the mix retain moisture.
• Perlite – lightweight particles commonly added to improve drainage and aeration.
• Sand – often found in free-draining mixes.
• Compost or organic material – can contribute nutrients and moisture retention.

Fertiliser – some mixes contain added nutrients to help plants establish and grow.

Gardening Australia notes that different plant types benefit from different combinations. For example, some indoor plants benefit from additional perlite for aeration, while succulent mixes are generally designed to drain more quickly.

How Do You Choose the Right Potting Mix?

Start with the plant.

A general-purpose potting mix can suit a wide range of common potted plants, but some plants have more specialised needs.

Indoor Plants

Many indoor plants need a mix that provides good drainage while still retaining enough moisture to prevent the roots drying too quickly.

Succulents and Cacti

Succulents generally prefer a free-draining growing medium because many are adapted to drier conditions.

We'll cover this in more detail in our upcoming guide to the best potting mix for succulents.

Orchids

Many orchids don't grow naturally in ordinary soil, so they often require a much chunkier, highly aerated growing medium.

This deserves its own guide because orchid potting mix behaves very differently from a standard general-purpose mix.

Australian Native Plants

Some Australian natives, particularly plants in the Proteaceae family such as grevilleas and banksias, can be sensitive to high phosphorus levels. Gardening Australia recommends choosing a suitable low-phosphorus native mix for these plants.

Always check the requirements of the particular plant rather than assuming one bag will suit everything.

Can You Mix Potting Soil or Potting Mix Yourself?

Yes, gardeners often customise commercial potting mix to better suit particular plants.

If you're learning how to mix potting soil or potting mix, it can be simpler to begin with a good-quality commercial mix and adjust it rather than creating a growing medium entirely from scratch.

For example, gardeners might add materials to:

• increase drainage
• improve aeration
• retain more moisture
• add organic matter
• provide additional nutrients

Gardening Australia demonstrates adjusting a base potting mix with ingredients including perlite, bark, compost, sand and other materials depending on what is being grown.

We'll explore this in more detail in our separate guide to how to mix potting soil for potted plants.

How Does Potting Mix Affect Watering?

Potting mix and watering are closely connected.

A very free-draining mix may dry quickly, while a mix that holds more moisture can stay wet for considerably longer.

This means two identical plants in different potting mixes may not need watering at the same time.

Rather than watering automatically on a fixed schedule, check the condition of the growing medium first. Our guide to how often you should water plants in pots explains this in more detail.

How Often Should You Replace Potting Mix?

Potting mix doesn't remain exactly the same forever.

Over time, organic materials can break down, the mix can become compacted and the plant's roots may eventually fill much of the available space.

When repotting, adding fresh mix can help restore structure and provide the plant with a better growing environment.

How often this is needed depends on the plant, the pot, the growing conditions and the type of mix being used.

Can You Reuse Old Potting Mix?

Sometimes, but use judgement.

Old potting mix may still be suitable for reuse or refreshing if it is in reasonable condition and hasn't been associated with serious pests or disease.

If the mix has become badly compacted, smells unpleasant, drains poorly or was used by a plant with significant disease problems, replacing it may be the safer option.

Choosing Potting Mix Starts With the Plant

There isn't one best potting mix for every plant.

The right choice depends on what you're growing and how much drainage, moisture and aeration that plant prefers. Start with a quality mix designed for container growing, check whether your plant has any specialised requirements, and adjust your approach as you learn how the plant responds.

If you're planning a particularly large container, remember that the pot itself, plant, potting mix and retained water all contribute to the finished weight. Our guide to large garden pot plants covers some of the other factors worth considering before planting.

For large or heavy potted plants that need to be repositioned for sunlight, watering or everyday care, Plant Glider sits discreetly underneath compatible pots and provides 360° movement. Always consider the final weight, size and stability of your planted container when choosing a suitable Plant Glider.

Gardening Information Disclaimer

The information in this article is general in nature and is provided for gardening information and inspiration only. Plant care requirements can vary depending on plant species, climate, location, potting mix and individual growing conditions. Plant Glider does not provide professional horticultural advice.

For advice specific to your plants or local growing conditions, consult a qualified horticulturist, reputable local nursery, Gardeners World or another recognised Australian gardening and horticultural resource.

Always follow manufacturer instructions and relevant local guidance when using fertilisers, pesticides, fungicides or other garden treatments.