The Ultimate Guide to Garden Soils in Australia: Choosing the Right Soil for Every Plant

Healthy soil is the foundation of every thriving garden. Whether you're growing lush herbs on a sunny balcony or cultivating tomatoes in raised beds, the type of soil you choose has a significant impact on plant health, root development, water retention, and yield.

Most gardening stores in Australia offer a variety of soil types, each designed for specific growing conditions and plant needs. In this guide, we’ll take a deeper look at the most commonly available soils, what they’re made of, their pros and cons, and what plants they’re best for — with special attention to Perth's sandy soil conditions and tailored mixes for tomatoes and basil.

---

1. Potting Mix

What It Is:

Potting mix, often sold as “premium potting mix” in gardening centres, is a soilless growing medium made from a carefully balanced blend of organic and mineral materials. It typically includes:

• Coconut coir or peat moss (for moisture retention)

• Perlite or vermiculite (for drainage and aeration)

• Composted pine bark or green waste

• Controlled-release fertiliser (optional)

• Wetting agents and lime (to balance pH)

Benefits:

• Excellent drainage and airflow

• Sterile and pest-free (ideal for seedlings and indoor plants)

• Lightweight and easy to work with

• Holds moisture while avoiding root rot

Drawbacks:

• May dry out quickly in hot climates if not regularly watered

• Needs replenishment of nutrients over time (especially if no fertiliser is included)

• More expensive than basic garden soil

Best For:

• Potted herbs (basil, parsley, thyme)

• Tomatoes, capsicum, and leafy greens in containers

• Indoor plants and seedlings

Regional Note – Perth:

Potting mix is essential in Perth for container growing, especially since native soil is often too sandy and nutrient-poor. Raised garden beds filled with premium potting mix allow you to bypass local soil issues entirely.

---

2. Garden Soil

What It Is:

Garden soil refers to native topsoil that has often been screened, blended with compost, and sometimes enhanced with sand or fertiliser. It's heavier than potting mix and meant for in-ground planting.

Components can vary, but it often includes:

• Natural loam or sandy loam

• Aged compost or green waste

• Trace minerals or manures

Benefits:

• Higher nutrient levels than some mixes

• Affordable and available in bulk

• Good for improving poor backyard soils

Drawbacks:

• May be too heavy or compact for pots or raised beds

• Inconsistent composition (varies by supplier)

• Can contain weed seeds or pathogens if not well processed

Best For:

• Building or improving garden beds

• Trees, shrubs, and long-term plantings

• Mixing with compost or potting mix for added volume

Regional Note – Sydney, Brisbane:

Garden soil in these regions is often clay-based and may require gypsum or organic matter to improve texture and drainage. Always test the structure before planting.

---

3. Sandy Soil

What It Is:

Sandy soil has large, gritty particles and feels coarse when rubbed between fingers. It drains quickly and warms up fast in spring but is low in nutrients and water-holding capacity.

Natural sandy soils are common in coastal and arid areas like Perth, Geraldton, and parts of South Australia.

Benefits:

• Drains extremely well (great for drought-tolerant plants)

• Easy to work with, even when wet

• Low risk of fungal root diseases

Drawbacks:

• Requires constant watering and fertilising

• Doesn’t retain nutrients — they leach out quickly

• Plants can become heat-stressed without mulch

Best For:

• Mediterranean herbs like rosemary, oregano, and lavender

• Root vegetables (carrots, radishes) if amended properly

• Succulents, cacti, and natives adapted to dry conditions

Regional Note – Perth:

This is the default soil type for many Perth gardeners. It’s critical to add compost, clay, or wetting agents to improve nutrient retention if you plan to grow veggies or herbs in native sandy beds.

---

 4. Clay Soil

What It Is:

Clay soil is made of very fine particles that clump tightly together. It holds water well but drains poorly, making it dense and often sticky when wet. Many inland and hilly suburbs across Hobart, Canberra, and inland Sydney have clay-dominant soils.

Benefits:

• High nutrient-holding capacity (great if improved properly)

• Stable structure for trees and large shrubs

• Good moisture retention in dry periods

Drawbacks:

• Prone to waterlogging and compaction

• Can be hard to dig and work

• Roots may struggle without aeration

Best For:

• Hydrangeas, camellias, and other moisture-loving ornamentals

• Fruit trees (if planted in raised areas or mounded beds)

• Long-term soil-building projects with compost and gypsum

Tip:

Clay soil can be improved significantly over time by adding gypsum, compost, straw mulch, and organic matter. Raised beds are often used to grow vegetables where clay is dominant.

---

5. Loam Soil

What It Is:

Loam is the gold standard of garden soil — a balanced mix of sand, silt, and clay, with plenty of organic matter. It offers the perfect balance between drainage and moisture retention, structure and softness, and nutrient availability.

Many high-end garden soils are marketed as “loamy soil” and sold in bags or bulk for raised beds.

Benefits:

• Holds nutrients and moisture efficiently

• Drains well without becoming compacted

• Ideal texture for most vegetables and herbs

• Easy to amend, plant in, and maintain

Drawbacks:

• Rare to find naturally (often needs to be purchased or blended)

• Premium price point at garden centres

• Needs compost replenishment seasonally

Best For:

• Tomatoes, basil, leafy greens, root crops, and fruiting plants

• Flower beds and mixed ornamental gardens

• Raised bed vegetable gardens

Regional Note – Melbourne and Adelaide:

Some suburbs naturally have loam or silty loam soils, making them excellent locations for diverse planting. Still, seasonal composting and pH balancing are necessary.

---

The Best Soil for Tomatoes and Basil

For Tomatoes:

Tomatoes need rich, well-draining soil that can hold nutrients and moisture without becoming soggy. Look for:

• A vegetable or tomato-specific mix containing compost, perlite, and blood & bone

• Slightly acidic to neutral pH (6.0–6.8)

• Fertiliser that includes phosphorus and potassium (for root and fruit development)

Tip for Perth: Use raised beds filled with vegetable potting mix, or amend native sandy soil with compost, worm castings, and mulch.

For Basil:

Basil prefers slightly lighter soil than tomatoes but still thrives in:

• Premium potting mix or herb-specific mix

• Good drainage and aeration

• Added compost for gentle, steady feeding

Avoid heavy clay or overly dry sand. In containers, make sure pots are deep enough (at least 20 cm) and use mulch to retain moisture.

---

Products to Help You Grow

Need help choosing the right soil or mix for your plants? Browse our website for quality potting mixes, compost, tomato blends, seedling trays, and natural fertilisers. Whether you’re growing chillies in Perth or parsley in Hobart, we’ve got something to help your garden thrive.

---

Final Thoughts

Understanding your soil and choosing the right type for your plants is crucial to gardening success. Whether you're improving sandy soil in Perth, managing clay in Hobart, or creating the perfect loam in Melbourne, investing in the right base will reward you with stronger, healthier, more productive plants.

Keep your eye on our blog for more in-depth guides — next up: composting tips for home gardens and how to build raised beds that suit your climate.