Scoria is one of those garden and landscaping materials that does its best work behind the scenes. You may not notice it once the job is finished, but it can play an important role in drainage projects, especially where water needs somewhere to move.

At HGS Garden Supplies, Scoria 20mm is available through the Screenings & Crushed Rock range. It is listed as a lightweight aggregate suitable for in-ground drainage and behind retaining walls.

That makes it a handy option for landscapers, tradies and homeowners working on practical outdoor projects around Hurstbridge, Gembrook and nearby areas. Whether you are sorting out drainage behind a new retaining wall or planning a landscaping job where water movement matters, Scoria 20mm is worth knowing about.

What Is Scoria Used For?

Scoria is commonly used where drainage is the priority. HGS lists Scoria 20mm as a lightweight aggregate, which makes it suitable for jobs where you need a drainage material rather than a compacted base.

Its main uses at HGS are:

In-ground drainage.

Behind retaining walls.

That is the safest way to think about scoria when planning a project. It is not the same as crushed rock, and it is not usually chosen for the same purpose as decorative pebbles, toppings or compactable driveway materials.

If you are looking for a firm base for paving, road base or driveway preparation, crushed rock may be a better fit. If you are trying to help water move through a drainage zone, Scoria 20mm may be the product to ask about.

Why Drainage Matters in Landscaping

Water can cause plenty of trouble in a garden or landscaping project when it has nowhere to go. After heavy rain, poor drainage can leave areas wet, soft, muddy or slow to dry out. Around retaining walls, trapped water can also increase pressure behind the structure.

Good drainage planning helps move water away from problem areas. This can support better long-term performance for walls, garden edges and landscaped spaces.

Scoria 20mm can be useful because it creates space for water to move through the material. That is why it is commonly considered for drainage zones rather than areas that need tight compaction.

Like most landscaping materials, it works best when it is used for the right purpose. A quick chat with the team at HGS can help you choose the right material before you order a load and start shovelling. Your back will thank you later.

Using Scoria Behind Retaining Walls

One of the most common uses for Scoria 20mm is behind retaining walls. When soil sits directly behind a wall, rainwater can collect in that area. If the wall has not been planned with drainage in mind, that trapped water can create extra pressure.

A drainage aggregate such as Scoria 20mm can help form a zone behind the wall where water can move more freely. This is one part of a broader drainage setup, and the exact approach will depend on the wall, site conditions and project requirements.

For DIY projects, it is important not to guess. Retaining walls can vary a lot depending on height, soil, slope and location. If you are not sure what your wall needs, get proper advice before starting.

For landscapers and tradies, having the right aggregate on site can make the job more efficient. HGS supplies both public and trade customers, so you can order for a small backyard job or a larger landscaping project.

Scoria vs Crushed Rock

Scoria and crushed rock both sit within the broader world of landscaping aggregates, but they are used differently.

Crushed rock is often used when a firm, compactable base is needed. HGS’s Screenings & Crushed Rock range includes crushed rock products used for projects such as paving bases and driveways.

Scoria 20mm, on the other hand, is listed for in-ground drainage and behind retaining walls. It is better understood as a drainage aggregate rather than a base material for hard surfaces.

A simple way to choose is:

Choose scoria when drainage is the main goal.

Choose crushed rock when compaction and base preparation are the main goals.

If a project involves both a hard surface and drainage, you may need more than one material. For example, a path area may require a compacted base, while a nearby retaining wall may need drainage material behind it.

When Should You Ask About Scoria?

Scoria may be worth asking about if your project includes:

A retaining wall.

An in-ground drainage area.

A wet section of the garden where drainage planning is needed.

A landscaping job where a lightweight drainage aggregate is required.

It is also worth asking the HGS team if you are comparing scoria with screenings or crushed rock. Many products can look similar if you are not working with them every day, but they can behave very differently once installed.

Using the wrong material can lead to extra work, extra cost and a fair bit of frustration. It is much easier to ask first, load once and get the job moving.

Planning Your Scoria Order

Before ordering Scoria 20mm, take a few measurements of the area you need to fill. The quantity you need will depend on the length, width and depth of the drainage zone.

For a retaining wall, measure the length of the wall and consider the drainage space behind it. For an in-ground drainage job, measure the area and depth as accurately as possible.

It also helps to think about access. Can the delivery truck tip close to where you are working? Will you be moving the material by wheelbarrow, machine, ute or trailer? Is there room for the load to be placed safely?

HGS has its own delivery fleet and supplies both residential and trade customers. If you prefer to collect, you can visit the Hurstbridge or Gembrook yard and the team can help load your ute or trailer.

What Else Might You Need?

Scoria is often only one part of a landscaping or drainage project. Depending on the job, you may also need other products from the HGS range, such as screenings, crushed rock, sands, soils, sleepers, cement products or building and plumbing products.

The best product mix depends on what you are building. A retaining wall project may call for different materials compared with a path, driveway, garden bed or drainage trench.

That is where local advice helps. The team at HGS can help you understand what is available and point you toward the right product range for your project.

Get Scoria 20mm from HGS Garden Supplies

Scoria 20mm is a practical choice when you need a lightweight aggregate for in-ground drainage or behind retaining walls. It is not flashy, but it does an important job where water movement matters.

HGS supplies Scoria 20mm from its Screenings & Crushed Rock range, with support for both homeowners and trade customers. Visit the team at Hurstbridge or Gembrook, or get in touch with HGS to organise your next order.

Need help choosing between scoria, crushed rock or screenings? Talk to the HGS team before you start the job. A little advice at the start can save a lot of digging later.