What to Put Under Artificial Grass | The Ultimate Guide to Artificial Grass Base

When planning to install artificial grass, most people focus on the turf itself — its color, pile height, or softness. While the turf gives your lawn its look and feel, a properly prepared artificial grass base is essential for long-lasting performance.

A solid, well-constructed base provides the foundation for a smooth and stable lawn. It ensures effective drainage, prevents weed growth, avoids sinking, shifting or uneven spots, and helps your turf maintain a flawless appearance year after year.

So, what do you put under artificial grass? Let’s break it down layer by layer.

Overview: The 4 key layers uFnder artificial grass

Before diving into materials and methods, here’s a quick look at the structure beneath a typical artificial lawn:

Layer	Main Purpose	Common Materials
1. Weed Barrier	Weed prevention	Geotextile fabric, mesh weed membrane
2. Sub-base	Stability & Drainage	Crushed stone, decomposed granite, gravel (as a drainage layer)
3. Levelling Layer	Smooth surface	Sharp sand, granite dust
4. Cushion/Optional Layer	Safety & comfort	Foam pad, drainage tiles

Each layer has a specific role in creating a long-lasting installation. The following sections explain how to choose and install each one properly.

Weed membrane: Stop unwanted growth

A weed membrane is recommended when installing artificial grass over natural soil, especially in areas prone to weed growth. It blocks unwanted vegetation and keeps the sub-base separate from the soil, maintaining stability and proper drainage.

Types of weed membrane

• Woven geotextile fabric: Durable and ideal for high-use or heavy-traffic areas.
• Non-woven fabric: Lightweight, cost-effective, and easy to handle for residential installations.

Installation tips

• Lay the fabric evenly over the excavated area and compact the soil beneath to create a firm, level surface.
• Overlap each section by 2–3 inches to ensure full coverage and prevent weeds from finding gaps.
• Fix the fabric securely using landscape pins or galvanized nails, keeping it flat and tight across the area.

Note: For pet-friendly artificial lawns, some installers prefer to skip the membrane to improve drainage and odor control. In such cases, a well-compacted sub-base combined with an eco-friendly pre-mixed weed preventer can offer effective long-term protection against weed growth.

Artificial grass base: Build a strong and smooth foundation

The sub-base and leveling layer provide the main support for your turf, ensuring proper drainage and a smooth, even surface. Choosing the right materials is essential—so, what is the best base for artificial turf?

Sub-base: Stability & drainage

The sub-base is the primary load-bearing layer of your artificial grass installation. Its critical role is to create a stable foundation that resists shifting or settling, while ensuring efficient water drainage away from the surface.

Recommended materials for the sub-base

1. Crushedstone (¾-inch minus/ Type 2) – The premium choice

A graded mix of angular, mechanically fractured stones (up to ¾ inch) blended with fine dust. This is the industry standard and the most reliable material for a high-performance sub-base.

Key advantages:

• Superior stability: The jagged particles interlock tightly when compacted, forming a rigid, interlocking structure that resists movement and settling even under heavy loads.
• Excellent drainage: The gaps between the locked stones allow water to flow freely, preventing pooling.
• Ideal for: Most installations, especially high-traffic areas, regions with frequent rainfall, and projects requiring long-term durability.

2. Decomposed granite (DG)

DG is a sandy, granular material produced by the natural weathering of granite. It can perform well in the right conditions but requires careful consideration of the site environment.

Key advantage: Forms a hard, slab-like base when compacted dry, providing a smooth, even support for turf.

Important considerations: Because of its higher fines content, DG drains more slowly than crushed stone and can soften slightly when saturated. It’s best suited for well-drained soils and arid climates.

3. Gravel (pea gravel)– Limited & specialized use

Gravel consists of smooth, rounded stones formed by natural erosion. It’s generally unsuitable as a primary sub-base due to its lack of structural cohesion.

Key limitation: Poor stability — the round particles don’t interlock well, leading to shifting and uneven surfaces over time.

Appropriate application: Best used as a secondary drainage layer beneath a crushed stone base in areas with extremely poor soil drainage.

Installation tips

• Compact the sub-base in 2-inch layers (lifts) for maximum density.
• Keep the material slightly damp during compaction to help bind particles.
• Ensure the final surface has a gentle slope (1–2%) away from buildings for proper runoff.

Leveling layer: The perfect finish

Once the sub-base is fully compacted, the leveling layer is applied. This final course creates a perfectly smooth surface, allowing the turf to lie flat, feel comfortable underfoot, and facilitate surface drainage.

Recommended materials for the leveling layer

1. Sharp sand or concrete sand

A coarse, washed sand with angular grains — one of the most popular materials for creating a smooth and stable finish.

Key advantages:

• Workability: Easy to spread and screed for precise leveling.
• Drainage: The angular structure remains porous, allowing water to pass through efficiently.

2. Granite dust (stone dust)

A byproduct of stone crushing, consisting of fine particles and dust. It produces an exceptionally smooth and firm surface.

Key advantage: Excellent for filling minor imperfections and ensuring a dense, ultra-smooth surface.

Important consideration: Less permeable than sand, so it should only be used in thin layers (up to 1 inch) over a well-draining sub-base.

Tips for a perfect finish

• Avoid using fine sand, soil, or dirt — they trap moisture and can lead to uneven sinking.
• Use a screed board over guide rails to achieve a flat, even finish.
• Do not over-compact; a light tamping is sufficient to settle the material.

Optional cushion & drainage layers

Cushion and drainage layers are not required for every installation, but they can be useful depending on the project type.

Shock pad / foam underlay

• Adds extra softness and impact absorption, ideal for playgrounds, gyms, or pet zones.
• Reduces stress on joints and provides a natural feel underfoot.
• Useful when installing over hard surfaces like concrete to smooth minor imperfections.

Drainage tiles

• Designed for installations on rooftops, balconies, or concrete surfaces.
• Improve water runoff and allow airflow beneath the turf.
• Easy to install — simply snap together the modular panels.

If the existing surface already drains well, a drainage layer is not necessary.

Conclusion

The secret to a beautiful and long-lasting artificial lawn lies in what’s underneath it.

By understanding what to put under artificial grass — including the weed barrier, sub-base, leveling layer, and optional cushion or drainage layers — you’ll create a strong foundation for lasting performance.

Whether it’s a home garden, playground, or pet area, taking the time to build a reliable base will ensure your artificial grass stays smooth, stable, and easy to maintain for years to come.