The short answer is you generally shouldn't install artificial grass directly on top of existing grass. Proper installation involves removing the existing grass and preparing a suitable sub-base for drainage and stability.
Here's why and what you should do instead:
Why You Shouldn't Install Artificial Grass Directly on Grass
- Poor Drainage: Grass and the soil underneath retain water. Covering it with artificial grass will trap moisture, leading to mold, mildew, and unpleasant odors.
- Uneven Surface: Existing grass creates an uneven base, resulting in an unnatural and bumpy appearance for your artificial lawn.
- Weed Growth: Weeds can still grow through the artificial grass if the underlying grass and soil are not properly removed and a weed barrier installed.
- Instability: The lack of a compacted sub-base will cause the artificial grass to shift and sink over time, leading to an unstable surface.
The Correct Method: Preparing the Base for Artificial Grass
Here's a step-by-step guide for proper installation:
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Remove Existing Grass: Use a sod cutter or shovel to remove all existing grass and at least 2-4 inches of topsoil. This ensures a clean and level base.
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Install a Weed Barrier: Lay down a high-quality weed barrier fabric over the exposed soil. This prevents weeds from growing up through the artificial grass.
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Install Edging (Optional): Install edging around the perimeter of the area to contain the base materials and provide a clean, finished look. Materials like treated lumber, plastic edging, or metal edging can be used.
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Add a Sub-Base: A compacted sub-base is crucial for proper drainage and stability. Use a layer of crushed aggregate (like crushed stone or decomposed granite) typically 2-4 inches thick.
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Compact the Sub-Base: Use a plate compactor to thoroughly compact the sub-base. This creates a solid and level surface. Compaction is vital.
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Add a Levelling Layer (Optional): A thin layer of fine aggregate or sand can be spread over the compacted sub-base to create an even smoother surface.
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Roll Out the Artificial Grass: Unroll the artificial grass over the prepared base. Allow it to sit in the sun for a few hours to acclimate and relax.
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Trim and Join: Trim the artificial grass to fit the area, leaving a small amount of excess. If you have multiple pieces, use seaming tape and adhesive to join them together.
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Secure the Edges: Secure the edges of the artificial grass to the perimeter using landscape staples or nails. Space them evenly to keep the grass taut.
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Add Infill (Optional): Infill materials like silica sand or crumb rubber can be spread over the artificial grass to help the blades stand upright and provide cushioning.
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Brush and Groom: Use a stiff brush or power broom to brush the infill into the grass fibers and fluff up the blades.
Quick-Fix Temporary Solutions (Not Recommended Long-Term)
While not recommended, in situations where you absolutely must install artificial grass over existing grass temporarily (e.g., for a short-term event), consider these points:
- Mowing: Cut the existing grass as short as possible before laying down the artificial grass.
- Drainage: Consider using a perforated underlayment to allow for some drainage.
- Expect Imperfections: Be aware that the surface will likely be uneven and prone to issues like mold and weeds.
- Limited Lifespan: This is a temporary solution only.
Conclusion
Proper installation of artificial grass requires removing the existing grass and creating a well-draining and stable sub-base. Attempting to install it directly on grass will lead to problems and a less-than-desirable result. Follow the recommended steps for a long-lasting and beautiful artificial lawn.
