Simply put, it is not advisable to lay new turf on top of existing grass. While it is technically possible to place new turf rolls directly onto an old lawn, this method is strongly discouraged due to the significant problems it creates.
Why You Shouldn't Lay New Turf on Old Grass
Based on expert advice, attempting to turf over turf leads to a number of negative consequences that severely impact the health and appearance of your new lawn.
- Poor Rooting: The roots of the new turf will struggle to penetrate the dense layer of existing grass and thatch underneath. This prevents them from properly establishing in the soil, leading to weak growth and vulnerability.
- Competition for Resources: The old grass underneath will compete with the new turf for water, nutrients, and light. This unequal competition will weaken the new turf.
- Drainage Issues: The layer of old grass can impede proper water drainage, potentially leading to waterlogged conditions which are detrimental to turf health and can encourage fungal diseases.
- Soil Condition Decline: As the reference states, laying turf on top of existing grass "will cause a number of issues to develop, and result in a serious decline in overall soil condition." The trapped old grass may rot unevenly, creating anaerobic conditions and poor soil structure over time.
- Uneven Surface: The bumps and dips in the old lawn will likely transfer through the new turf, resulting in an uneven and unprofessional finish.
The Recommended Method: Start Fresh
For a healthy, long-lasting, and beautiful lawn, the correct approach involves preparing the area properly before laying new turf.
Here’s a simplified overview of the recommended steps:
- Remove Existing Lawn: Use a turf cutter or shovel to remove the old grass and a few inches of soil.
- Prepare the Soil: Dig or rotavate the area to break up compacted soil. Remove any stones, weeds, or debris.
- Improve Soil Quality: Incorporate fresh topsoil or soil improvers (like compost or well-rotted manure) if needed. This provides essential nutrients and improves drainage.
- Level and Consolidate: Rake the surface smooth and level, removing any lumps or bumps. Lightly compact the soil by walking over it with your heels or using a roller.
- Lay the New Turf: Install the new turf rolls tightly together on the prepared surface.
- Water Thoroughly: Water the new turf immediately and continue to water regularly as it establishes.
Taking the time to prepare the ground correctly ensures that the new turf's roots can grow deep into the soil, establishing a strong, healthy, and resilient lawn.
In summary, while you can technically place new turf on old, it is not advisable and will lead to numerous problems and a "serious decline in overall soil condition," according to the reference. For the best results, always remove the old lawn first.
