Homeowners and landscape designers often wonder if grass can take root in the gaps between paving stones. The short answer is yes, but success depends on understanding the specific conditions created by paver sand. While sand provides a loose, unstable medium that is not naturally conducive to robust root development, grass seeds can germinate and establish thin patches if the environment is managed correctly.
The Role of Paver Sand in Joint Stability
Paver sand, specifically coarse masonry sand, is engineered to lock together interlocking concrete or stone units. Its angular, irregular shape allows the granules to bind tightly, creating a stable base that prevents shifting and sinking. This compacted layer is designed to be a structural element, not a growth medium. Because it lacks organic matter and moisture-retentive properties, it forms a difficult substrate for seeds to anchor and thrive.
Challenges for Grass Establishment
- Lack of Nutrients: The sand is inert, offering no nutritional value to support the growth of blades or roots.
- Rapid Drainage: Water passes through the joints almost instantly, preventing the consistent moisture required for germination and early development.
- Foot Traffic: The frequent movement over joints compresses the sand, making it even harder for fragile seedlings to establish themselves.
Conditions That Encourage Growth
Despite the challenges, grass will attempt to grow through paver sand if specific criteria are met. The seeds must be fine fescues or bentgrass varieties that require minimal soil depth. Additionally, the sand must stay consistently moist—not saturated, but damp—which is often difficult to achieve in open joints. High levels of organic sediment blowing into the cracks can also help create a thin layer of viable topsoil over time.
Maintenance Strategies for Success
To encourage growth, regular intervention is necessary. Lightly raking the sand to expose the seeds to air, followed by gentle watering two to three times per day, can keep the environment favorable. Applying a starter fertilizer mixed with sand can provide the necessary nutrients, though this risks washing away during heavy rain. The most effective method is to overseed the surrounding soil and allow the new grass to spread naturally into the joints.
Weed Competition vs. Desired Grass
It is important to distinguish between grass and weeds in these gaps. Most often, what emerges in paver sand are opportunistic weeds like crabgrass or moss, which are far hardier than cultivated grass. These weeds compete for space and moisture, often choking out any desired lawn species. If the goal is a seamless lawn, allowing weeds to dominate the joints will hinder the process of grass taking over.
Long-Term Solutions and Alternatives
For a permanent solution, consider whether grass is the right choice for the joint. Sand joints are ideal for low-growing ground covers like thyme or clover, which can handle dry conditions and foot traffic better than traditional lawn grass. If a soft, green lawn is the objective, polymeric sand—which hardens when wet—may be a better choice. This prevents weed growth in the gaps while allowing grass seeds sown directly into the surrounding soil to eventually cover the surface uniformly.
