Why pea gravel falls short under artificial grass
Pea gravel is rounded and smooth, so it does not interlock. That means movement, settlement, and a bumpy surface that shows through the turf.
- Low interlock: rounded stones roll under load, creating depressions, ripples, and seam stress.
- Poor compaction: density and bearing strength stay low because particles slide past each other.
- Edge migration: stones creep at borders and under brushing, which loosens nails and staples.
- Moisture and freeze cycles: movement worsens with wet-dry and freeze-thaw, leading to unevenness.
- Comfort and access: wheels, chair legs, and pet traffic sink and rattle on loose rock.
The right base instead: angular crushed stone
Use an angular, graded base that locks tight under compaction and still drains fast. Crushed limestone or granite road base with fines is the standard, finished with a thin layer of finer angular material for smooth grading.
Recommended gradations
- Primary base: 3/4 inch minus angular crushed stone (with fines) for structure and interlock.
- Finish layer: 1/4 inch minus crushed stone or decomposed granite for final screed.
- Wet sites option: a thin, clean, open-graded angular chip layer beneath the base, fully separated by geotextile.
Depth and compaction targets
- Typical lawns and play areas: 3 to 4 inches compacted base.
- High traffic, equipment pads, or vehicle-adjacent edges: 5 to 6 inches compacted base.
- Place base in lifts no thicker than 2 inches and compact each lift.
- Compaction: target 95% of modified Proctor or equivalent field density with a plate compactor. Dampen material for best results.
Drainage and slope
- Maintain 1 to 2 percent surface slope away from structures.
- Avoid low spots. Shape and screed for consistent plane and positive drainage.
- Use permeable, washed materials for any clean drainage layers; keep fines out of those layers.
Soils and climate adjustments
- Expansive clays or freeze-thaw regions: increase base depth and install a separation geotextile over the subgrade.
- Poor subgrade: remove organic material, proof-roll to identify soft spots, and remediate before placing base.
- Sandy soils: add robust edge restraint to prevent raveling.
Containment and separation
- Edge restraint: concrete curbing, composite bender board, or steel edging to hold the base profile.
- Geotextile: non-woven separation fabric between subgrade and base to prevent fines pumping and to enhance stability.
- Fastening: secure turf with nails or staples into the compacted base per manufacturer guidance.
Step-by-step base build checklist
- Call to locate utilities, then mark work limits and desired finished elevations.
- Excavate and remove sod, roots, and organics to the required depth plus turf thickness.
- Shape subgrade to 1 to 2 percent slope; proof-roll and correct any soft spots.
- Place separation geotextile over the prepared subgrade.
- Install 3/4 inch minus base in 2 inch lifts, wetting and compacting each lift.
- Screed a 1/4 inch minus finish layer to tight tolerance for smoothness.
- Final compaction and surface check; correct any dips or highs.
- Install turf, seam, secure edges, and brush infill per spec.
Can I use pea gravel anywhere in a turf system?
Use pea gravel only where it is fully contained and not acting as the primary base. Examples include a thin, clean drainage layer beneath a geotextile and capped by angular base, decorative borders outside the turf area, or in separate French drains. Do not use pea gravel as the leveling or structural layer under the turf.
Quick specs at a glance
- Base type: angular crushed stone with fines, interlocking.
- Base depth: 3 to 4 inches typical; 5 to 6 inches for heavy use or weak soils.
- Finish layer: 1/4 inch minus or decomposed granite for final grade.
- Compaction: lift thickness 2 inches max; target 95% density.
- Slope: 1 to 2 percent away from structures.
- Separation: non-woven geotextile between subgrade and base.
- Edge restraint: rigid and continuous around the perimeter.
