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Grass Court Glossary: Terms for Building, Maintaining and Playing

This glossary defines the terms used in building, maintaining and playing on grass tennis courts, from aeration to the two-bounce rule. Definitions are short; where a full guide exists, the term links to it. Figures given are examples from named sources, not universal standards.

A to C

Aeration: Any operation that makes holes or slits in the soil to let air and water in and relieve compaction. Methods include slit tining, solid tining and hollow tining. See aerating your grass court.
Ball rebound: The height a dropped ball bounces from the court, often expressed as a percentage of its rebound from concrete. The AELTC measures it daily during The Championships.
Baseline wear: Loss of grass behind and along the baseline, where players spend most time. It is the main repair job at end-of-season renovation; see repairing worn grass courts.
Bent grass: Grasses of the genus Agrostis. Browntop bent (Agrostis capillaris) is a fine-leaved species that tolerates very close mowing, traditionally mixed with fescues for fine turf.
Bermudagrass: The North American name for Cynodon dactylon, known in Australia as couch grass.
Brushing: Sweeping the surface before mowing to lift the grass and remove dew and debris, so the mower cuts cleanly.
Clay content: The proportion of clay particles (smaller than 2 micrometres) in the soil. Clay gives a court its firmness when rolled; the AELTC courts have 18 per cent clay.
Clegg hammer: A drop-weight device for measuring surface hardness. The standard Clegg Impact Soil Tester drops a 2.25 kg (5 lb) mass from 455 mm (about 18 in) and records peak deceleration. See the Clegg impact soil tester.
Consolidation: Firming the soil profile by rolling, usually in spring before the season. Rolling works best when the soil is moist enough to be plastic but not wet.
Couch grass: In Australia, the warm-season species Cynodon dactylon, used on grass courts in warm climates. In the UK the same name refers to a different plant, a weed grass. See rye and bermuda grass.
Cultivar: A named variety selected within a species for traits such as wear tolerance, fine leaf, density and tolerance of close mowing. Variety choice can matter as much as species choice.
Cylinder mower: A mower with a rotating reel of blades cutting against a fixed bottom blade, giving the clean, close cut needed on courts. See mowing grass tennis courts.

D to G

Dethatching: Mechanical removal of thatch with vertically rotating blades or tines. Scarifying is the usual UK term.
Fescue: Grasses of the genus Festuca. Red fescues (Festuca rubra) are fine-leaved and tolerate close mowing and drought but are not very wear tolerant. The AELTC used a 70:30 ryegrass to creeping red fescue mix until 2001.
Fibre-reinforced rootzone: A rootzone with short synthetic fibres mixed through it to add stability. A form of hybrid grass.
Foxing: The rubber strip around the toe and edge of a shoe. AELTC rules require the foxing around the toes of grass court shoes to be smooth.
Fraise mowing: Removal of the surface layer of turf, thatch and some soil with a horizontally rotating cutter. It must not be used on stitched hybrid grass because it strips the fibres.
Germination: The sprouting of seed into a seedling. It needs moisture, warmth and good seed to soil contact, which is why renovation is timed while soil is still warm.
Gmax: A measure of surface hardness: the peak deceleration of a dropped mass on impact, as a multiple of gravity. Higher Gmax means a harder surface. The AELTC targets 170 to 220 gravities on day one of The Championships.
Groundsman: The person responsible for preparing and maintaining the courts; at small clubs often a volunteer. See a day in the life of a lawn tennis groundsman.

H to L

Hollow tining: Aeration with hollow tines that remove cores of soil, relieving compaction and removing organic matter. The holes are often filled with top dressing.
Hybrid grass: Natural turf reinforced with synthetic fibres that are stitched in, mixed through the rootzone or held in a backing mat. See natural versus artificial grass courts.
Live grass cover: The proportion of the surface covered by living grass, usually measured on high-wear areas. The AELTC measures it with a point quadrat.
Loam: A soil made of a balanced mixture of sand, silt and clay. Grass courts use loams with enough clay to bind and firm when rolled; see the best soil for grass courts.

M to O

Mowing height: The height of cut. The AELTC cuts its courts at 8 mm (5/16 in) during The Championships; club guidance commonly gives 8 to 10 mm for the playing season.
One-third rule: Remove no more than one third of the leaf height at any single cut, to avoid stressing the grass.
Overseeding: Sowing seed into an existing sward to thicken it or replace worn grass, usually during renovation. The AELTC uses about 10 tonnes of seed a year.

P to R

Particle size distribution: A laboratory test giving the proportions of sand, silt and clay in a soil. It is used to choose loam and top dressing.
Perennial ryegrass: Lolium perenne, the most widely used sports turf species in the UK. It establishes quickly and tolerates wear; AELTC courts have been sown with 100 per cent perennial ryegrass since 2001. See types of grass used for tennis courts.
Pimpled sole: A rubber shoe sole covered with small raised studs, the standard pattern for grass court shoes because it grips without tearing turf.
Poa annua: Annual meadow-grass, a weed grass that invades fine turf. The AELTC uses steam treatment partly to control it.
Point quadrat: A frame with pins lowered on to the turf; the number of pins touching live grass gives the live grass cover.
Renovation: The end-of-season programme of scarifying, aeration, levelling, top dressing and overseeding. The AELTC renovates in August and September; in Australia renovation falls in autumn.
Rolling: Pressing the surface with a heavy roller to consolidate the soil and produce a firm, true bounce. Rolling is usually done across the line of play first, then down it.
Rootzone: The soil layer in which grass roots grow. At the AELTC it is 275 mm deep and roots reach about 200 mm by The Championships; see grass layer thickness.

S

Scarifying: Cutting into the surface with vertical blades to remove thatch and lateral growth. Pitchcare defines it as working deeper than about 9.5 mm, unlike verticutting.
Serve and volley: A playing style in which the server moves straight to the net to volley the return. Low, fast grass bounces have long favoured it.
Slice: A shot struck with backspin, which skids and stays low on grass. See master the slice on grass.
Slit tining: Aeration with flat, knife-like tines that cut slits with little surface disturbance. Pedestrian machines work from about 75 to 150 mm (3 to 6 in) deep.
Steam sterilisation: Treating soil with high-temperature steam to kill weed seeds, pests and fungi. The AELTC has used it since 2017.
Stitched hybrid: A hybrid surface in which synthetic fibres are stitched vertically into the soil on a grid by a specialist machine.
Sward: The layer of grass plants forming the playing surface.

T to Z

Thatch: A layer of living and dead stems, leaves and roots between the green leaves and the soil. A thin layer adds resilience; a thick one holds water, softens the surface and deadens the bounce.
Top dressing: A thin layer of soil or loam spread over the turf and worked in to fill hollows, true the levels and dilute thatch. It should match the existing soil. See top-dressing your grass court.
Transfer wheel marker: A line marker in which a wheel picks up marking compound and transfers it to the grass.
Two-bounce rule: In wheelchair tennis the player may let the ball bounce twice and must return it before a third bounce. The second bounce may land in or out of the court.
Verticutting: Cutting the grass with vertical blades set just above the soil, to trim lateral growth and thin the sward. The GMA notes that, unlike scarifying, the blade does not enter the soil.
Volumetric soil moisture: The proportion of soil volume taken up by water, measured with probes; it guides watering and rolling.
White line marking: Court lines applied with a white compound, not paint. The AELTC uses a titanium dioxide compound; its lines are 50 mm wide and baselines 100 mm. See how to mark lines on grass courts.
Whites: Predominantly white clothing; the AELTC requires competitors’ clothing to be almost entirely white.