Gouache painting of groundstaff mowing and rolling grass courts at dawn

For groundstaff

Grass court maintenance calendar

This calendar is for groundstaff, volunteers and committee members who look after natural grass tennis courts. It sets out, month by month, the main jobs for three broad climates: temperate courts sown with ryegrass, hot-climate courts on couch (Bermuda) grass, and tropical courts that follow a wet and dry season. Each month gives a phase, a mowing height and frequency, the key tasks and the main risk to watch for.

Treat the months as a guide to sequence, not fixed dates. Grass growth follows soil temperature and moisture, so a cold spring, a wet autumn or a late monsoon moves every job, and your own playing season and tournament dates should set the timetable. Southern hemisphere clubs in temperate and hot climates should read each month six months on; tropical clubs should line the calendar up with their local wet season. Keep records of what you did and when, and adjust next year's dates from them.

Free for members

Print it for the groundstaff hut

Each climate on its own sheet of A3: twelve months of mowing heights, jobs and risks to watch, with the southern hemisphere months alongside.

See the A3 calendars, free for members Already a member? Log in
Your climate
Hemisphere

Where: UK, Ireland, northern Europe, New Zealand, southern Australia's cooler regions, the US north-east

Grasses: perennial ryegrass, with fescues and bents (as used at Wimbledon: 100% perennial ryegrass since 2001)

Courts play from late spring to late summer, are renovated straight after the last matches, and rest through winter. The main variable is height of cut: about 12 to 18 mm in winter (Wimbledon holds 13 mm), lowered about 1 mm at a time through spring to a playing height of about 8 mm (6 to 10 mm at club level), then cut right down for renovation. Months are written for the northern hemisphere; in the southern hemisphere add six months.

  1. January Winter rest

    Mowing: Winter height of about 12 to 18 mm (Wimbledon holds 13 mm); mow only when the surface is dry and firm enough to carry the mower.

    • Finish any deep solid or slit tine aeration this month on clay loam courts.
    • Send cylinder mowers for servicing and regrinding before dealers get busy.
    • Order seed, fertiliser, loam top dressing and line marking material for the year.
    • Book a soil analysis to guide the spring feeding programme.
    • Clear leaves and debris, and keep traffic off frozen or waterlogged turf.

    Watch for: Microdochium patch (fusarium) in mild, wet spells; leaf litter and long periods of surface wetness make it worse.

  2. February Late winter

    Mowing: Winter height of about 12 to 18 mm; top with a rotary mower when dry to tidy the sward and clear debris.

    • Avoid deep aeration from now on: holes in clay soils can open and crack as the courts dry in spring.
    • Use a sarrel roller to keep the top 25 to 30 mm open if water sits on the surface.
    • Brush off morning dew to reduce leaf wetness.
    • Check covers, nets, posts and line markers, and repair or replace before spring.
    • Settle any frost heave with a very light roll only if the surface is dry enough.

    Watch for: Waterlogging and moss on poorly drained courts; moss signals weak grass and poor drainage, not a cause in itself.

  3. March Early spring

    Mowing: At least 2 cuts a week as growth starts; begin lowering from the winter height about 1 mm a week, mowing in different directions.

    • Start consolidation rolling when soil moisture allows, with a light roller or unballasted mower, rolling across the line of play first.
    • Apply a spring feed once the soil has warmed (about 11°C) and growth is under way, guided by the soil analysis.
    • Sarrel roll before feeding to help granules and liquids into the surface.
    • Oversow thin or bare areas when weather allows; germination sheets improve success.
    • Brush daily to remove dew and stand the grass up before mowing.

    Watch for: Rolling too heavy or too early, or on wet soil, which smears and compacts the clay rather than consolidating it.

  4. April Pre-season preparation

    Mowing: 2 to 3 cuts a week, continuing to lower towards a playing height of 8 to 10 mm; never remove more than a third of the leaf at one cut.

    • Roll across and then along the line of play, only when the soil is neither wet nor dry.
    • Verticut or lightly scarify every two weeks to remove lateral growth before the season.
    • Apply only a very light top dressing on a dry surface, with seed into thin areas.
    • Test the irrigation system and apply a wetting agent early if you use one.
    • Check for weeds, worm casts and pest activity.

    Watch for: Early dry spells that let the profile dry out before the rolling programme has done its work.

  5. May Season opening

    Mowing: Reach playing height: about 8 mm at Wimbledon, 6 to 10 mm at club level depending on the standard of play; 3 cuts a week.

    • Complete the first marking out with string lines and a clean, serviced marker.
    • Erect nets and posts and set up court furniture.
    • Keep rolling to build firmness; check hardness and bounce if you have the equipment.
    • Open courts only once firmness and evenness are acceptable.
    • Treat broadleaf weeds by hand or with a selective herbicide while grass is growing strongly.

    Watch for: Red thread in cool, wet weather on slow-growing turf; it often shows the sward needs a feed.

  6. June Playing season

    Mowing: About 7 to 8 mm, at least 3 cuts a week; some clubs cut daily. Brush before mowing and keep cylinders sharp.

    • Roll with a 1 to 1.5 tonne roller when conditions allow, aiming for 6 to 10 hours a week before matches.
    • Water in dry spells so moisture reaches at least 150 mm into the rootzone, checked with a probe; time it so courts are dry for play.
    • Apply wetting agents monthly through summer to prevent dry patch.
    • Feed sparingly, ideally with liquid products; avoid heavy nitrogen, which gives lush, weak growth.
    • Remark lines as play requires, and repair worn baselines with seed and top dressing.
    • Spike only the top of the surface with a sarrel roller; keep deep tines off.

    Watch for: Dry patch and drought stress as the clay loam dries; uneven water penetration leaves patches of poor turf.

  7. July Peak season

    Mowing: Hold 6 to 10 mm depending on the level of play (8 mm at Wimbledon), at least 3 cuts a week or daily for events.

    • Brush daily before mowing to remove dew and improve the cut.
    • Continue the irrigation, wetting agent and rolling programmes.
    • Rotate courts in play to spread wear, and repair baselines as they thin.
    • Feed according to the annual programme, guided by the soil analysis.
    • Keep wet weather covers ready and in good repair.

    Watch for: Cracking of clay soils in hot, dry weather, which deep aeration in the season makes worse.

  8. August Late season

    Mowing: Playing height until the last matches, then raise slightly to relieve stress.

    • Take core samples from each court to measure thatch and set scarifier depth.
    • Confirm all renovation materials and any hired machinery or contractors.
    • Check scarifier belts, drives and blades.
    • Start renovation as soon as play ends; Wimbledon begins renovating within days of its tournament ending.
    • Monitor for crane fly and chafer activity in areas with a history of damage.

    Watch for: Drought stress and cracking at the end of a dry summer, just as the courts need moisture for renovation.

  9. September End-of-season renovation

    Mowing: Mow down to about 3 to 4 mm to clean out the surface before scarifying; after seeding, leave until the new grass needs its first cut.

    • Scarify to 4 to 15 mm depending on thatch, usually in two directions, never at right angles to the previous pass; clear debris.
    • Hollow tine to 75 to 100 mm every couple of years or where thatch is severe; otherwise solid or slit tine (100 to 200 mm).
    • Top dress with a loam compatible with the existing soil, about 3 kg/m² as a guide, spread in dry weather and worked in with a lute or drag mat.
    • Overseed perennial ryegrass into the grooves or holes; it germinates in 7 to 14 days with warmth and moisture.
    • Apply a low-nitrogen autumn fertiliser (for example NPK 5:5:15).
    • Keep the seedbed moist until the new grass establishes; store the nets and posts.

    Watch for: A dry seedbed after sowing; seed that germinates and then dries out will fail.

  10. October Autumn establishment

    Mowing: Cut new growth at about 20 mm with clippings collected, then settle to the winter height; weekly cuts, removing no more than a third.

    • Finish late seeding while air temperatures still average 10 to 12°C.
    • Use slow-release nitrogen sources and avoid flushes of soft growth.
    • Raise cutting heights and avoid stressful work such as heavy top dressing.
    • Brush or switch dew off before mowing.
    • Disperse worm casts once dry, and clear leaves promptly.

    Watch for: Microdochium patch (fusarium) and red thread as heavy dews return; leatherjackets hatch about two weeks after crane fly egg laying.

  11. November Into winter

    Mowing: Winter height of about 12 to 18 mm, cut only when conditions allow.

    • Pencil or solid tine when the soil is suitable.
    • Apply an iron-based product to harden the sward and hold colour.
    • Fit off-season covers where used and lift them regularly to check for disease.
    • Keep traffic off frozen or waterlogged turf.
    • Clean all machinery, check air filters and book winter servicing.

    Watch for: Microdochium patch in mild, damp weather, especially under leaves or after late nitrogen.

  12. December Winter rest

    Mowing: Winter height of about 12 to 18 mm; mow only when dry and firm.

    • Continue aeration when ground conditions allow.
    • Clear leaves and debris from the courts and surrounds.
    • Review the year's records, measure wear and set the budget for next season.
    • Plan next year's dates for rolling, marking, renovation and tournaments.

    Watch for: Frost and waterlogging: walking or working on frozen or saturated turf damages both grass and soil.

Rules that apply all year

  • Never remove more than a third of the leaf in one cut, and change the height gradually: Wimbledon lowers its courts about 1 mm at a time from 13 mm in winter to 8 mm for play.
  • Typical playing heights: about 8 mm on ryegrass (6 to 10 mm at club level), and about 4 to 8 mm on couch. Keep cylinder blades sharp and check the height of cut daily in the season.
  • Roll only when the soil is neither wet nor dry. Start light and across the line of play, then build up; ball bounce depends mainly on a firm, dry soil, not the grass.
  • Water deeply and less often, so moisture reaches at least 150 mm, and water in the early morning; check with a probe rather than by eye.
  • Feed from a soil analysis. Avoid heavy nitrogen in the playing season and before cold or wet periods, when lush growth wears quickly and invites disease.
  • Only trained and properly certified operators should apply pesticides, following the product label and local law. Use a safe working method for heavy rollers, scarifiers and mowers, and keep people clear of machines.
  • Keep records: dates and rates of feeding, seeding and spraying, heights of cut, rainfall and irrigation, disease and pest sightings, and any hardness or bounce readings. They make next year's timing more accurate.
Sources

A guide to the order of work, not a substitute for advice on your own soil, grass and weather. Follow the label and local rules for any fertiliser or plant protection product.

Read our guide to the grass court year · All grass court guides · Find a supplier

Scroll to Top