How Wimbledon Grass Courts Are Prepared and Maintained

The mowers go out before six in the morning. Every one of the eighteen championship courts is cut, every day of the fortnight, to a height of eight millimetres, and the lines are re-marked behind the mower before the first spectators reach the turnstiles. It is the least glamorous quarter of an hour in professional sport and it is the reason a ball hit flat at the service line skids through at a predictable height on the second Saturday as well as the first Monday.

Grass is the only major tennis surface that is alive. Clay can be watered and rolled back into shape overnight; a hard court is a slab of acrylic over concrete or asphalt and behaves much the same in July as it did in April. A grass court is a crop being farmed to a deadline, and the deadline does not move. That single fact shapes everything the All England Club's grounds team does for the other fifty weeks of the year.

The ryegrass that carries the Championships

Since 2001 the championship courts have been sown with 100 per cent perennial ryegrass, Lolium perenne. Before that the club used a mix in which ryegrass was blended with creeping red fescue, a finer, softer-leaved grass that produced a beautiful sward and a lovely surface for the first three days, and then began to give way.

The change was made for durability rather than for speed, and the club has consistently said so, though it has never quite shaken the popular belief that the courts were deliberately slowed down. Two other things happened around the same period. Racket and string technology moved on considerably, and the balls used at the Championships were changed. Anyone attributing the shift in how grass-court tennis looks to the grass alone is picking one variable out of three. The honest position is that the surface became more consistent and more durable, that the game changed at the same time, and that unpicking the two after the fact is not really possible.

Why ryegrass and not something finer

Ryegrass has three properties that matter here. It germinates fast, which shortens the renovation window. It produces a tough, fibrous plant with a strong tiller base, so it can be walked on, slid across and served from without shearing off at the crown. And it knits into a dense mat that holds the soil surface together, which is what stops a court breaking up into divots when a player changes direction hard.

Cultivar choice inside the species matters as much as the species itself. Turf breeders produce dozens of perennial ryegrass cultivars and they differ measurably in wear tolerance, leaf fineness, disease resistance and how low they can be mown before they thin. The club trials cultivars and blends rather than buying seed off a shelf, and the mix used on the championship courts has been adjusted over the years as better material has become available. The principles behind that kind of selection are not secret — the same trial data underpins what a well-run club does, and the practical side is covered in our guide to maintaining grass tennis courts in England.

Why eight millimetres is the number

Eight millimetres is not an arbitrary tradition. It is the point at which two competing requirements meet.

Cut the grass shorter and the ball skids more cleanly, the bounce gets lower and truer, and the court plays quicker. Cut it shorter still and the plant loses too much leaf area to photosynthesise, the crown is exposed, and a court that has to survive fourteen days of professional tennis starts dying on day four. Leave the grass longer and it grips the ball, the bounce sits up, the footing becomes less certain, and the surface tears more readily when a player slides into a wide ball.

Eight millimetres gives a firm skid and a low bounce while leaving the plant something to live on. It is held there for the fortnight and for the run-up, and it is reached gradually. Taking a court from spring growth straight down to championship height in one pass would shock the sward badly. Instead the height is stepped down over weeks, a little at a time, so the plant adjusts to it.

The mowing is done with pedestrian cylinder mowers rather than ride-ons. A cylinder mower scissors the leaf against a bottom blade and leaves a clean cut; a rotary mower tears it, and a torn leaf tip browns off and looks it within a day. Direction is varied, too, so that the grass is not persuaded to lie one way — a court with a nap would play differently depending on which end a player was hitting from, which is exactly what all this work exists to prevent.

The renovation cycle, which starts almost immediately

The Championships finish on a Sunday. Renovation of the courts begins within days, and it is the single largest piece of work in the grounds calendar.

Stage	Roughly when	What happens
Strip and clean	Immediately after the fortnight	Remaining grass, thatch and debris taken off down to the soil surface
Cultivate and level	Late summer	Surface scarified, irregularities removed, levels re-established
Top-dress and seed	Late summer into September	Loam dressing applied and worked in, then seed sown at a heavy rate
Germination and grow-in	Autumn	Sward establishes, first cuts taken high, rooting encouraged
Winter rest	Winter	Courts closed, height of cut raised, disease and moss managed
Consolidation	Spring	Progressive rolling, feeding, gradual reduction in height of cut
Pre-Championships	Early summer	Final height reached, hardness and bounce measured and adjusted

The courts are effectively rebuilt at the surface every year. That is unusual. Most sports turf is repaired rather than reconstructed annually, and an annual rebuild is affordable at Wimbledon only because the courts are used for a fortnight rather than a season.

Getting a new sward through its first winter

The seed goes into a warm soil in late summer, which is the whole reason renovation cannot wait. Perennial ryegrass will germinate readily while soil temperatures stay up; sow the same seed six weeks later into a cooling autumn soil and germination is slow, patchy and vulnerable. A court sown at the right moment is green within a fortnight and has a root system worth the name before the first frost.

Germination sheets are used where establishment needs help. They are permeable covers laid over a seeded surface to hold warmth and moisture at the soil surface, and they buy a week or more of growing conditions at the end of the season. They also have to come off at the right time, because a sward kept warm and damp under a sheet for too long is an invitation to fungal disease.

Disease management through autumn and winter is largely preventative and largely cultural: keeping the surface dry, removing dew in the mornings, avoiding excessive soft growth from over-feeding, and maintaining air movement across the courts. Fungicide use in turf across the country has become much more constrained as active ingredients have been withdrawn from approval, and the practical consequence for every grass venue in England, Wimbledon included, is that avoiding disease matters more than curing it.

Levels matter more than anyone expects

A tennis court has to be flat to a tolerance that would embarrass most sports pitches, because a ball travelling quickly and landing at a shallow angle will exaggerate any deviation in the surface. A two-millimetre hollow that nobody could see with the naked eye is enough to send one ball in fifty somewhere it should not go. Renovation is the only chance in the year to correct levels, and a good deal of that work is laser-guided grading rather than anything horticultural. Once the seed is down and the sward has knitted, the levels are locked in until the following summer.

Soil, rolling and where the bounce comes from

The grass gets the attention. The soil does the work.

Wimbledon's courts sit on a heavy loam with a high clay content, and that is the reason a Wimbledon bounce is what it is. Clay-rich loam consolidates under rolling into a dense, firm profile that does not absorb impact. The ball meets a hard surface with a thin living skin on top, skids, and stays low. A sandier root zone would drain faster and be considerably kinder to the grass plant, but it would give a softer, deader, higher bounce — which is precisely what many club courts on lighter soils produce, and why the difference between a championship court and a good club court is more about what lies underneath than what grows on top.

Consolidation is achieved by rolling, and rolling is done progressively. Roll a soft spring court with a heavy roller and you smear the surface and seal it. Instead the weight is built up across weeks, starting light and finishing heavy, so the profile compacts evenly through its depth rather than crusting at the top and staying spongy below.

The drainage trade-off nobody can escape

Here is the tension that defines grass-court construction. Firmness and drainage pull in opposite directions. A heavy clay loam gives a magnificent playing surface and drains slowly, because water moves through fine-textured soil at a crawl. A sand-dominated root zone drains beautifully and plays soft. Football and rugby pitches, which must be playable in February and can tolerate a bouncier, softer surface, have largely gone the sand route, with sand-slit or fibre-reinforced constructions that shed water in minutes.

Tennis on grass cannot make that trade. The surface has to be firm, so the soil has to be heavy, so the court will never drain quickly. Covers exist precisely because drainage cannot be relied on. When people ask why a grass court takes so long to dry compared with a modern football pitch a few miles away, the answer is not neglect or a lack of engineering; it is a deliberate choice, made in favour of how the ball behaves, and paid for with a slower recovery from rain.

Measuring hardness rather than guessing it

Surface hardness is not left to judgement. It is measured with a drop-hammer device — the Clegg impact hammer is the standard instrument in sports turf — which records the deceleration of a known mass dropped from a known height. That produces a number, and numbers can be compared between courts and between days.

Alongside hardness, soil moisture is measured, because the two are directly linked. A court that has taken water is softer, and a softer court plays slower and lower. Ball rebound is checked as well, by dropping a ball from a fixed height and measuring how high it returns, which is the test the international governing body specifies as part of classifying a surface for pace.

The point of the instrumentation is not perfection. It is consistency across eighteen courts. A player who wins on court fourteen on Tuesday and is moved to Centre Court on Friday should not have to relearn the bounce, and the only way to promise that is to measure rather than to trust an experienced eye. How those readings translate into what a player actually feels underfoot is covered in our explainer on how grass courts play differently.

What the grounds team does across the fortnight

The fortnight is the least creative part of the year and much the most relentless. The pattern repeats daily.

Before play: courts inspected, mown to eight millimetres, lines re-marked, nets checked for height at the centre and at the posts, hardness and moisture readings taken, surrounds swept. Line marking is done with a wheeled transfer marker using a white paint formulated to sit on the leaf without scorching it, and the lines are redone every morning because a day of play scuffs them.

During play: a team on standby for every court. Their job is covers, and the speed with which covers go on is the single most consequential thing anyone on the grounds staff does in public. A court that takes water is not merely wet, it is soft, and a soft court is far slower to bring back than a damp one.

After play: courts assessed, damage recorded, divots on the baselines and around the net trodden back, watering decided. Watering during a championship is a judgement rather than a routine. Too little and the sward dries, thins and browns; too much and the surface softens, the bounce dies and the footing goes greasy. That decision is taken court by court, on the readings and on what the forecast suggests is coming.

The practice courts nobody sees

The championship courts are only part of the estate. A separate bank of practice courts sits at Aorangi Park, on the north side of the grounds, and they take a beating that the match courts never see. Every player in three singles draws, plus doubles and junior entrants, needs court time daily, and the practice courts absorb all of it — hours of repeated serving from the same spot, hitting from the same corner, without the mercy of a match that ends when someone loses.

Those courts are prepared to the same specification as the match courts, because a player warming up on a surface that plays differently from the one they are about to compete on is being actively misled. Keeping them consistent while they take five or six times the traffic is arguably the harder half of the job, and it is entirely invisible to anyone watching on television.

The court rotation

Not every court is used every day. The draw shrinks fast — 128 players in each singles event on the first Monday, sixteen left by the second — and as it shrinks, the outside courts come out of use. Courts that hosted first-round matches on days one and two may play nothing after the middle weekend, which gives them the better part of a week of recovery before the junior and invitation events arrive. That rotation is a maintenance decision as much as a scheduling one, and it is one of the quiet constraints on how the order of play can be built.

Covers, rain and bringing a court back

Wimbledon has full covers for its outside courts, deployed by teams of court attendants who train for it. The covers are pulled across from the side, sealed at the edges and weighted, and on a well-drilled court the whole operation takes under a minute from the umpire's call.

What happens next is less visible. Water that lands on a cover has to go somewhere, and getting it off without letting it run onto the court is the trick. Once the rain stops the covers come off, the surface is assessed, and if the grass is merely damp rather than the soil wet, play can resume quite quickly. If water has got in, the court is slower to return. Blowers and absorbent rollers can lift standing water off the leaf, but nothing pulls moisture back out of a clay loam profile in an afternoon.

That is the honest reason a rain delay at Wimbledon can be twenty minutes or the rest of the day, and why the two are not always predictable from the weather alone. The procedural side — who decides, what the rules require, what happens to a ticket — is set out in our guide to Wimbledon rain delay rules.

Why the baselines go bare

By the second Wednesday the baselines on the busiest courts are brown, then thin, then largely soil. Spectators new to grass sometimes read this as neglect. It is the opposite. It is the surface doing precisely what it was built to do, for as long as it possibly can.

Consider where the load falls. A server stands in roughly the same spot, loads onto the back foot and lands hard past the baseline. A returner stands a metre or two behind the line and pushes off laterally, often with a sliding stop. Over a five-set match that is many thousands of hard, twisting footfalls concentrated into two strips of turf perhaps two metres deep. Perennial ryegrass is about as tough as fine turf grass gets, and it still cannot regrow inside a fortnight — grass recovers by producing new tillers, and that takes weeks in good conditions, not days.

The centre of the court, meanwhile, often looks nearly untouched at the end of the fortnight, because in singles very few points are played standing there. The wear pattern is a map of where tennis is actually played, drawn in real time by the players themselves.

There is a further wrinkle. Wear is not symmetrical between the two ends of a court, because the sun is not symmetrical either. One baseline typically dries faster and firms up sooner, and on courts with significant shade from stands or trees the difference can be visible from the stands by the middle weekend. Umpires and players deal with it the way they deal with wind: it is part of the court, it applies to both players over the course of a match, and nobody expects it to be engineered away.

What the wear does to the tennis

A bare baseline behaves differently from a grassed one. It is firmer, marginally faster off the skid, and the footing is less forgiving because there is no leaf to grip against. Players adjust, and some prefer it. A worn, hard, dry baseline in the second week is closer in feel to a hard court than the lush surface of day one, which is part of why players who move well on hard courts often look more comfortable at Wimbledon as the fortnight goes on rather than less.

Centre Court, the roof and a court that is barely used

Centre Court is protected in a way no other court in the world is. It hosts a fortnight of tennis and very little else. That scarcity of use is the largest single reason it survives the second week in better condition than the outside courts, and it is a management decision rather than an accident of the soil.

The retractable roof, in use since 2009, changed the horticulture as well as the scheduling. A closed roof creates an enclosed environment over living grass, and an enclosed environment over living grass becomes humid very quickly — humid enough to leave the court slippery and to invite fungal disease. The answer is an air management system that conditions the air under the roof, controlling humidity and keeping the surface dry rather than simply keeping the rain off. Anyone who has watched play resume under a closed roof and thought the ball behaved slightly differently is not imagining it. The air is drier and warmer than the outside air it replaced, and both of those affect how a ball comes through.

The roof creates a second, slower problem. Structures cast shade, and grass in shade grows thin and weak. Supplementary lighting rigs are used to give the sward the light that the stands and the roof structure take away. That is now routine practice at enclosed football and rugby stadiums, but it was a novelty when tennis first had to deal with it. The full story of the roof — how the decision to close it is taken, what it does to the schedule, and the curfew sitting behind it — is in our Centre Court roof explainer.

The people who do the work

The permanent grounds team at the All England Club is small by the standards of the job it does, and it is supplemented heavily for the Championships by seasonal staff and by the court attendants who handle covers. The permanent staff are horticulturists and turf specialists. The seasonal cohort do the volume work of mowing, marking, sweeping and covering.

A day during the fortnight starts before dawn and finishes after the last ball, which under the roof can mean eleven at night. Between those two points the work is unglamorous and continuous: cut, mark, measure, water, cover, uncover, repair, record. Everything is recorded, because those records are what allow the following year's decisions to be taken on evidence rather than on memory of a hot fortnight three summers ago.

The rest of the year is quieter and considerably more technical. Autumn is establishment and disease management. Winter is protection, drainage and machinery overhaul. Spring is consolidation and the long, careful reduction in height of cut. By the time the Championships arrive, almost every horticultural decision that determines how the courts will play has already been taken, months earlier, by people whose names nobody watching will ever know.

Championship grass and club grass are not the same thing

This is worth stating plainly, because the comparison is the source of a great deal of misplaced ambition at club level. A Wimbledon court and a club grass court share a species and very little else.

	Championship court	Typical club grass court
Days of play per year	Around 14	60 to 100 or more
Annual surface reconstruction	Yes	Rarely, if ever
Soil profile	Heavy engineered loam	Whatever the site happened to have
Height of cut in season	8mm	Commonly 10 to 15mm
Mowing frequency in season	Daily	Weekly to twice weekly
Dedicated staff	Full-time specialists plus a seasonal team	Often volunteers

A club court is asked to do the opposite job: survive a whole summer of members playing on it, on a budget that would not cover a fortnight at SW19. That is why club courts are cut longer, why they play higher and slower, and why the grass season for ordinary players is so compressed — a point explored in our guide to why the grass-court season is short, and in practical terms for anyone hunting somewhere to play in our overview of grass tennis clubs in England.

None of that is a criticism of club groundsmanship. A well-kept club court on a decent soil is one of the real pleasures of an English summer. It is simply a different object, produced under different constraints, and holding it to a televised standard helps nobody.

What the weather does, and the limits of control

For all the measurement, the courts are outdoors and English weather is what it is.

A dry, hot spell firms the profile and dries the leaf. The court plays faster, the bounce gets lower, and the sward comes under stress, so irrigation becomes a constant balancing act between keeping the grass alive and keeping the surface firm. A cool, damp fortnight does the reverse. The grass grows faster and needs cutting more urgently, the profile holds moisture, the bounce sits up, and the surface is more prone to tearing under a sliding foot.

Humidity affects the ball rather than the court. A tennis ball in humid air takes on moisture, gets heavier and comes through slower, which is part of why a match under a closed roof in conditioned dry air can feel quicker than the same match would have felt outdoors in the drizzle that caused the closure. Players notice this immediately and commentators often ascribe it to the court. It is mostly the air.

There is a limit to what any of this can be engineered away, and it deserves saying. The grounds team can make eighteen courts consistent with each other on a given day, and they do. They cannot make the second Thursday of a wet year play like the second Thursday of a dry one, and they have never claimed to. Grass is a crop, the weather is the weather, and that variability is not a defect in the preparation — it is the thing that makes grass-court tennis a distinct discipline rather than a hard-court event played on green paint. The rest of these guides are collected on our England sport hub, and the wider tennis section covers the game beyond SW19.