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Anyone for Tennis – Research?
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Welcome to The Turf Zone podcast. This episode features the article “Anyone for Tennis – Research?” written by Dr. Scott Ebdon – Emeritus Professor, University of Massachusetts – Amherst and Mike Buras – former Director of Grounds, Longwood Cricket Club, Chestnut Hill, MA
For accompanying tables, graphs, photos and references see the Summer 2026 issue of New England Blade magazine available on www.theturfzone.com
Tennis on Grass – USA
There are 26 million tennis players in the USA, and these numbers have increased by 33% since the COVID years. Less than 1% of tennis courts are grass with most grass courts found in the Northeast region.
Sports grass managers may not truly appreciate the intensity of traffic (wear) observed along grass court baselines. Previous research has shown that the intensity of traffic along court baselines is 6 times the intensity of elite soccer (Newell and Wood, 2000).
The term “pace”’ in tennis is the speed that tennis play (and the ball) moves and is determined largely by the vertical height of the bounce off the court. The higher the vertical bounce, the slower the play. Slower play is preferred by players. Pace on grass is notoriously fast.
Grass Tennis Research – UMass Amherst
In 2016 several studies were initiated at the Troll Turf Research Center (South Deerfield, MA). The two main objectives were (i) wear tolerance or carrying capacity (hours of play) along court baselines and (ii) the factors affecting tennis pace.
Eight turfgrass species were compared within each of three single courts (planted as replicates). The eight species-cultivars were shown to have superior wear tolerance. The grasses were planted as pure stands. The Troll Center was open to the public for daily play from 2017 to 2024. Play averaged 125 hours during the tennis season (June 1 to September 1).
Grass Court Maintenance
The maintenance of grass courts at the Troll Center used a daily mowing schedule at 5/16 inches (clippings collected), rolling 4 to 6 times per week with a 2,200 lb. roller, sprayable fertilizers (spoon-feeding) on a 2 to 3-week schedule to apply 3.15 lb. N per 1,000 ft² per season, and sprayable (preventative) fungicides. Heavy rolling and daily mowing was especially important to promoting consistent (uniform) tennis ball bounce and play. Weekly measurements were scheduled after significant soil drying – irrigation was used sparingly to prevent any visible turfgrass dehydration.
Tennis Ball Bounce
The rules for measuring vertical ball bounce were established in 1925 (Miller, 2006) and are outlined in Table 2. Higher ball bounce (slower pace) on a tennis surface is due to greater velocity of the ball in the vertical direction. Soft grass absorbs more energy indicated by greater surface deformation – less energy is available for ball bounce in the vertical direction.
Ball bounce must be uniform-consistent and representative of ball bounce across the entire court surface.
Measurements of Hardness – 0.5-kg Clegg
Hardness is measured with the Clegg impact soil tester and has been used on grass courts since the mid-1980s (Holmes and Bell, 1986) and used currently to predict tennis ball bounce (Ebdon et al., 2025). Surface hardness is measured as gravities (g, also referred to as “Gmax” in the literature).
The energy of impact using the 0.5-kg Clegg (30 cm drop height) conforms closest to the tennis ball bounce test. The 0.5-kg Clegg and the tennis ball bounce test are highly correlated compared to heavier Clegg devices used in sport grass (2.25-kg Clegg, 45 cm drop height) or devices used in golf (USGA TruFirm, 1.95-kg, 48 cm drop height). These heavier devices are not as effective for tennis (Ebdon et al., 2025).
Tennis Ball Bounce (BB) and Clegg Hardness – Courts Under Play
Over the course of this 10-year study some 3,200-ball bounce impacts and hardness measurements were taken on various grass court surfaces. The results presented in Table 3 for the different surfaces are comparable because accepted (standard) methods were used.
Wimbledon center court (perennial ryegrass courts) for the 2011 Championship were bouncing at 52 inches or 91% of concrete. All of the perennial ryegrass courts at the Troll Center and the Tennis HOF satisfied the minimum standard of 70% concrete. Kentucky bluegrass courts at the Troll Center were bouncing near 70% (69%) of concrete.
The fine leaf fescue mixture was among the highest in BB averaging 76% of concrete. This species, however, is the least tolerant of tennis traffic, discussed below. Traditional golf species such as creeping bentgrass-Poa grass courts were bouncing below the 70 to 80% concrete standard.
Tennis Ball Bounce – Uniformity
Consistent BB across the tennis surface is important for uniform play. Smooth-hard concrete is the most unform and consistent surface. All other surfaces are compared to the BB consistency of smooth concrete. The concrete surface has an average hardness of 865 g compared to Wimbledon hardness of 260 g. Smooth concrete has a BB uniformity of “1.” Wimbledon BB uniformity for the 2011 Championship was measured at “2.1” – twice the variability of concrete.
Player perception of BB uniformity (relative to concrete) is interpretated as “an odd bounce.” One consistent trend observed in Table 3 indicates that increasing surface hardness promotes uniform ball bounce and the chances for odd bounces decrease. Therefore, selecting species such as perennial ryegrass affording harder surfaces and higher BB (slower play) have a tendency for more consistent (uniform) play. Many bentgrass courts (or greens) and Poa annua courts that are prone to thatch are the least consistent surfaces with BB uniformity of “7” and higher relative to concrete.
Court Hardness to Satisfy Standards – 70 to 80% Concrete
Research at the Troll Center indicated 150 to 170 g of surface hardness is needed for tennis balls to bounce to standards – 70% (40 inches) to 80% of concrete (46 inches) (Ebdon et al., 2025). Tennis BB of 80% concrete is not easy to achieve. To that end, surface soil moisture is extremely important, discussed below.
For the 2011 Wimbledon Grass Court Championship, 100% of all BB impacts were at 80% of concrete. At the Troll Center and the Tennis HOF approximately 16 to 18% of all impacts satisfied the 80% concrete standard. Following uniform drying of the Wimbledon soil, 24% of all BB impacts exceeded the minimum standard for concrete. Tennis play at Wimbledon is ideal for the Grass Court Championships because of the slow pace and consistent BB.
Tennis Ball Bounce – Surface Soil Moisture
Soil moisture using TDR (3-inch probes) was measured weekly during the tennis season concurrently with surface hardness and ball bounce. In tennis, the ball bounce test is a surface phenomenon. This is the main reason why the low energy impact of the light weight (0.5-kg) Clegg is more effective in predicting tennis ball bounce than heavier devices (2.25-kg Clegg or 1.95-kg TruFirm) (Ebdon et al., 2025). Similarly, longer TDR (5-inch) rods are not as effective as 3-inch probes – it is the immediate surface moisture that matters in tennis ball bounce.
Soil drying will promote harder surfaces but this depends on the soil texture and the mineralogy (clay content) of the soil. Table 5 compares soil drying and surface hardness between the Troll Center and Wimbledon soils.
The gains in surface hardness from 38% soil drying are very different between the Troll Center soil (silt loam, 12% clay) and Wimbledon soil (sandy clay loam, 23% clay). At the same soil moisture deficit (38% soil drying), 60% greater surface hardness is observed on Wimbledon soil (77 g increase – Wimbledon vs. 48 g increase – Troll Center). The Troll silt loam increases in hardness only 3.2 g with 1% soil drying compared to 5.5 g with 1% drying for Wimbledon soil. For most soils it is believed that soil drying is more important in providing a hard tennis surface than soil compaction by rolling.
Any natural soil drying will promote higher ball bounce. Recent research indicates that soil drying to 40% soil moisture depletion causes minimal turf dehydration with fine textured soils (Bruan et al., 2022). Figure 2 presents 1122 pairs of vertical ball bounces and soil moisture (3-inch TDR) measured on Troll Center perennial ryegrass courts during a 17-week period. Prior to soil drying (week 1), tennis ball bounce was below standards (66% of concrete) while after progressive soil drying (week 17) ball bounce exceeded standards (83% concrete).
Species Wear Tolerance – Carrying Capacity
Grass cover after tennis play ended is presented in Table 6 along with the carrying capacity (hours of play) to wear baselines to 70% grass cover. Following 2-years of study perennial ryegrass and Kentucky bluegrass exhibited significantly better wear tolerance (≥ 65% grass cover) and greater carrying capacity (≥ 70 hrs. of play to 70% cover) compared to bentgrass and fine fescue species.
Traditional golf species (bentgrass) are comparatively less tolerant of tennis traffic compared to improved cultivars of Kentucky bluegrass and perennial ryegrass – providing the cultivars are tolerant of 5/16-inch mowing heights. Of all the species-cultivars tested, the fine fescue mixture was the least tolerant of tennis traffic (24% grass cover) with the lowest carrying capacity (20 hours).
Interestingly, the fine fescue mixture used in the tennis study was the same mixture used on the golf greens at the 2015 US Open (Chambers Bay, WA). This is further evidence as to the intensity of the traffic that is often underestimated in tennis.
The Court Playability
The highest priority should be given to planting wear tolerant grasses adapted to tennis play. Grasses with significantly lower carrying capacity will wear-down faster under the same hours of play. The loss of grass cover during the tennis season has a significant impact on tennis play (pace) and the uniformity (consistency) of ball bounce.
Table 7 summarizes approximately 3000 measurements on perennial ryegrass courts at the Troll Center. Perennial ryegrass represents the most wear tolerant species with the highest capacity for surface hardness for satisfying ball bounce standards – ideal for tennis. All areas of the court satisfied ball bounce standards (≥ 70% of concrete). However, the T-area approached 80% concrete with an average surface hardness of 143 g and BB of 45-inch.
Surface moisture was 4.4% drier at the T-area (less grass – more exposed soil for surface drying). It is the soil drying at the worn T-area and baselines that promotes an increase in hardness and ball bounce under tennis play – consistent with soil drying presented in Table 5. These worn areas will play different (slower) because of the increase in the vertical height of the bounce compared to the less trafficked service box. The soil-water relations presented in Table 7 are consistent with golf greens and sports grass under heavy play (McClements and Baker, 1994; Straw et al., 2017).
What We’ve Learned
Soil drying promotes harder surfaces and the uniformity of ball bounce approaches the uniformity of concrete. At week 1 before soil drying, BB uniformity relative to concrete was “3.7.” At week 17 following soil drying, BB uniformity across all three courts was “2.6” – approaching the BB uniformity of hard courts.
The measured results reported here are consistent with player perceptions. As eight-time Wimbledon Grass Court Champion, Roger Federer, lamented:
“This new, fresh grass, we’re not quite used to it…as you go deeper in the tournament, the grass court becomes more clay-courty, hard-courty with a bit of grass on it…the ball bounces a bit higher”
How fast (low bounce) or slow (high bounce) or consistent (uniform) a grass court plays is dependent on the tolerance of the species-cultivar to traffic and to the properties of the underlying soil and its plant-soil-water relationships.
References
Braun, R. C., Bremer, D. J., Ebdon, J. S., Fry, J. D., & Patton, A. J. (2022). Review of cool-season turfgrass water use and requirements: I. Evapotranspiration and responses to deficit irrigation. Crop Science, 62, 1661–1684. https://doi.org/10.1002/csc2.20791
Ebdon, J. S., Lu, J., and DaCosta, M. (2025). Comparison of Clegg and TruFirm surface hardness for predicting tennis ball bounce standards on grass courts under match play. Crop Science, 65, e70109. https://doi.org/10.1002/csc2.70109
Ebdon J.S., James I., DaCosta M., and Lu J. (2020). Interspecific comparisons of C3 turfgrass for tennis use: I. Wear tolerance and carrying capacity under actual match play. CropScience. 2021;61:750–762. https://doi.org/10.1002/csc2.20270
Holmes, G., and Bell, M. J. (1986). Playing surface hardness and tennis ball rebound resilience. Journal of the Sports Turf Research Institute, 62, 207–210.
ITF. (2019). Approved tennis balls, classified surfaces, and recognized courts: A guide to products and test methods. International Tennis Federation. https://www.itftennis.com/media/2016/2019-itf-technical-booklet.pdf
McClements, I., and S. W. Baker. (1994). The playing quality of natural turf hockey pitches. J. Sports Turf Res. Inst. 70:p. 13-28.
Miller, S. (2006). Modern tennis rackets, balls, and surfaces. British Journal of Sports Medicine, 40, 401–405. https://doi.org/10.1136/ bjsm.2005.023283 Medicine, 40, 401–405. https://doi.org/10.1136/bjsm.2005.023283
Newell, A. J., and Wood, A. D. (2000). Selection of grass species, cultivars and mixtures for lawn tennis. Journal of Turfgrass Science, 76,53–65.
Straw, C. M., Bowling, W. J., and Henry, G. M. (2017). Rainfall versus irrigation influences penetration resistance and surface hardness on a recreational sports field. Int. Turfgrass Soc. Res. J. 13: p. 1-5.
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