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Turf Cover Effects on Putting Green Winter Temperature Spring Green-up and Growth

Study at Penn State University by Dr. G. W. Hamilton, Jr. and R. B. Raley. Published in 2004.

February 14, 2023

before and after results unveiled after growth cover research study


Various types of greens covers have been developed to protect golf course putting greens from different types of winter kill and to hasten spring green-up and growth. Cover materials range from geo-textile fabrics to solid or woven polypropylene or solid polypropylene sheets. Covers are usually placed on putting greens just prior to the onset of winter conditions and removed a week or two after spring green-up has started.

The objective of the study was to evaluate CoverSports' polypropylene winter cover's effect on winter turfgrass canopy temperature, spring green­up, and growth.

Materials and Methods

This study was conducted at the Valentine Turfgrass Research Center in University Park, PA. The study was conducted on a "push-up" style putting green and the turf was a mixture of creeping bentgrass and annual bluegrass maintained at 0.125 inches.

Plots were 2 by 2 feet and treatments were arranged in a randomized complete block design with three replications. Treatments consisted of CoverSports' polypropylene turf cover and an untreated control. Treatments were applied on December 13, 2003 and removed on March 28, 2004. Turf grass canopy temperatures were recorded every four hours with Onset HOBO H8 data loggers and Onset wide range temperature sensors placed within the canopy of turf. Growth was measured by removing clippings (yield) with a 22-inch walk-behind greens mower. Clippings were dried at 60°C for 24 hours and dry weights were recorded. Color was rated visually on a scale of 1-5 with 3 or above considered acceptable color. Yield and color ratings were recorded on March 29, 2004, April 6, 2004, and April 15, 2004.

Yield and color data were statistically analyzed using Analysis of Variance and treatments were separated using Duncan's New Multiple Range Test with p = 0.05.

Results and Discussion

Canopy Temperature

On average, the canopy temperatures of the turf cover were 2°F above the control. For the duration of the experiment, the average temperature of the Turf cover was 34.4°F and 32.1 °F for the untreated control. This increase in average temperature would increase spring green-up and growth in the spring when temperatures would start to increase.

The turf cover treatments also maintained higher minimum temperatures than the untreated control. During all four months of the study, the untreated control had minimum temperatures lower than the turf cover treatments. This restriction of lower temperatures by the turf cover may help prevent certain types of turf grass winter injury such as direct low temperature kill.

Turfgrass color

There was a significant difference in color when the covers were removed in late March. The turf cover treatments had an average color rating of 4, which was well above the acceptable color of 3 .0 and significantly higher than the untreated control rating of 2.5 (Fig. I).

For the next two subsequent ratings, April 6 and April 15, there were no significant differences between the turf cover and the untreated control. Color of the turf cover treatments actually decreased over the two-week period. This was caused by an increase in growth under the covers, and the initial mowing caused some slight scalping. Cold temperatures following the initial mowing slowed growth and restricted the turf cover treatment turf to outgrow the scalped condition.


There was an obvious visual difference in growth between the turf cover treatment and the untreated control. The turf under the turf cover was taller and slightly thinner than the untreated control turf. Although there was a visual difference, the yield measurements were not statistically different on any of the three rating dates (Fig. 2).


The turf cover treatment did increase canopy temperatures throughout winter and did have improved color when the treatments were removed. The improvement in color for the turf cover treatment lasted less than a week after treatments were removed, and there were no statistical differences in yields of the two treatments.

Future Research

The difficulty in managing covers is deciding when they should be removed and whether or not they should be replaced after initial mowings. Future studies should evaluate various removal times and the advantages or disadvantages of replacing the covers after mowing.


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