1/16/2025 - By Harrell's

Well, it’s officially winter. The day lengths are noticeably shorter as the kids are coming home from playing outside much earlier due to the streetlights coming on sooner (do kids still do this?). While winter affords time with family and loved ones, playoff football, and for some time to reset before the oncoming growing season; winterkill is a huge focus for ultra-dwarf bermudagrass turf managers.

Winterkill and Greens Covers

One item that is often discussed, debated, and implemented throughout these regions to aide in winterkill prevention is the use of covers during excessively cold periods. It won’t be long before agronomy teams look like carney tent or sailboat crews as they begin dragging greens covers out to protect the club’s investment on the coldest of days. Some covers will stay on for days, some will be installed and removed daily, either way, this activity is often contested and debated as it impacts club operations and staff hours.

As the use of ultra-dwarf bermudagrass has moved further north, the data and research available regarding covering greens have increased significantly. The USGA and universities throughout the southeast have researched the use of greens covers to help offset negative agronomic impacts such as winterkill, as well as helping to manage labor inputs and revenue impacts more efficiently. While some of the thoughts can be debated from location to location, the use of greens covers is an insurance policy for clubs to implement during winter months.

Research on Preventing Winterkill

Based on a review of recent research, there are a few key points to help protect ultra-dwarf bermudagrass greens from the negative effects of winter, including winterkill.

Manage Soil Moisture to Prevent Winter Desiccation and Turf Decline

Research supports the use of wetting agents before the onset of wintry weather and throughout the winter (DeBoer et al. 2020). These products have a positive impact on ensuring adequate and uniform moisture levels, reducing the risk of turf injury during cold weather.

Use a Moisture Meter

These tools have changed the way moisture is more accurately managed in all turf types. They are critical for winter ultra-dwarf management when the turf is already off-color due to the stress from winter temperatures. Take the subjectivity out of moisture management and set a volumetric water content percent baseline for your greens.

Remember that even though it is cold, winter weather is often accompanied by high winds and low humidity. These conditions can cause the root zones to dry down quickly. Winter desiccation often is the primary culprit of poor spring transitions.

Manage Winter Shade

The day lengths are already short. Additional reduction in sunlight can reduce potential photosynthesis while further lowering soil temperatures and the ability of soil to re-warm during daylight hours; thus, increasing the turf’s susceptibility to winter damage.

Use Covers to Protect Your Ultra-Dwarf Greens

Set the temperature. Research suggests that courses that regularly experience temperatures 25 degrees Fahrenheit or below should strongly consider the use of turf covers (Goatley et al. 2007). The USGA concludes that courses that have used this as a guideline have performed well.

Pick a cover. Research from universities suggests that there isn’t a statistical difference in results from the various types of greens cover materials; thus, the material selection should be made based on the efficiency of use for staff members.

Consider establishing an air gap between the turf cover and the surface of the green, especially during severely cold periods when temperatures drop below 15 degrees Fahrenheit. This can be completed with pine straw between the turf cover and the green’s surface. Preliminary research states that this process can increase soil temperatures during excessively cold temperatures. This process can also be implemented selectively on colder, north-facing, or more shaded areas in place of entire greens if desired.

Have a Club Standard Operating Procedure

Covering greens is a labor-intensive process that also impacts the revenue stream of the club. Course closures are often needed to complete the installation and removal of greens covers. Additionally, extended closure periods may be needed during longer periods of extreme weather to provide proper protection. Work with your club operations to establish a standard operating procedure for covering greens. An SOP will help establish the facts and eliminate the emotion when deciding to close and cover the club’s greens.

•  If you are looking for a template for a SOP for greens covering, an example is included below.

Connect With Your Harrell’s Rep to Learn More

Regardless of your location, winter weather will be sure to throw curve balls at turf managers. What strategy will you implement to ensure your turf transitions smoothly in the spring? Plan the work, work the plan, connect with your local Harrell’s Rep to get started. We’re here to help.

Golf Course SOP Template

Winter Inclement Weather Greens Covering and Course Closure

I. The Golf Course Superintendent will monitor weather conditions and forecasts and alert the Golf Professional on duty concerning possible and scheduled upcoming Greens Covering events. Notice may be provided to the Golf Professionals as early as Seven (7) Days in advance of covering the event. However, if weather forecasts fluctuate, the Golf Course Superintendent may alert the Golf Professional on duty with minimal notice, on the day of a covering event.

II. The Golf Professional on duty will work with the Golf Superintendent on duty regarding tee closures to accommodate covering the golf course greens.

•  Once a covering event has been forecasted, the professional on duty will work with the scheduled tee times to allow the Agronomy staff adequate time to cover the greens. Closing of the tee may vary depending on scheduled levels of golf.
•  The golf shop will monitor the pace of play to ensure the golf course is clear of golfers at dusk.
•  The Agronomy Department and Golf Course Superintendent will stay connected with the golf shop concerning the availability of Golf Holes so they can be covered without affecting golf play.

III. GOLF COURSE GREENS WILL BE COVERED UNDER FOLLOWING CONDITIONS:

 Overnight Temperatures will remain at or below 25 degrees for 4 hours or more.
•  Green Covers will be removed from greens only if forecasted temperatures call for more than four (4) hours of temperatures exceeding 40 degrees, OTHERWISE, THE GOLF COURSE GREENS WILL REMAIN CLOSED FOR THE DAY.
•  If the forecast elevated temperature of 40 degrees is met, Agronomy will begin removing tarps once the morning temperatures reach 40 degrees or the frost has broken.

References

DeBoer, EJ, DE Karcher, MD Richardson. 2020. Wetting agents for winter turf protection. https://gcmonline.com/course/environment/news/fall-wetting-agent-application-turfgrass#:~:text=A%20late%2Dfall%20application%20of%20a%20wetting%20agent%20can%20help,are%20not%20irrigated%20in%20winter. Accessed December 2024.

Goatley, J.M., P. Sneed, V.L. Maddox, B.R. Stewart, D.W. Wells and H.W. Philley. 2007. Turf covers for winter protection of bermudagrass golf greens. Applied Turfgrass Science 4(1):1-10 (https://doi.org/10.1094/ATS-2007-0423-01-RS).