There are two reasons for covering greens turf during the winter months in the northern climate of the U.S.
1) To protect the turf from cold, dry winter winds.
2) To help prevent the forma on of ice on the greens surface.
But, not all cultivars on our northern greens are the same… some need extra protec on and some actually benefit with no protection.
The most susceptible turf species to winter damage is Poa Annua (poa). Poa plants are annual (some mes bi-annual) and, thus tend to be weak in both summer as well as winter extremes.
Poa lacks ability as to harden itself o for the winter; without an insulating snow cover cold wind will easily desiccate (even kill).
Poa is only able to survive 30-60 days under a solid ice cover.
Unfortunately, most greens on older courses (including most of our New England courses) are predominantly poa. During the winter months leaving these predominantly poa greens uncovered can be a risky endeavor.
Covers in the winter are important for the protection of poa.
But, newer courses, especially in those in the northern climate, have been constructed and seeded with deep rooted bent grasses. Bent grass is extremely tolerant to cold temperatures, can survive 90 to 120 days under solid ice and, best of all, provides a true fast putting surface throughout the golf season.
Courses with predominantly bent grass greens (including The Oaks) have built in protection against the extreme temperatures of both summer and winter. Seldom is the bent grass on greens impacted by winter injury and turf loss.
Most northern er U.S. courses, with predominantly bent grass greens, do not use covers on greens. In fact, one of the best tools in maintaining the long-term integrity of bent grass greens (during the growing season it’s inevitable that bent grass greens become infested with some poa) is exposing small amounts of Poa to winter kill.
This natural ability to selectively kill the undesired grass from a bent grass pu ng surface becomes a long-term investment in the protection of the original seeding.
Poa Anna – Cover in winter.
Bent Grass – Do not cover in winter.
First of all, great job this year, as usual, our greens at Candia Woods and The Oaks are some of the best in New England!
My next 2 questions have to do with bent vs Bermuda grass. I play quite a bit at Pinehurst, and they have been systematically replacing all of the bent greens with UltraDwarf Bermuda. They have done #1, 2, 3, 5, 6, and 8. I notice that they cover the greens every night once the weather gets cold and there is any chance of a frost! Is that because Bermuda grass is very sensitive to cold? During the summer, the bent greens on #4, 7, and 9, are typically in rough shape. Is it the heat, humidity, or both that is tough on bent grass greens in the South?
Thank you, our team appreciates your comments.
On the Bermuda grass, the Ultra Dwarf greens would have limited cold protection so covering them when night time freezing temperatures are predicted makes sense especially if you’re Pinehurst and you have unlimited resources. I think the need for covers in the Transition Zone is not so much to keep the cold out but the warmth of the soil in.
It’s the combination of heat and humidity, very high humidity does the most damage to bent greens in the south. Bent likes cool moist conditions and can handle 90 degree temp on a regular basis. It’s the night time temps of the soil in the Transition Zone where the roots take the first hit, that you don’t see. By the time you start treating the surface issues, most of the damage has been done. The bent needs to transpire or evaporate water on a regular basis, and with high temps/humidity, the plant cannot lose enough of it’s water or cool itself through this transpiration process. That’s why its easier to grow bent in Arizona than it is in Florida.
I hope this answers your questions.