The Cold Hard Facts about Frost on Turfgrass
Winter has arrived in most areas of the country. If you happen to live in an area where temperatures fall to around and/or below freezing (32 F), then there are some turfgrass “things” that you need to pay attention to as preventative measures so no turfgrass damage and loss is noticed in the spring.
One of the earliest signs of old man winter that show up on turfgrass is frost. Frost is an interesting process that occurs on clear, cold nights. Frost forms when the turfgrass plants re-radiate or give heat off to the atmosphere (exothermic) causing a “cooling” effect of the turfgrass leaves. If the leaf temperature is lower (cooler) than the air temperature, then moisture from the atmosphere will condense on the turfgrass leaf (dew). Frost then forms when the temperature of the leaf drops below freezing (32 F) and the water on leaf freezes. Frost will occur even if the air temperature is slightly above freezing.
Frost formation on turfgrass leaves
Frost doesn’t form as readily under cloudy conditions because the clouds reflect, or absorb and re-radiate the heat energy back towards the Earth’s surface. Thus, the turfgrass plants receive heat from this process preventing frost from forming. Wind will also prevent the formation of frost by air convection and the mixing of air from the atmosphere and the air closest to the leaf surface by “buffering” the leaf temperature drop and promotes evaporation of the water condensate on the leaf surfaces.
Frost normally forms early in the morning before sunrise as this is when the leaf temperature is at its coolest. Frost may continue to form for a brief period after daylight due to the low angles of the sunlight during winter solstice preventing light from directly reaching the turfgrass leaves.
Frost damage to turfgrass stand
Frost does not cause damage to the turfgrass itself, but rather turfgrass damage occurs when traffic occurs on these frost affected areas. The turfgrass damage is normally superficial. This is not to say that traffic should be allowed on frost affected turfgrass. If traffic occurs on frost affected turfgrass, whether it is foot or mechanical, turfgrass damage is caused by the crushing of the turfgrass leaves and the ice crystals rupturing plant cells. Initially, the symptoms will appear as a purplish to black coloration of the leaves progressing to a brownish “straw” color. If the traffic is concentrated and damage occurs to the turfgrass crown, then recovery may not occur.
Frost damage from golf cart traffic
Of course, golfers do not like or understand frost delays. It is very important that we as turfgrass managers communicate to golfers and members as to why and how frost can damage turfgrass if traffic is allowed. Another important factor to keep in mind and communicate is that a foursome of golfers typically takes several hundred steps on each green.
Foot traffic from one foursome of golfers on a golf green
So, frost delays are a requirement to prevent turfgrass damage from occurring. By allowing even a few golfers to play when frost is present can be very damaging to the greens as well as other turfgrass areas on the golf course. It is impossible to predict when frost is going to occur or when turfgrass damage is going to occur from frost, so the decision to control or prevent traffic from going on to the golf course must be made conservatively to protect the turfgrass and its health. Given this information, do not feel guilty any longer proclaiming a frost delay and make certain that the delay is sufficient that frost will be completely melted at the time play is allowed to occur on the golf course.
Now, we can discuss the one benefit of frost – colder beer.
Golf Course Superintendent
Tampa Palms GCC