Frost Delays

Tee Off With Joe

As we break out from winter, a dreaded phrase comes back to life: “Frost Delay.” I can assure you I hate frost delays MORE than any golfer. Not only is the turf grass that I agonize over at risk, but the golfers I aim to please are frustrated.

First, I want to explain more about frost and when it occurs. Frost is the moisture from the air coming in contact with a surface that is below freezing, thus forming ice crystals on that surface. Many factors can influence the formation or lack of formation of frost. For example, clouds and wind are two reasons that frost may not form. Conversely, a clear sky and cold soil can both aid frost development. Tree cover can prevent frost, while an open area is perfect for frost to set in. There are also different stages or severity of frost. A light frost forms only on the upper leaf tissue of the plant, furthest away from the soil. Light frosts usually occur when air and soil temperatures are warmer, like later in spring or early fall. Damage from a light frost can still be significant and very unsightly. This type of frost also does not usually form on shorter mowed surfaces such as greens or tees because they are closer to the soil, which is warm enough to prevent frost from forming. Instead, it is mostly found in rough and sometimes fairways because these plants are further from the warm soil. Heavy frosts can be much more damaging. A heavy frost will cover the entire leaf tissue of the plant and may even reach to the soil surface, freezing the crown of the plant. Freezing of the crown is very dangerous for the plant. The crown is the most important growing point of the plant- any damage to this part from pressure and the entire plant will die. Not only does a heavy frost cover most or all of the outer surface of the plant, often times the water within the cells of the plant will freeze as well. Again, this is potentially fatal to the plant. When weight is applied to the frozen cells they are punctured, explode and the plant dies.

Both light and heavy frosts can occur in one area and not another. For example it is possible to have a frost at the golf course but not at your house because of different environmental factors at each location. Another aspect to keep in mind is that frost can occur when the ambient air temperature is above 32 degrees F. Outside ambient air temperature is measured approximately 2 meters above ground, therefore any air below that height may be colder and form frost on the plant. Also, the soil temperature can influence the air temperature just above the surface, cooling the air below what may be measured and reported as the current temperature. So the thermometer in your car may say 35 degrees F but that can be vastly different than what is happening near soil level on a green in an open area.

One final thought about the formation of frost has to do with when frost forms. If the sun warms the earth all day, then the earth begins to cool at night, starting when the sun goes down. The earth then cools gradually from sunset through the night. Following this logic, the coldest part of the night/morning is just before the sun comes back up to begin warming the earth again. Therefore, frost will be its heaviest, or “set in” just before sunrise. This again can be deceiving to golfers because they may leave their house before sunrise to get that first tee time, see no frost, and arrive at the course and see a frost delay.

With all that being said, many still wonder what the actual risks are to a plant from frost. As mentioned above, the risk to the plant is death. When weight is applied to the frozen plant and the cells are crushed the plant will die. The density of turf grass plants means that weight is never applied to only a single plant, therefore many plants die and what is left is the mark from where the weight was applied. The most recognizable example of this is footprints. People walk across a frost covered green and every one of their footprints is visible. However, plants can become hardened off against frost damage. Sometimes, stepping on a frost covered plant does nothing at all. This means that the most difficult piece of the puzzle is there is no way to accurately know when a plant will die from frost damage. Therefore, to be on the safe side, light or heavy frost, springtime or the fall, play must be held back.

There are some things that turf managers can do to combat or reduce frost. The most common tool is water. By turning the irrigation heads, frost can be melted from the plant. Because the irrigation water is above freezing, it is warmer than the frost on the plant and thus it melts the frost. However, water applied too early will melt the frost temporarily but then re-freeze because the surrounding temperature is still too cold.  However, probably the greatest tool we have is communicating with the golfers. By educating golfers on frost and its risks, it can mitigate some of the frustration that frost delays cause.

Frost delays are not going anywhere soon. But with some patience, and an increased understanding of the science behind frost, maybe the future delays won’t be as difficult for any of us.