Frost mostly occurs when there is little or no wind and clear skies at night and when the overall temperatures have plunged overnight to zero or below. Essentially, the frost is the result of dew freezing on your lawn.
Why is this a problem?
Grass blades move water throughout the length of the plant for nourishment, but when a frost comes, the moisture freezes inside. When the water freezes it expands, rupturing plant cell walls.
A light frost that does not freeze the ground won’t cause severe damage because the grass roots below the soil remain above freezing point. You may see some blade damage but generally the roots often have the chance to heal the damage as the grass will continue to grow.
The frost can freeze the leaf blade and cause significant discolouration – this discolouration is a signal that the frost has damaged the cell walls of the turf.
Before frost hits
Ensure that your lawn is in good overall health so that it is able to tolerate any frost better. Consider applying a fertiliser with increased iron before any frost hit to strengthen your lawn for the months ahead.
Give your grass a deep watering the night before an expected frost. The watering allows moisture to slowly evaporate overnight, causing friction and heat around the grass blades. As the night air drops below freezing, you turf will have a slightly higher temperature from the evaporating heat process, allowing your grass to not reach the freezing temperature that causes plant cell wall damage.
Move the mower blades up 1.5 cms, allowing longer leaves to help shelter grass crowns from frosts.
Avoid mowing right before a frost. Mowing creates a wound on the plant, making it more susceptible to frost damage.
If you’re installing a new lawn talk to your local turf supplier to determine how likely frost is in your area and therefore the best variety of turf.
If frost hits
If the temperature plummets and there’s frost on the lawn, the most important thing to do is to stay off it – if you walk on it you will cause the blades of the grass to break and cause even more damage.
Give your lawn a light watering just before the sun rises to remove any frost from the leaves. This will help to melt the frost more quickly and evenly – and you’ll be less likely to end up with brown patches in your lawn.
Mow only after your lawn begins to grow again and not looking discoloured. Move the mower blades up 1.5 cms, allowing longer leaves to help shelter grass crowns from future frosts.
Wait to fertilise for up to a month after damage since extra nitrogen from frost dehydration can cause more damage.