Frost

The formation of ice crystals on leaves of grasses and plants. The ground or surface temperature will be at 0°C or below for frost to form. Where a lawn or sports turf surface has frost present then it is best to not walk on the area until the frost has gone from the leaves as well as within the soil. If grass is walked on during a hard frost then it is possible to crush the grass leaves, turning then a blackish colour. In addition, if the frost is thawing then the point where the thawing surface interacts with a still icy lower layer will be weak and if walked on this can typically result in shearing or tearing of roots.