Should you keep off the frosted grass? The answer is yes. Frost will not actually harm lawn grasses, they are completely hardy. But you must keep off the grass while it is actually frosted. If you walk on frosted grass the blades are stiff and when you walk on them you snap them and it kills the foliage. As the grass thaws it usually turns black so you can see where you have been immediately.
Later the foorprints turn yellow as the grass decomposes and sometimes it can be infected with fungal diseases – not very good.
Snow is a problem too. If snow is on the lawn for long it causes snowmould, a fungal disease. And when you walk on the snow and compact it, it turns to ice and takes a lot longer to melt so you may end up with yellow footprints just like you create when walking on frosty lawns.
And the photos above were taken in the garden. I hate it but the cat, who is content to sleep quietly all night, jumps on the bed to wake me so I take her out first thing in the morning. So she has to be escorted round the garden and, though I try to avoid the grass, it is not always possible. At least it provided me with ‘homegrown’ photos.