We’ve had two consecutive heavy frosts at my place this week. They were thick and I could hear the crunch of frozen grass beneath my shoes as I quickly snapped some photos before scooting back inside. Frost, that thin layer of ice that forms on a solid surface, is a sure sign of a cold night.
I’m getting used to frosts since moving to this area. We rarely had them in the built-up area I used to live so it’s taking some adjusting to understand the impact they can have in the garden. The Bureau of Meteorology app has become my best friend!
Learning what ‘frost hardy’ means on a plant label and understanding the effect frosts can have on various plants interests me. When I read that a particular seedling should be planted ‘after the last frost’, it seems a vague instruction. How do you know when that time is?
Local knowledge is the best way to judge but, in my case, I rely on my garden diary. From my records, I can tell that we had our first frost this year in June, unlike the previous three years when frosts arrived in May. My diary records that our last frosts have been in October each year.
So, what is frost and how is it formed?
It occurs when the temperature of the air cools down by loss of heat to the atmosphere. Usually, this happens when there are clear skies overnight and no wind. Lower ground is usually affected first.
Frost can cause ice crystals to form in plant cells and this destroys access to water within the plant’s tissue. The result is black, shrivelled frost-damaged leaves. No one wants that!
There are several ways to help plants survive expected frost. Keep them watered because moist ground stays warmer than dry ground. Mulch around plants for the same reason. In some cases, covering the plants with cloth will help insulate them against the cold. I’ve heard that some gardeners even wrap ceramic pots with bubble wrap to protect them.
So, while I’m snug in my bed covered with quilts, I’ll think of the plants in my garden shivering outside. Hopefully, the actions I have taken will prevent frost damage, yet still provide photo opportunities!