One of the more interesting questions I’ve received from a reader was a simple, one line note that read “From which direction does the frost come?”. On first glance I wondered whether it was a riddle or an odd joke. Did the answer have something to do with the magnetism of the earth or was it simply such a weird thing to ask that I ought to check the envelope for white powder before replying just as succinctly, “The Right”?
Then I stopped fooling around and actually thought about the question. Does frost come from a direction? It’s a fair enough thing to ask, and the answer, strangely enough, is both yes and no. Let me explain.
Whenever I’m asked to describe frost, I suggest that it’s the result of very cold air that behaves similar to a mass of treacle or honey moving across the landscape. There’s no way, of course, that frost comes from a point on the compass, and when I say it comes from The Right, I’m only having a lend. Besides, “frost” is only the visible ice crystals that form as a result of moisture being frozen by cold air, not the air itself. But when the reader’s question is taken literally, the answer is also literal.
Think about it. Cold air is denser than warm air. On clear, still nights during winter, warm air radiates away into the atmosphere, but the heavier, colder air descends and pools at ground level. It rolls down hills. Settles in hollows. Gets trapped against the base of walls and hedges. So, from which direction does the frost come? The answer’s clear: from above.
Now, for the heavenly minded among you, take heed. When I say “from above”, you shouldn’t get too excited. I’ve learnt from bitter experience that frost can wreak havoc in a poorly planned garden, causing one to hurl curses in the direction of hell. My garden experienced an ugly “black frost” in 2007 that saw the temperature drop to about minus ten. It froze the pipes solid for two days and burnt the foliage on 10 metre tall trees as effectively as the fires of Hades itself.
These days, I record every frost the garden experiences. I mark the date of the first and last frosts for the season, watch the weather forecast like a hawk, and measure the minimum temperature each night. I used to record all the details in my diary, but now it all goes into a notebook, alongside details about wind, rainfall and other tidbits about the garden.
This info has come in really handy. I know that our first frost can occur as early as Anzac Day, and the last can be as late as October. Summer vegies get planted later than they did in my Toowoomba garden as a result. I also know that we generally get about 40 frosts per year, about 20-30 of which are light (zero to minus three degrees), 10 are moderate (minus three to five) and a small number of which I categorise as heavy (lower than minus five). I figure that gardening has lots in common with farming, and no farmer worth his or her cabbages would be ignorant to the details of climate and weather.
All this talk about Hades and frost damage might give the impression that frost is some kind of malignant force. Sorry if I’ve given you the wrong impression. Now that I’ve learnt to choose hardy plants, I actually love frost. I welcome its arrival and mourn its passing. Why? The benefits of a good frost far outweigh any problems it might cause.
For one, there is the potential for pest control. A heavy frost is cold enough to kill some fungal spores, insect eggs, overwintering insects and even rodents, so it breaks the pest cycle better than any chemical. A good frost can also freeze moisture in the soil, helping to make it more workable.
And then, there is beauty. Find me a gardener hasn’t stood shivering but transfixed in the thin dawn light, taking in the sheer wonder of their otherwise boring garden transformed into a fantasy land of twinkling ice crystals. You know I’m not a raving fan of formal hedges and topiaries, but I am prepared to admit that nothing looks better on a frosty morning.
For what it’s worth, here’s my advice: use formal features judiciously when planning your garden, and spend the odd winter afternoon keeping them nicely trimmed. Then head inside, put a fresh log on the fire and pray that the morning brings temperatures below freezing point. Finally, the best advice of all: when dawn breaks, head outside in your bare feet, inhale deeply, and marvel at the wonder of frozen dew. Maybe frost does come from above, after all.
First published in the Toowoomba Chronicle 5th June 2010. Photo courtesy Granite Belt Wine and Tourism Inc.
