Cold nights, hard frost

Dorothy Cook/Flickr

Dorothy Cook/Flickr

Fog may creep in harmlessly on little cat feet, as the poet says, but frost is more like Mac the Knife, stealthy and brutal.

I know for certain the night it first snuck into my garden. By morning’s light, the outdoor containers of impatiens and coleus were misshapen mounds of withered foliage and the cannas’ blackened leaves were as limp as flags on a windless day.

The first hard frost is dramatic punctuation to the growing season, an exclamation point rather than a period. Every cold-sensitive plant is cut down, its water-saturated cells frozen and burst. For this damage, there is no cure.

Like fog, frost is moisture suspended in the air, but when temperatures fall to 32 degrees or less, it condenses as an icy tracery on plants, grass blades, roofs and car windshields.

It seems intuitive to imagine that the most exposed places – high on a wind-swept slope, for instance – might be the hardest hit. Actually, the opposite is true.

It’s more correct to think of frost as an invisible stream, seeking not the highest point but the lowest. Cold air, being denser than warm, flows down hill and often is trapped in “frost pockets” where fences or hedges prevent its onward movement. Still nights are more lethal than breezy ones.

The best predictor of frost is the dew point, often mentioned in weather forecasts. If the dew point sits at 32 degrees or less, expect a frosting. Clear nights are more likely to bring an icy coating since there are no clouds to prevent an escape into the great beyond of warmth radiating from the ground.

The arrival of frost, like the shift back to Eastern Standard Time should trigger some essential garden chores. Chief among them (since the consequences can be expensive) is shutting off outdoor water taps that don’t have frost-free fittings.

Sprinklers, watering wands and hoses can be damaged as well, so it’s time to round them up. Other, more aesthetic water features also need attention now -- fountains and bird baths should be emptied or winterized.

Frost is the warning bell, but parts of the garden live on. My late-blooming Korean mums, which flowered over the past two weeks, are still in their glory and a few tardy roses cling to their thorny stems. There’s still time to plant spring bulbs, too. In the mid-Atlantic region, prime bulb-burying time is Oct. 1 through Nov. 30.

For all its dangers to plant life, frost can be extremely beautiful, coating every leaf and stem with an ethereal icing that melts away as the morning sun strengthens. From afar, a hillside, meadow or lawn can almost look snow-covered – sparkling and picturesque without the shoveling.

Frost may spell the end of serious gardening but it ushers in the quiet season of falling leaves and nippy nights. To every season, special pleasures. Sneak out in the early morning and see the glitter of frost-spangled world, another one of those free shows courtesy of Mother Nature.

Robbie Sproule/Flickr

Robbie Sproule/Flickr

I can remember as a kid being fascinated by the elegant embroidery of frost on windows, the cold-weather version of fairy dust. Children today don’t grow up with this crystalline artwork so much anymore thanks to double and triple glazed windows and tighter houses.

You can simulate Jack Frost’s handiwork, though, with a crafty formula of two readily available ingredients, Epsom salts and beer:

Mix four heaping tablespoons of Epsom salts in a cup of beer; use a good-sized bowl, since the mixture will foam up. Let it sit for 30 minutes, then swash the solution on your windows with a cloth, as if you were washing them. While the mixture is still wet, go back and daub at it to create an irregular surface.

Within hours, beautiful frost-like crystal patterns will form, looking just as if Jack Frost had come by. Crystals will be fully developed in six to eight hours and can easily be washed off. Don’t bother to clean the windows before you frost, since small particles of dirt and irregularities on the glass give crystals an anchor point from which to grow. The kids will think you’re a magician.