Frosted: Winter's calling card

First the frost, then the snow. — looseends/Flickr

Falling temperatures, biting winds and the first snowfall should be enough to remind you that, wishful thinking aside, winter will soon have its way with us.

As you button up your coat and pull on your gloves, you might imagine that there’s nothing good about the season of frost and cold. From a gardener’s point of view, you would be wrong.

Just as we need sleep to recharge body and soul, plants of our climate are programmed to slip into a period of rest we call dormancy. If you want continuous growth, my chilly friends, you’ll have to move to a lower latitude — and there would be trade-offs.

In tropical and subtropical locations, the weeds never die, the bugs never cease and the gardener gets no reprieve. Moreover, you’d be doing without a host of beloved plants that need a prolonged period of cold to trigger flowering, daffodils and lilacs, to name two.

There are few experiences that fail to yield some fresh insights, and a blast of hard cold is no exception. This is an excellent time to learn more about the lay of your land, to mentally map the cold spots where frost damage is likely and the warmer micro-climates that offer plants a little more protection.

You might think that the coldest places in any yard are the ones most exposed — sites at the top of a hill, open to the wind and weather. Actually, the opposite is true.

Cold air, being denser than warm, flows invisibly across the terrain and seeks out the low-lying areas of the garden. Cold, still air can be trapped by fences, hedges or thick evergreen shrubs creating “frost pockets.”

The place identified as the coldest location in New Jersey is instructive. On average, the chilliest spot in the state is High Point in the far northwest, a rocky bluff that at 1,803 is the state's highest elevation.

Frost crystals, up close. — myri_bonnie/Flickr

But the lowest daily temperatures, the deepest plunges, are consistently recorded at Hainesville, a small burg that sits not high in the hills but down in a glacier-carved valley in the Kittatinny Mountains. Picture the cold like a dense sort of fog, flowing into this hollow and settling in, sending the thermometer down, down, down — to 32 degrees below zero in January of 1994, a record that hasn't been broken since.

In your yard, it's the low spot where the landscape dips down to that stone retaining wall or band of yews that is your own private Hainesville. Any barrier that prevents cold air from flowing lower still will accentuate the affect. Although it's counter-intuitive, a breeze helps move the coldest air along — which is why some dedicated growers trying to prolong the growing season will station a fan in the garden to blow off a killing frost.

Conversely, anything that remains warmer than surrounding air can provide a measure of protection. Plants tucked up against your house will enjoy the protection of that expensive heat leaking out from even the tightest modern construction.

Although it can be a slippery nuisance, there's no better protection for plants than a covering of snow, which insulates the ground like a thermal blanket. Minute air pockets in the snow keep the ground warmer than it would otherwise be and prevent cycles of freezing and thawing that can heave roots near the surface right out of the ground. Think of snow as temporary mulch that spreads itself and melts away without costing you a penny.

When you walk around your yard, be alert for shallow-rooted perennials like mums and daisies that may have been forced from the earth. If you can, tamp them back in; if you can't because the ground is rock-hard, a few handfuls of mulch or leaves might preserve them until you can do a better job.

While you're at it, have a look at evergreens and woody shrubs that may capture dense, heavy snow that can split them in two. It's not a bad idea to loosely tie them up to prevent them from splaying open. If you don't get to it, take a broom outside after a wet snow and gently knock the accumulation from your shrubbery before it causes branch stress or permanent deformity.

Be careful with the de-icing salts, too, since these can persist in the soil and damage plant roots. You might lay in some kitty litter, sand or finely crushed "dirty" stone sold as underlayment for patio paving. These do plants no harm.

Winter can be cruel and the cold no fun, but like all things in nature, nothing lasts forever. Defend yourself and your garden from the season's sharp bite, but think spring. It will be here before you know it.