The resent cold snap has caught many of us by surprise. With the cooler weather upon us, it’s now time to look into what should be done to protect your landscape plants should a freeze present itself. There are certain precautions one can take to minimize frost and freeze damage.
First, use only thoroughly hardy plants in the basic part of your landscape such as shade trees, screens and foundation plantings. Use the more tender plants only as fillers, or in secondary places (entryways, display plants or in borders).
Become familiar with your garden’s micro-climate. Observe which areas are warm and which are cool. Recognize danger areas such as stretches of open ground exposed to the sky on all sides, particularly to the north sky.
Plants in shallow or in low enclosed areas where cold air is held motionless are also in danger. The cold air will tend to settle in these areas with poor air drainage and cause more damage.
Tender plants are safest planted under overhanging eaves, lath structures or under tree branches. South-facing walls absorb heat during the day and radiate it at night, warming nearby plants.
The most ideal location of all is a south-facing wall with an overhang. Avoid placing tender plants such as fig ivy, camellias, bougainvillea or hibiscus on a north exposure. Cold north winds will take their toll.
Condition plants in preparation of future frost. Taper off nitrogen feeding in late summer and early fall to slow growth and permit wood to harden. Plants in a state of active growth are more vulnerable to freeze damage and less hardy. Reducing water will help harden growth, but keep soil moist at the onset of frost because a moist soil holds and releases more heat than dry soil.
Know how to recognize the signs of approaching frost. Knowing a frost is at hand will give you the advantage in preparing for it. Still air, absence of cloud cover, low humidity, and low temperature (45 degrees or less at 10:00 p.m.), set the stage for a possible frost.
If you notice these signs at bedtime, take steps to get tender container plants inside or under protection of a porch roof or in the garage. Burlap or plastic covers over stakes or frames will do a good job, but make sure the cover does not touch the foliage. Always go out the next day after temperatures rise to uncover the plants.
If plants have been damaged by frost or freeze, do not be in a hurry to prune them. Premature pruning may stimulate new tender growth that will be nipped by later cold. Wait to prune until early spring.
In cases of really severe cold weather when the temperature falls below 20 degrees, the less hardy plants may not make it regardless of your precautions. Even the more hardy plants may be injured.
The most sensible way to protect plants from severe freeze is to attempt to protect their roots by mounding or mulching. If the roots survive, sometimes the plant can be salvaged and new top growth will develop. Use grass clippings, straw, bark mulch or leaf mold, and cover the roots to a depth of four to six inches. Broad-leafed evergreens may be hardy to cold, but suffer wind-burn and sunburn when low temperatures, strong sun and cold, drying winds combine forces. Protect with burlap or lath shelters on the windward side. But above all, keep evergreens watered through the fall and winter to reduce leaf burn.
