Cold Weather and Protecting Plants

Bennett Joffrion  |  11/18/2005 1:26:53 AM

As of this writing, we have begun to have a few cold weather days. Lately, we have been receiving really cold weather in late December, January and February. Now is a good time to be prepared and take precautions from low temperatures in the landscape.

Winter damage is caused not only by low temperatures, but also by drying winds that lead to desiccation of plant tissue.

What to do before a Freeze

Move all tender plants (plants killed or severely damaged by temperatures below 32 degrees) in containers and hanging baskets into buildings where the temperature will stay above freezing. If this is not possible, group all container plants in a protected area (like the inside corner of a covered patio), and cover them with plastic. If plants are kept inside for extended periods, make sure they receive as much light as possible.

Water

If it has been dry, thoroughly watering landscape plants before a freeze may reduce the chance of freeze damage. Many times cold weather is accompanied by strong, dry winds. These winds may cause damage by drying plants out, and watering helps to prevent this. Wetting the foliage of plants before a freeze does not, however, provide any cold protection.

There is a freeze protection system used in citrus, but this is a controlled water flow onto the tree.

Mulch

For plants growing in the ground, mulches can help protect them. Use a loose, dry material such as pine straw or leaves. Mulches will protect only what they cover. A mulch at the base of a bird-of-paradise will help the roots, but will provide no added protection to the leaves.

Mulches, then, are best used to protect below-ground parts crowns, or they may be used to completely cover low-growing plants to a depth of about 4 inches. If you use a mulch as a complete cover, leave it on no more than 3 days.

Covers

If plants are not too large, covering them with cardboard or Styrofoam boxes can offer protection. Larger plants can be protected by creating a simple structure and covering it with sheets, quilts or plastic. Be sure the structure holds the covering off the foliage. The cover should extend to the ground; seal with soil or other heavy objects. Plastic covers should be vented or removed on sunny warm days.

These covers will work best for light, quick freezes. For extreme prolonged cold, this is another story.

For treasured plants, you can try providing a heat source under the cover. Extreme care should be used. Most commonly a 100-watt bulb or Christmas tree lights can be placed under the cover with the plant. Be careful the bulb does not come in contact with foliage or the cover material; use outdoor approved extension cords and sockets.

Some plants can be pruned to make them more practical to cover. Hibiscus is a good example. For trees such as citrus that are too large to cover, you may at least wrap the trunk with an insulating material such as foam rubber, pipe wrap or blankets. The top may die, but you may save the rootstock.

What to do after a Freeze

After a freeze is over, check the water needs of plants in containers and in the ground. Remove or vent plastic covers to prevent excessive heat buildup if the day is sunny. Pull mulch back that completely covered low plants.

Delay hard pruning on woody plants until new growth begins in the spring, then you can accurately determine which parts are alive and which are dead. Don’t be too quick to dig up and remove plants that appear to be dead. On occasion, they may eventually resprout from the roots in April or May.

Winter Weed Control

One good winter weed control practice is to apply liquid atrazine in late November or December. The rate is 3 tablespoons per gallon of water and 1 gallon will treat 1,000 sq. ft.

Atrazine has activity on both emerged and non-emerged weeds. It does a really good job on clover, lawn burweed or stickweed and works well on newly germinated annual bluegrass. You can reapply atrazine in early February for a cleanup control.

Read label and apply product correctly. Atrazine can injure landscape plants and trees if applied near their root zones. Stay away from the dripline of trees and shrubs with this herbicide. Many Drake elms have been killed by this.

Question. Can turnip green leaves be eaten?

Answer. Yes. Turnip leaves can be harvested as single leaves picked one at a time or by several cuttings of the tops, taking care to avoid growing points or by cutting all tops at one time.

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