Our last freeze date in Austin Texas is about March 10. Decide now how to protect your plants in case the temperatures dip below freezing. Your plants can be classified as either hardy (able to endure temperatures 32 degrees or below with little or no damage) or tender (will be killed or severely damaged by temperatures of 32 or below). See a list of plants and their cold tolerance temperatures at the end of this article. Tropical plants and warm season annuals are considered tender, however, they will sometimes survive a hard freeze by coming back from their roots. Winter damage to trees and shrubs in the home landscape is not only caused by low temperatures but also can be caused by drying winds that lead to desiccation of plant tissue. Please note, however, that plants do not feel the "wind chill" temperature that we feel, and will therefore not suffer freeze damage from wind chills below freezing when the actual temperature is above freezing.

What to do before a freeze

Water. Thoroughly watering landscape plantings before a freeze may reduce the chance of freeze damage. This will help keep plants from drying out because of strong, dry winds. Furthermore, a well-watered soil will absorb more solar radiation than dry soil, and it will re-radiate the heat during the night. Wetting the foliage of plants before a freeze does not help with cold protection.

Move Inside. Move all tender plants in containers and hanging baskets into buildings where the temperature will stay above freezing, and make sure they get as much light as possible. If moving indoors is not an option, group all container plants in a protected area, like the inside corner of a covered patio, and cover them with plastic.

Mulch. Mulches can help plants growing in the ground. Use a loose, dry material such as pine straw or leaves. Mulches protect only what they cover, and they are best used to protect roots, crowns or may be used to completely cover low-growing plants to a depth of 4 inches. Leave complete cover on for no more than three or four days.

Cover. If they are not too large, individual plants can be protected by covering them with various sizes of cardboard or styrofoam boxes. Larger plants can be protected by creating a simple structure and covering it with sheets, quilts or plastic. The structure should hold the covering off the foliage to prevent branch breakage and to improve cold protection. The structure can be as simple as three stakes slightly taller than the plant driven into the ground. The cover should extend to the ground and be sealed with soil, stones or bricks. Do not just cover the foliage! Plastic covers should be vented or removed on sunny, warm days.

For trees that are too large to cover, you may at least want to wrap the trunk with an insulating material such as foam rubber or blankets. Even if the top dies, you may be able to regrow the tree from the surviving trunk.

Vegetables and fruit. Harvest any vegetables or citrus fruit that are ready. Even when freezing temperatures do not hurt the plant, cold can damage the heads, pods and flowers.

What to do after a freeze

• Water if plants are dry.
• Unless you are keeping them inside for the rest of the winter, move container plants back outdoors.
• Remove or vent plastic covers to prevent excessive heat buildup if the day is sunny.
• Pull back mulch used to cover low-growing plants.
• Prune away damaged growth on non-woody plants, and remove dead leaves. Delay hard pruning of woody plants until new growth begins in the spring, and you can more accurately determine which parts are alive and which are dead.
• Don't be too quick to dig up plants that appear completely dead. They may eventually resprout from the roots in April or May.