News Release Distributed 12//17/10

By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings

Winter is here, and many questions always arise this time of year about protecting landscape plants during the cold months of December, January and February.

One sound piece of advice is to pay attention to the weather forecasts and try to know a couple days ahead of time when freezing weather is approaching. Keep in mind that frosts and freezes are different. The weather conditions prior to a freeze or frost also play a role in the effect of these temperatures on plants.

Thoroughly water landscape plants before a freeze if the soil is dry. This is especially important for container-grown plants. Shrubs in landscape beds also can be helped with irrigation prior to a freeze. It would be best, however, to make sure your shrubs received adequate irrigation and/or rainfall during the fall. Strong, dry winds that frequently accompany cold fronts may cause damage by drying plants out, and watering helps prevent this. Wetting plant foliage before a freeze does not, however, provide any cold protection.

Move all tender plants 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. Keep in mind that your cool-season bedding plants are adapted to the cold temperatures that are normal in Louisiana during winter, so cold protection typically is not needed for them.

For plants growing in the ground, mulch them with a loose, dry material such as pine straw or leaves. Mulches will only protect what they cover and are best used to protect below-ground parts and crowns. Mulch also may be used to completely cover low-growing plants to a depth of 4 to 6 inches – but don’t leave them completely covered for more than three or four days. Many folks heavily mulch their tropical hibiscus in landscape beds using this method. Smaller, individual plants can be protected by covering them with various sizes of cardboard or plastic foam boxes.

Larger plants can be protected by creating a simple structure and covering it with sheets, quilts or plastic. The structure holds the covering off the foliage, preventing broken branches and improving cold protection. It need be nothing more elaborate than driving into the ground three stakes slightly taller than the plant. The cover should extend to the ground and be sealed with soil, stones or bricks. Plastic covers should be vented or removed on sunny, warm days.

For severe freezes when temperatures dip into the teens, providing a heat source under the covering helps. A safe, easy way to do this is to generously wrap or drape the plant with small outdoor Christmas lights. The lights provide heat but do not get hot enough to burn the plant or cover. Please be careful and use only outdoor extension cords and sockets. If necessary, you may prune back a large plant to make its size more practical to cover.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.lsuagcenter.com/lahouse and www.lsuagcenter.com/lyn.

Rick Bogren