Part 2: Cold Protection of Landscape Plants


What to Do Before a Freeze

Florida homeowners enjoy a vast array of plants and often desire a tropical appearance to their landscapes. Plants are often planted past their northern limit in Florida, although microclimates differ dramatically. Tropical and subtropical plants can be used effectively in the landscape, but they must be protected or replaced when necessary. Intermingle cold tender plants with hardy plants so that the whole landscape is not totally devastated by extremely cold weather. Homeowners can take steps to help acclimate plants to cold temperatures and to protect plants from temperature extremes. These steps range from selecting proper planting sites to altering cultural practices.

Planting Site Selection

Temperatures can fluctuate within a landscape due to microclimates created by tree canopy, proximity to structures, and other factors. Identify microclimates in your landscape when choosing the planting site for cold-sensitive plants. For example, tender plants should not be planted in low areas where cold air settles. Poorly drained areas result in weak, shallow roots that are susceptible to cold injury.

Shade

Tree canopy creates a microclimate that typically reduces cold injury caused by radiational freezes. Plants in shaded locations usually go dormant earlier in the fall and remain dormant later in the spring. Tree canopies trap radiant heat loss from the ground to the atmosphere, and thereby elevate air temperature beneath them. Shading from early morning sun may decrease bark splitting of some woody plants. Plants that thrive in light shade usually display less winter desiccation than plants in full sun. But plants requiring sunlight that are grown in shade will be unhealthy, sparsely foliated, and less tolerant of cold temperatures.

Windbreaks

Microclimates can also be created with fences, buildings, and temporary coverings. Adjacent plantings can protect plants from cold winds, while windbreaks are especially helpful in reducing the effects of short-lived advective freezes and their accompanying winds. Injury due to radiational freezes is influenced little by windbreaks. The height, density, and location of a windbreak will affect the degree of wind speed reduction at a given site.

Proper Plant Nutrition

Plants in good nutritional health will tolerate cold temperatures better and recover from injury faster than plants grown with suboptimal or imbalanced nutrition. However, late fall fertilization can result in growth flushes that are more vulneralbe to cold injury. Addtionally, fertilizers should be applied at the correct rates and times and only when needed. Because they have the potential to pollute water, some municipalities have adopted ordinances that regulate the formulations, sale, and application of lawn and/or landscape fertilizers. Check with your county’s UF/IFAS Extension office for recommendations and rules (see http://solutionsforyourlife.ufl.edu/map/).

Water Relations

Watering landscape plants before a freeze can help protect plants. A well-watered soil will absorb more solar radiation than dry soil, re-radiate heat during the night, and slightly elevate minimum night temperatures in plant canopies. However, prolonged saturated soil conditions damage the root systems of most plants.

Pruning and Pest Management

Avoid late summer or early fall pruning. This can result in growth flushes more prone to cold injury.

Healthy plants are more resistant to cold than plants weakened by disease, insect damage, or nematode damage. Routinely inspect for pests. Contact your county’s Extension Office for information on pest identification and recommended management (see http://solutionsforyourlife.ufl.edu/map/).

via ENH1/MG025: Cold Protection of Landscape Plants.

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