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Monday, Oct 23, 2017
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Extension agents involved in coverup

Last winter, many people asked: What is the Hillsborough County Extension Service trying to cover up? The answer is simple. We try to protect plants in the Bette S. Walker Discovery Garden that we think we can't live without! We're certain you will see our "coverup" again this year! Plant coverings are frost protection versus cold protection. Covers can be sheets, quilts, or frost/freeze cloth and should be in place before the sun goes down. Other than frost/freeze cloth, the covers must be removed during daylight. Frost/freeze cloth may remain in place for several days as air and light flow through the cloth. Plastic is not a good choice because it transfers the cold onto the plant. You can, however, put plastic on top of the sheet or quilt during windy freezes or on very cold nights. The covering you select must extend to the ground to capture heat from the soil and provide wind protection. You can make a frame over the plant you are covering, then place the covering on top of the frame. This way, nothing touches the plant itself. A cardboard box large enough to fully cover the plant is another option.
Even though you have covered your plants, an additional source of heat may be needed. Christmas tree lights — not LED because they do not provide heat — or a light bulb may provide enough heat to protect your plant from freezing. Covering tropical plants in your landscape and those not hardy in your zone may help those plants survive cold weather. If you can't live without tropical plants and they have not survived the past few winters, you may need to plant them in containers so you can move them from your landscape to your porch, lanai or garage. Your garage may be 10-plus degrees warmer than the outside temperature, which is another option for plant storage during freezing temperatures. Container plants can be covered to the ground or grouped together and covered. Don't encourage new plant growth by pruning or fertilizing, because the plant will be more prone to cold damage. Pruning alters the hormone balance, resulting in a growth flush. There are two options on pruning. The first is to delay pruning post-freeze until you see new growth and after the risk of a future freeze passes. Then prune beyond the point of black or brown stem coloration. The damaged plant material insulates and protects the live parts of the plant. The second option is to prune all dead plant material and freeze damage after the freeze. This makes it easier to cover and protect the plant if another freeze occurs before spring. Healthy plants are less prone to cold damage and more resistant to insect damage or disease. Landscape plants need less fertilization in the fall because their nutrient intake is smaller that time of year. Slightly moisten the soil before a freeze or near-freeze because moist soil releases more heat than dry soil. Hand watering the ground beneath the plant helps. This is a great time of year to mulch, now that it has cooled off. Maintain a 3-inch layer of mulch after it settles. Mulch helps regulate the soil temperature and protects the plant roots. After a freeze you should check to determine whether your plant needs water. The leaves could be losing water while frozen water remains in the soil. Applying water to the soil will provide a thaw and water your plant at the same time. Practice the first principle of Florida-Friendly Landscaping, which is Right Plant, Right Place. Consider sun/shade, wet/dry, mature size, soil type and pH. Cold sensitive ornamentals should be planted in an area where air flows freely. Use screening, fences, and landscape design where multiple plants are located strategically for protection. Well-drained soil enhances root growth and stability. Plants in the shade become dormant earlier in the fall and stay that way until later in the spring. You can reduce the cold injury the plant will suffer if you plant it under a tree canopy, because the evening temperature is higher. Shade-thriving plants have less moisture loss than full sun-loving plants. Sun-loving plants living in shady conditions are less cold tolerant. Most perennials are root hardy. Although the foliage will die back to the ground, new growth will appear in the spring. Be patient, because it can take several months before shoots are visible above the ground.

Lynn Barber is the Florida Yards and Neighborhoods agent at Hillsborough Extension. Reach her at BarberL@hillsboroughcounty.org.
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