As you are probably aware the severe cold has caused some damage to your landscaping. Some plants show the damage immediately; others may look undamaged for now but will not grow in the spring because the bark/cambium layer has been damaged. We have seen this problem in the past specifically with, but not limited to Viburnum, Ligustrum, and Azaleas.
The recommended clean up procedure is to let the dead foliage stay on the plants and trees until the last threat of frost or freeze has passed (i.e. early to mid-March). This dead foliage may help to protect (blanket) any viable plant tissue from the next cold spell. There is a very good chance we will get more cold weather before spring so as you look out your window and are disappointed by the condition of your property, be thankful for the protection it will bring should we experience another frost/freeze.
Some of the more sensitive plants (generally the ones with color) such as Hibiscus, Duranta, Arboricola, Downy Jasmine, Firebush, and Plumbago, etc. may be killed to the ground. You will not know what plants survived until spring, so avoid being too quick to dig up plants that look dead. Some of my Hibiscus I cut to the ground in 2009 did not sprout new growth until May. Last year, most of these plants did come back. However, this recent cold spell was much different then last year. In the twenty five years I‘ve lived in Tampa I cannot recall this many consecutive below freezing days. Plants that were already stressed from insect or disease will have a difficult time rebounding. Recently installed plants may also struggle, but your more mature plants will have a better chance of surviving the cold damage due to the ample supply of stored energy in their established root systems.
Be very careful not to over irrigate your landscaping during the recovery time. Use your finger to check the soil. If it is moist, do not run your irrigation. The over watering will only promote root rot and further weaken your plants. I have had my irrigation off since early November. Recent rain storms have been providing enough water for the landscape. Be cautious of relying on the rain sensor connected to your irrigation system to determine the watering needs of your landscape. Once a predetermined amount of rain is collected, the sensor will temporarily shut down the timer however, this sensor does not know the moisture level in the soil. The problem with rain sensors this time of year is they will dry out much faster than the soil thus permitting your automatic irrigation system to water even when it is not needed. Save water and your plants by shutting off your timer for the next few months and use your finger to monitor soil moisture. As the days get longer, the temperatures increase, and the landscape requires more water, you should then return to using your automatic irrigation system.
Your turf (St. Augustine, Bahia, Bermuda, Paspalum) that was exposed (not under trees) to the frost/freeze will turn brown.
The St. Augustine turf will be the first to green up.
On a more positive note, the severe cold may help reduce/control some insect pests this year…lets hope so!
Kenneth A. Roth
President / Horticulturist
Vivicon Inc.