Dealing With Frost Damaged Yards
by Paul Noe
Faced with a yard full of frost damaged plants, often the first impulse of the gardener or homeowner is to start pruning, removing, and replacing their plants. Unfortunately, this is usually not the best course of action.
Any plant that is still alive will attempt to recover from freeze damage. Many plants that look completely dead will begin to recover when the weather warms up. Some plants will have lost all their woody parts, but will begin to re-grow from root or stem tissue. This is a normal and typical recovery process for the plant. The extent of damage may not be apparent until re-growth starts in warm weather. In some cases, root systems or circulatory damage is not yet apparent. Some of the plants so damaged may show no outward signs until heat or other stress causes the plant to collapse. What this means to you is that pruning or removing should be delayed in all cases where frost damage is apparent. When growth resumes in the spring, you will easily see which stems or branches are not recovering fully. By the beginning of March, many plants, like Mock Orange, Photinia, Privet and Texas Sage will leaf out and show generally good recovery. Species like Oleander and African Sumac probably won’t show any signs of re-growth until April or May. Replacement and/or pruning decisions might need to be delayed until May, unless the decision to replace these plants with other species has already been made.
Palms and other monocot plants such as yuccas and some grasses are particularly prone to damage through pruning. The palms are particularly vulnerable because they have only one growing point, called the heart-bud. If this heart-bud is damaged, palms are incapable of manufacturing a new one. Any additional stress on the heart-bud, or the removal of the insulating thatch (dead leaves) could cause the palm to die. Generally, no pruning should be done on any palms until at least five strong new leaves are visible.
Olives damaged by a freeze can be pruned beginning in March. Pruning should consist mainly of removing twiggy secondary growth, while allowing scaffold branches to remain. Olives pruned in this manner should show a generally strong recovery by mid-summer.
Plants damaged by freezing should not be fertilized until active growth resumes in the spring. The loss of growing tissue and leaves experienced by most freeze or frost damaged plants inhibits their ability to metabolize and use fertilizers. In some cases, more damage could result from improper and over-zealous fertilization. This is again critical for palms, which should not be fertilized until hot weather in June or July, and again in August or early September.
When fertilizing does take place, caution should be used, taking into account the compromised state of many plants. Probably the most effective fertilizers will be those which are balanced and which have a low analysis, such as 5-10-5 to 9-9-9. To help soil microorganisms re-establish, homemade compost or commercially available mulches will be helpful. In no case should strong dosages of high nitrogen be used on landscape plants following a severe freeze. Even plants with no apparent damage can be disturbed by rapid growth caused by excessive nitrogen.
Proper watering of damaged plants is vital. While moist soil is necessary in almost all cases to avoid further damage from drying winds, plants which have had foliar damage or root damage have a compromised ability to make use of excess soil moisture. This means that the watering regime must be carefully watched, and the soil watered only when it begins to dry significantly. Doing otherwise may result in root rot and further losses. The reduced soil evaporation rate in cool weather combined with reduced demand from damaged plants indicates watering no more than once a week. Over watering at this time would be devastating to plants that have been significantly damaged by a severe freeze.
Conservatism is called for in all gardening and landscaping activities. Too much water, fertilizer, or pruning could be detrimental and could cause much more loss than might be experienced otherwise. Remember, replacing in haste will waste plants and money.