Dallas Morning News - March 4, 2021
Responding to Freeze Damage
Most common questions lately? How to treat the freeze damaged plants and what to do with the massive amount leaves on the ground.
As a general response, the plant damage appears (so far) to be mostly cosmetic on the woody plants including trees, shrubs and vines. Most adapted perennials (wood ferns, salvias, coral bells, hardy herbs, etc.) are dead on top, should be cut back to the ground and will re-emerge in the spring. Some are already emerging. Poorly adapted perennials, annuals and any plants that turned to mush need to go to their new home in the compost pile.
Some pittosporum and other burned shrubs may completely re-leaf or start new growth nearer the bases of the plants
Damage to woody plants can go a couple of ways. Badly burned plants like pittosporum, nandina, loropetalum and both Japanese and wax ligustrum can be stripped of dead leaves or tip pruned in order to look better. After the buds break in the spring, prune plants to just above the point of new growth. Another approach is to sit back and wait until the new growth breaks and then prune the dead off beyond that point. This means having to look at brown leaves a little longer. Split trunks are a more serious sign but can be treated with Tree Trunk Goop and splints on each side of the split cinched tightly with ratchet straps or other devices.
Freeze burned live oaks should be fine
Bigger plants like live oaks, Mexican white oaks (aka Monterrey oak), Canby oaks and other evergreen to semi-evergreen trees that are still holding brown leaves should be left alone. They are already kicking off many of those dead leaves and that is actually a good sign. Evergreens holding on to their brown leaves tightly might indicate more serious damage.
Mexican white oaks and other adapted evergreens look bad but will probably re-leaf and be fine
Brown leaves on palms can be pruned away – they won't green back up. Some landscape folks are recommending treating growing tips with copper or sulfur products for disease issues that might pop up. Rather than using single element products like those, I prefer hydrogen peroxide mixed 50/50 with water or replace the water with the entire Garrett Juice mixture. If currently using an organic management program, probably neither is needed. Healthy soil and increased levels of sugars in the plant sap helps prevent freeze damage and disease problems.
If your palm trees are Needle, Sabal, Windmill, Mediterranean or Pindo, they will probably continue living unscathed or re-leaf and survive – especially those first three. If your palms are Washington, Date, Queen, Areca or Sego (not really a palm), they may be goners unless they were strongly protected.
Mulch the leaves and use to cover bare soil in beds and gardens (supervision by Nellie (l) and Tater).
Management of the fallen leaves is what I always recommend adjusted for the volume. Most important - do not put the leaves in bags and send to the landfills! You are a very bad person if you do that. Leaves can left where they have fallen in some cases if not covering small plants – that's what happens in the forest, but a better plan is to mulch them (with the mower) into a much smaller volume and use to cover bare soil in the landscape and vegetable garden. Excess can go in the compost pile to break down into Nature's finest fertilizer. Good luck.