COLORADO – The late May snow storm and freeze is going to be felt for a while. Breaking tree limbs and gardeners’ hearts, that wallop froze buds, fruit, vegetables, and flowers that had all of us eager for summer. Many people are trying to put their split trees back together again.
Freeze damages new growth on plants in different ways. In some cases, the entire leaf and stem might be left blackened and dead; in other cases just the edges of the leaves are killed. If you notice odd leaves, strange spots, or deformed flowers it could due to freeze.
Harder to spot are the plants that are killed. Yes, a shriveled blackened tomato plant is probably a goner, but perennials can look like that yet still have energy to send out new growth. Give them a couple of weeks before remembering them with bagpipes, songs, and toasts, because they might just bounce back. Once they do, prune off frost-killed tissue.
Trees that had their leaves frozen not once, but twice in the past couple of storms need to be watched and coddled this summer. Often trees have stored energy to push new leaves should they lose their first set. But after losing two sets of leaves trees can use up energy that could compromise them should anything else defoliate them. If our summer dries out, water them and keep pests from munching a lot of their leaves. Hold off on fertilizing; that encourages top growth but roots need time to recover.
As you continue the cleanup, please note that we don’t recommend that split or broken trunks and branches be glued, duct taped, screwed, cabled, stapled, super-glued, tied, propped, cemented or banded back onto the tree. This can lead to a very hazardous situation.
Pruning off the torn branches and cleaning up wound sites is the best answer for damaged trees. If the trunk bark is torn, take a sharp knife and clean the torn bark from the tree, leaving a smooth edge to the wound. We don’t recommend any wound paint – the tree will seal that area itself, and wound paint would only lock disease organisms or water into the wound.
If people are doing their own tree cleanup, we always emphasize safety and encourage people to be cautious on ladders or when climbing a tree. Look before you climb to see if any hazards, such as power lines, are in the way.
If possible, trim branches to leave a clean cut, making sure you follow the three steps for proper pruning (which prevent bark tears):
1. Twelve inches away from trunk or from where you want the prune to be, make your first cut on the underside of the branch, sawing upwards through one-third of the branch.
2. One-inch outward from the undercut, saw downwards through branch. At the point of no return, the weight of the branch will snap the limb, but the undercut will stop bark tearing of the tree.
3. Make your last cut just outside the branch collar, the spot where branch and trunk join. Often, you can see a slight swelling at this point.
Find a diagram of this pruning method at PlantTalk Colorado, planttalk.colostate.edu.
If you’re not sure if your tree is a goner, contact an arborist to assess it. Those with less damage should be cleaned up, then have close attention to care over the winter. Water them if we’re dry, and keep them healthy.
By Carol O’Meara, Colorado State University Extension. Colorado State University Extension, together with Boulder County Parks and Open Space, provides unbiased, research-based information about consumer and family issues, horticulture, natural resources, agriculture and 4-H youth development. For more information contact Extension at the Boulder County Fairgrounds, 9595 Nelson Rd., Box B, Longmont, 303.678.6238, e-mail firstname.lastname@example.org or visit ext.colostate.edu/boulder.