Shrubs Will Snap Back From Cold, Veggies Will Not
Hopefully, the cold weather is over. With any luck, our corn crops will revive from the cold and we will receive some more rain. The lack of rain may have actually benefited our farmers this year, as they would have planted many more soybeans, which would have had to be replanted. Be patient with the shrubs. Most will put out new growth and just be delayed. Unfortunately, the same cannot be said for the annuals and vegetables. However, we should be able to proceed with gardening now.
What should you do about those cold-damaged plants?
Damage reports have ranged from complete death of cold-tender vegetable transplants, herbs, and annuals to no damage at all on more cold tolerant species. How do you determine whether foliage, fruit, flower or stem has been lost to the cold? Obviously, a blackened, wilted appearance of foliage or flower indicates severe damage and the plant part will not recover. On herbaceous plants the foliage damage may appear as whitish areas on the leaves. It is not so evident for flower buds, fruit, or stems as the damage may be internal.
I know my blueberry, plum and rose flower buds are 90% lost to the cold. How? Because I took a pair of scissors and even though the fruit and flower buds of my roses didn’t appear badly damaged, when I cut cross-wise through the buds the entire center was brown. Likewise with the same blueberry and plum fruit.
Typically, flower buds are more cold tolerant than fruit because of the water content being higher in fruit. Obviously there are species differences and differences depending on location—plants in a more protected area will not show damage as much as a plant of the same species in a more exposed area.
For example, even though, all my rose flower buds were killed, the peony flower buds and the mock orange flower buds suffered no ill effects from the cold. Same with foliage. All of the new foliage on my crape myrtles and figs were killed, as was most of the new tip growth of the hollies, nandinas and other evergreens.
No cold damage at all on my columbines, Solomon’s seal, hellebores and hostas. So, before you start pruning of removing any plant parts, first, do a little detective work and determine the extent of cold injury. If the damage is not obvious take a knife or scissors and cut into a sampling of the flower buds or fruit.
To determine if there is any stem damage on plants with woody stems – trees, shrubs, and vines, – use a knife to peal back some of the bark on stems with frozen leaves. If you find moist, green sapwood just underneath the bark, that stem is still alive. Live stems, even leafless ones, will regenerate leaves when the temperatures warm consistently.
Only cut-off stems that have been killed by the cold. These will have sapwood that is dry and brown when you peal back the bark. Cut dead stems all the way back to live wood. The amount you cut will vary greatly depending on the plant. For instance, the stem tissue on the tips of my crape myrtles was so severely damaged that the bark literally froze and busted away from the stems. I will wait a few weeks to see exactly how much I will need to prune.
If you are unsure about where to cut, wait until new growth emerges. This will tell you exactly where the dead parts met the living. Simply remove everything back to where the new growth is sprouting out.
Flowers and other herbaceous plants injured by the cold need attention without delay. Most of the damage will be to the uppermost leaves of hollyhocks, daylilies, bee balms and other plants. Cut them off cleanly with a sharp scissors or hand pruners. Old, faded and frozen flowers should also be removed. Some will generate more flowers and others will not, depending on the species. Apply a liquid fertilizer to all injured plants to speed their recovery.
Make sure all freeze-damaged plants have adequate moisture. Injured leaves and stems will loose more moisture through their wounds than undamaged ones. Keep the soil moist, but not overly wet.
Now, cross your fingers and hope we are finally past the cold weather!