A Message from Joe Williams, the Houston Zoo’s Horticulture Manager
I’ve had a number of guests and staff asking me about their plants both here and at home after the cold weather of late and what to do with freeze damage. The best thing to do with almost everything at this moment is to leave it alone.
- Don’t trim any woody stemmed plant or perennial until we are certain to not freeze again. The dead and/or unhappy plant matter will help to insulate the rest of the plant if we do freeze again. More importantly, if you cut back to green wood you could promote new growth. This is a huge expense of energy for a plant that is already hurting. Also the new growth is the most sensitive to the cold. The culmination of the energy output and continued damage almost certainly ensures this plant will die.
- Plants such as bananas, gingers, cannas and elephant ears can be trimmed back to the ground and mulched. For these you can trim to just below the damaged portion and they should be content. If there is still green, happy tissue the roots will still be getting energy from the stem which will promote a stronger plant next year. For the most part we are trimming the gingers and bananas just below the damage because we tend to use them as structural components of the gardens and they’ll be walked upon if we are to trim them to the ground. This won’t be a good year to get fruit from our bananas or flowers from our gingers, but the plants will come back. The majority of plants listed above are at least root hardy to anywhere from 10 to 15 degrees Fahrenheit.
- When considering tropical trees, if they are kicking off old leaves, this tends to be a good thing. This means that the tree is still trying to live, normally some sign of bud growth or the trees attempt to eliminate the energy necessary to maintain the leaves and concentrate of root growth. When a tree hold on to dead leaves if tends to be a bad sign. A quick means of checking the potential viability of you trees that do have dead leaves is to attempt to strip a leaf, it should come of fairly easily. This is also works to see if a newly transplant tree is doing alright.
- Now on to palm trees… Most palms that are sold here are supposed to be hardy to at least 20 degrees. This doesn’t mean that nurseries haven’t brought in other more tender palms or that we don’t have a handful of really tropical palms here. Don’t cut any of the ugly dead fronds off until we are certain not to freeze. The most important thing is keep the heart of the palm warm and insulated. This is the area where the leaves emerge from the trunk. The dead leaves give the palm a couple more degrees of cold tolerance. We’ll also wrap or provide heat to palms that we know are sensitive tot the cold. I can provide a list of the palms that are sensitive for any future freezes.
We aren’t going to know for certain the extent of the damage until spring. The good thing about being in Houston is that spring tends to begin in February. As I said before the best thing to do with most plants is just leave them alone. I know it’s tough to look at ugly plants, but for most plants either winter defoliation or being knocked back by freeze is the norm and they’ll come back as strong as ever.
