We are fortunate to be able to garden nearly year-round in the Houston area, although we still get some freezes from time-to-time. But seldom do we get them in November. This week’s was not as bad as projected, but it was tougher in the northern and western suburbs than it was south of Interstate 10. Such a mild freeze may have damaged some unprotected tropical plants, but it probably didn’t kill much of anything.
If you do a good job of getting your tropical plants ready for our “winter,” they should easily survive future freezes and come roaring back in the spring. Examples of survivors are hibiscus and bougainvillea. You can lump a bunch of others into this category, too … like philodendron and crotons. I’m trying to protect a ton of coleus this year, and you can adjust the care tips below for any tropicals you might have in your landscape.
Here are the rules of thumb:
- Trim plants down to a manageable level prior to the first hard cold snap. They'll be easier to cover with sheets, blankets or frost covers.
- You only need to cover when the temperature is REALLY going to be at freezing (32 degrees F) or below.
- Cover them only with sheets, blankets or frost covers (also known as freeze covers or frost blankets). Do NOT cover with plastic or tarps alone. You can use tarps or plastic on top of the sheets, blankets, etc.
- Keep plants heavily mulched to insulate the root systems and preserve moisture.
- Water the root systems thoroughly before a serious cold snap.
- Remove the blankets the following day if the temperature rises above freezing.
- Pay no attention to “wind chill factors.” That’s only applicable to humans and pets. Only the actual temperature affects plants.
- If a part or limb didn't get covered and looks a little damaged, trim it off before it rots.
If you do happen to lose a plant due to freezing, you probably won't know about it for at least a month. Often, you can lose many limbs, but the core of the plant and its root system are very much alive. Just keep pruning the dead wood until as late as February. And if you wonder if it's worth the effort of trying to keep tropicals alive, remember they are relatively inexpensive to replace. Surprisingly, some people buy containerized tropicals in late summer or early fall (when they're often half-price), and baby them in a controlled environment through the winter. They don't have to get out there to cover and uncover stuff when cold spells come, and they have replacements on hand for any landscape plants that get ravaged during the winter.
For evergreens or anything in the ground to sustain any significant damage, we would need freezing-and-below temperatures for periods of time longer than the couple of hours we got Wednesday morning. In fact, things like azaleas and camellias absolutely LOVE this kind of weather.
I had a long talk the other day with a friend who once was a local TV weather forecaster (He's on the east coast now.) I just wanted to confirm a couple of things with him to help keep you from going into panic mode on plant protection.
First, he agreed with my observations that, for the season’s first two cold spells, local weather forecasters typically predict much lower temperatures than actually occur. From then on, though, they’re usually on the money.
My weather insider also concurred that radiant heat (coming from the ground) and any wind that’s blowing can combine to keep temperatures from getting as low as some forecaster predict.