Cynthia Meredith has been gardening with herbs, reading about herbs, and discussing herb gardening in Texas for more than 20 years. She has owned The Herb Cottage (www.theherbcottage.com) for over 10 years, selling herb plants to people all over our state.
Winter has set in a bit early this year, it seems. We've had snow in south Texas—although not at The Herb Cottage—sleet, a hard freeze, and generally cold and damp weather. While it did not snow here at The Herb Cottage, the temperature did dip to about 26 degrees for a few hours one morning and lots of landscape plants froze. I now have droopy passion vines on the fence, melted nasturtiums and frozen podrangea vine. Various hibiscus, Texas olive (Cordia boissieri) and henna (Lawsonia inermis), among other plants, are also frozen. Most succulents that were left out have frozen, too.
Frozen passion vines hanging on the fence.
Because so much in the landscape froze, the appearance of the yard area is very poor. The question now is "to prune or not to prune"? I know the prevailing wisdom is not to prune until later in the winter, when the cold weather is less likely to continue. The reason behind this is that during an extended warm spell this winter new growth will start where branches were pruned. And then another hard freeze would damage or kill the new growth, and may harm the plant.
Nasturtiums a couple of weeks ago.
Nastutiums today. Look at the little ones underneath that survived.
Actually it depends on the plant, whether it is considered a true perennial where the tops "always" die off or whether it is an evergreen, which normally keeps its foliage. My Texas star hibiscus (Hibiscus coccineus) is a true perennial. The branches always freeze back at first frost. I cut them back to about 4 inches above ground level, mulch the crown and by mid spring the plant is putting out new shoots. The same is usually true for the Mexican mint marigold (Tagates lucida). I am surprised that it didn't freeze yet, however, and still has fresh leaves on it.
The tender evergreens, which in my yard, include esperanza (Tecoma stans), vitex tree (Vitex agnus-castus) and henna, have all frozen. I will not prune the esperanza or the vitex at all because new foliage will appear on old wood. And it did not get cold enough to damage most of the wood on either plant. The dead wood at the tips of the branches, if there is any, will help insulate the plants from further damage during other freezes this winter. In the spring when new growth has started, I will be able to see where the freeze damage is and prune it off at that time.
Some references say henna should not have temperatures below 50 degrees, but I know mine has survived much colder temps than that—last year the leaves never froze. Another source says it can take down to 25 degrees. I have the plant rooted in a large pot because it's been in the same spot for so long. It became difficult to move into the greenhouse, so I've left it outside for about the past three or four years. Since it is frozen now, I may cut the roots that go into the ground and move it into the greenhouse to give it some TLC over the winter. The branches still show live wood when the thin bark is scratched, so the plant will definitely recover.
Frozen henna plant.
Of course, all the culinary herbs survived the cold just fine...except the lemon grass. It's pretty sad looking. The newly planted chamomile, salad burnet, lovage, cilantro, chervil, violets and thyme took the cold just fine. And the established rosemary, oregano, calendula and dill look great.
Now, all we need is some sun. It's been foggy and rainy for days, so some sun would really cheer us all up and make the plants perk up too. Newly seeded crops are growing slowly due to the recent lack of sun.
I hope your gardens are surviving the cold weather, and if you brought plants indoors, just remember to let the top inch or so of soil dry out in between watering to avoid an infestation of fungus gnats. Give your indoor herbs lots of sunshine or a fluorescent light.