As the days lengthen, gardeners take a look at their herbs and consider which ones might not survive winters chill. What to do? In some cases, a lot. In other cases, it’s time to make the final harvest and mark the spot with R.I.P. Here’s my take on overwintering herbs.
Gardeners who have lovingly tended their basil, cilantro, and chervil throughout the growing season are often reluctant to let them go when frost threatens. “Can’t I just bring them indoors until spring?” is the question I often hear. The answer is you can try, but it will be an exercise in futility.
These three herbs are monocarpic, meaning once they sense winter coming they shift into end-of-life activities – primarily flowering and setting seed for the next generation. They will keep on trying even if you attempt to trick them by bringing them indoors. It really isn’t worth the effort.
Many gardeners mistakenly think that scented geraniums (and their more colorful ornamental geraniums) are really annuals. Not so! All geraniums come from the tropics and will die back to the ground when a frost hits but if the ground remains unfrozen, there is still hope for the plant.
You can keep your scented geraniums alive in one of three ways. First, you can transplant them into a container and bring it indoors where it will be protected from freezes. Second, you can take cuttings, root them, and keep them under shelter until spring. Finally, you can accept that the plant will die to the ground after a hard frost but if you apply 3-4 inches of mulch to the base, the plant roots are likely to survive to re-sprout in spring.
This category is something of a mixed bag. What is a tender perennial for you may not be for other parts of Texas. One that is definitely tender in all of Texas is lemongrass. This herb from Southeast Asia has shallow roots and is easily affected by even mild frosts. Plants like this are best grown in a container, pruned back in late fall, and brought under shelter for the winter. Once spring comes and danger of frost is passed it can be brought back outside.
These are the herbs that laugh at cold weather and shrug off even snow and occasional ice. For the most part, nothing needs to be done for them except a layer of mulch to help retain moisture in the soil and reduce sharp temperature changes in the soil. Then in spring, a portion of the mulch will have disintegrated into fertilizer, giving your hardy perennials a boost toward new growth. What could be easier?