Rooted for Winter Growth
As winter approaches and the outdoor herb garden’s seasonal show winds down, many devoted dirt gardeners go into hibernation, to emerge in the spring eager once again to get their hands dirty. Winter is an essential period of rest for both plants and people.
Or not. Some of us don’t want the show to be over, no matter how bad the weather is. So we turn to pots. Containers are essential tools not just for the urban apartment-dweller growing parsley and basil on a kitchen windowsill, but for herb gardeners of any stripe, especially at this time of seasonal change.
A container herb garden is more than just a way to bring a piece of the outdoor perennial garden inside; it also can be insurance. Our most treasured plants — those that were given to us or have a special memory attached, unusual cultivars that are difficult to find or expensive to purchase, ones that are barely hardy enough for the climate, slow-growing plants we’ve had for a long time — will outlive the winter if we grow a piece of them in a container on a sunny porch or windowsill, or under lights in the basement or spare room.
The easiest way to do this is to root cuttings of the plants in question. Do it right now, while the plants still are growing vigorously and before they’ve been hit by the first frost. Once a plant’s growth slows in response to shorter days and cooler temperatures, stem cuttings will root less readily — sometimes not at all — so don’t delay.
Unlike seed propagation, a stem cutting guarantees that the offspring will be exactly like the parent plant. This is a necessity with cultivars that offer a particular fragrance or color variation but don’t breed true from seeds.
Few people have enough adequately lit space indoors to winter over every plant they have outside during summer. And some plants just aren’t worth the effort, even if you do have the space. So when you take your cuttings, discriminate.
Skip the annuals and short-lived tender perennials such as dill, cilantro, summer savory, marjoram and basil, as by now those plants are nearing the end of their life cycle and won’t make it through the winter anyway. They are easy to grow from seed if you do want them in the wintertime.
If the aim of your indoor winter garden is primarily culinary herbs for mealtimes, don’t bother rooting herbs that hold onto their flavor well when dried, such as thyme, oregano and sage. Many herbs lose much of their flavor on drying, or the flavor changes considerably, but these three are usable right from the pantry. They’re also tough plants in the garden and will survive almost any weather, so there’s no cause for worry when transferring them indoors.
Choose only healthy plants and pass over any that look stressed or show any sign of pests or disease. Life indoors is hard enough without starting off disadvantaged.
ROOT THOSE CUTTINGS
You can always just cut a few inches off the tip of a stem, stick in a glass of water on the windowsill, and in a couple of weeks you’ll have roots. Maybe. That’s how we did it as kids, and for easily propagated herbs such as mints, this technique still works just fine. Here’s another way to root a stem cutting.
First, have your small pots clean and rooting medium ready, whether you buy a bag of porous potting mix for seedlings or mix your own formula from peat moss, perlite, vermiculite, compost and other ingredients. Moisten the potting mix well, and fill the pots about three-quarters full of moist potting mix. Using a pencil or a chopstick, poke a hole in the center of the mix for the stem.
Using a clean, sterilized knife or pruning shears, cut off the top 3 to 5 inches of a non-flowering stem, making the cut at an angle to expose as much of the inner stem to the potting mix as possible. Strip off all the lower leaves to prevent their rotting in contact with wet potting mix and to encourage root development. If the leaves are large, clip back about half of the largest ones, thus reducing the surface area from which moisture is lost to the air.
Dip the cut end in rooting hormone, a powder available at garden centers that encourages speedier rooting, particularly in woody-stemmed plants. Take care with the rooting hormone, as it can irritate the skin, and don’t inhale the powder. Coat the cut end lightly, knocking off the excess.
Immediately stick the stem into the hole not quite to the bottom of the small pot. Firm up the potting mix around the stem to ensure good contact between stem and potting mix, adding more as you need it to fill the pot to within an inch or so of the top.
Keep the potting mix and the air surrounding the stem uniformly moist, either by misting it several times a day or by placing a kind of plastic tent over it (a plastic freezer zip-bag positioned loosely over the pot will do the trick) to hold moisture in.
Now wait and see if it works. Whether it takes a week or a month, you’ll know you succeeded when you see new growth at the tip, which means roots are forming below.
Need a suggestion for an herb to root from a stem cutting? How about pineapple sage (Salvia elegans)? It’s a good candidate because it’s a tender perennial and won’t survive the winter in many climates, and it roots readily. And while it becomes a huge plant outdoors in the right setting, its size is more manageable when contained in a pot. Its lovely light green leaves, brilliant red flowers and delicious pineapple scent chase away the winter blues.
Kathleen Halloran, former editor of The Herb Companion, is a freelance writer and editor now living in Las Vegas, where she grows herbs in containers.