During this season of short, dark days, indoor herb gardens offer welcome greenery and fragrance, as well as adding zest to cold-weather stews and soups.
“In the winter, even indoor plants won’t be doing much, but an already established herb plant can thrive quite happily in a sunny window,” said Sonia Uyterhoeven, who teaches herb gardening at the New York Botanical Garden.
“Easy herbs to grow inside are basil, chives, parsley, oregano, sage, thyme, mint, cilantro and bay,” she said. “If you bring lemon verbena inside for the winter, it will drop its leaves. But just cut it back hard and in a month it will look good again. It’s fragrant and really lovely. Rosemary can do OK, but needs time to adjust to lower indoor light and should be given two weeks to transition first.”
For rooms with limited light, parsley, chives and mint are quite forgiving, she said. Basil, oregano, rosemary and sage, all Mediterranean plants, generally do better with much more sun. Most herbs are happiest with 6 to 8 hours of sunlight a day.
“The biggest mistake people make is underestimating how much light herb plants need,” explained Leda Meredith, who teaches about herbs and herb gardening at the Brooklyn Botanic Garden.
“Your basil plant is not going to love you for just two hours of sunlight in the morning. You have to remember that to a plant, light is food.”
If light is a challenge, fluorescent light is full-spectrum, works well on plants and is much cheaper than plant lights, she said.
Ginger root is another wonderful, easy and often-overlooked option for indoor gardens, said Meredith.
“Ginger is a great idea, and the long glossy plant leaves are very attractive. Florists use it a lot in arrangements. Just get a ginger root from the grocery store, chop it into 1-inch chunks, and plant those in a pretty good-size pot with just an inch of potting mix on top, leaving several inches between each piece of ginger. That’s it,” she said.
“Start watering them and, after a couple months, you'll realize that the whole top of the pot is ginger root. They form horizontally, not vertically, and you can harvest what you want,” she said.
Ginger plants do well with anything from full sun to bright indirect light most of the day, but are pretty tolerant, she said.
General rules to help kitchen gardens thrive in winter include making sure pots are sufficiently large; herbs almost always need to be repotted in containers two to three times the size they came in.
“The more space they have to grow, the better they'll do,” Uyterhoeven said.
“Around 70 degrees is ideal for most herb plants, and placing a bowl of water beside them will give them a little extra humidity,” Uyterhoeven said.
She and Meredith warned against overwatering and over-fertilizing indoor herb plants, which should generally not be watered until the soil just below the surface is dry. They tend to lose their scent and taste if given too much fertilizer.
Plants should be rotated periodically to ensure all sides are exposed to sunlight, and they do best when planted in a combination of potting soil mix and compost.
They also “love a good haircut,” according to Uyterhoeven, and can be cut back by a third to a half periodically.