You’ve seen those cute rosemary Christmas trees at your local florist, 1-800 Flowers, supermarkets and retail stores. They look like a perfect holiday hostess gift. And then you pick up a plant, inhale, and envision snipping off bits of the herb and baking fragrant rosemary focaccia.
But hold the shopping cart: Will that tree live long enough to make a single loaf of bread?
“I’ve had clients who kill them religiously,” says Elizabeth Hoffman, owner of West End Florist, an independent garden center in Evanston, Ill., who says that indoor rosemary plants tend to die at the end of March. “The plant is already stressed,” she says, noting low-light levels and dry indoor conditions, common in Midwest winters, make the plant susceptible to powdery mildew fungi.
Hoffman has come up with a few easy tips to keep rosemary trees alive:
Make certain that your rosemary has plenty of air circulation, which will help to reduce the chances of it becoming infected with powdery mildew, a major problem with indoor rosemary plants.
At the end of January, begin spraying your rosemary tree every two weeks with horticultural oil. Depending on your preference, you can make your own using kitchen oils such as grapeseed, safflower, soybean or canola oil (advised if you’re planning on cooking with your rosemary) or non-organic, such as petroleum-based oil. You can make your own by mixing 1 1/2 tablespoons of your oil of choice with 1 cup of water in a spray bottle. Adding 1 tablespoon of liquid non-toxic dish soap to that mix will help to emulsify the spray, making it easier to apply and to stick better.
She suggests taking the plant into the bathtub and completely coating it, making sure to wipe up any slippery surfaces afterward. “The oil coats the plant and suffocates the spores,” Hoffman says. Keep up the routine until middle of April, she advises, and the plant should be in clear.
Also, do not overwater. Rosemary likes to dry out between waterings. When in doubt, think of the country the plant is from, Hoffman says. Rosemary is native to countries like Greece, and grows on rocky mountain sides, where “the water visits and runneth away.”