By Paris Wolfe, Blogmaster, The Herb Society of America
Last spring, Mitch Allen cheated.
The Cleveland-area publisher bought a 20-inch tall rosemary bush. Its established size confirmed a multi-year head start in a nursery. And created a highlight in his herb collection.
If you’re from Northeast Ohio, you know it’s nearly impossible to start small and build big with this Mediterranean native. Like many a gardener, rosemary has an aversion to cold, dark, snowy winters. Did I say “dark?”
And so, ambitious herb gardeners are forced to cheat. A little. Like Mitch, they bring the woody perennial inside for winter.
“It’s still alive, but about half the stalks are turning grey,” he says of his specimen. “The other half looks pretty good.”
Mitch has plenty of company.
“Overwintering rosemary is one of our most asked questions, especially here in Cleveland,” says Karen Kennedy, HSA education coordinator.
She advises growers to provide a sunny location and keep the soil moist but not wet.
The biggest challenge is lack of sun. That can lead to leggy growth. I recommend pruning that when the plant is transitioned outside in the spring. Of course, you can continue to cook with the herb even if it is leggy.
Another challenge in cold climates can be forced-air heating. Plants dry out quickly in warm environs with low humidity, particularly plants that are pot-bound from the growing season. The solution: Water judiciously and mist often.
The final significant challenge is insects. To prevent them inspect often and rinse foliage under running water periodically to dislodge eggs and populations of spider mites and white flies. Mealybugs are best removed with cotton swabs dipped in rubbing alcohol.
During the winter, Mitch plans to keep his plant alive and buy his culinary rosemary at the market.