Rosemary adds a woodsy, energizing aroma and savory, herbaceous flavor to any dish. But this Mediterranean plant requires protection and special care to make it through the winter in very cold climates.

Gardeners in colder zones that regularly experience temperatures below 10ºF in winter must bring plants indoors or seek out cold-hardy cultivars. With a little maintenance and the right conditions, your rosemary plant will survive the winter to thrive next season. Here's how to care for rosemary in winter, whether in containers or in the ground.

How to Care for Rosemary in the Winter

Light

In-ground rosemary plants should be sited in a spot that gets at least 6 to 8 hours of full sun each day. Though days shorten in winter, the site you choose for your rosemary plant in summer should provide sufficient light in winter.

Watering

Plan to reduce or stop watering rosemary plants in winter. These plants require extremely well-drained soil, and overly wet or waterlogged soil can cause fatal root rot.

Fertilizing

Avoid fertilizing rosemary plants in fall or winter. These rugged plants rarely need any fertilizer at all, even during the growing season, except to address clear symptoms of nutrient issues like stunted growth and pale yellow leaves.

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Pruning

Avoid pruning or harvesting from outdoor plants during winter; the best time to prune rosemary is in the spring or summer after the plant has flowered.

Instead, plan to dry or freeze enough rosemary to use through the winter. Harvest no later than a few weeks before your region gets its first frost in the fall.

Mulching

Apply a few inches of an organic mulch like shredded leaves, straw, or salt hay around the base of the plant before your area's anticipated first frost. The additional root protection can help rosemary survive the winter's coldest temperatures in USDA zones 5 and 6.

How to Care for Rosemary in Pots Over Winter

Outdoor rosemary plants grown in pots can be moved to a sunny, south-facing spot against a wall. This positioning can help retain protective heat while providing sufficient light for the plant.

Indoors

You may also choose to overwinter rosemary plants indoors, either by bringing container plants inside or by digging up and transplanting rosemary in September. This will give your plant several weeks to acclimate to its new pot before you bring it indoors.

Watering

Be sure to use a very well-drained potting mix with plenty of perlite or coarse sand for drainage. If you do water indoor rosemary plants during winter, wait until the potting mix has completely dried out before watering again.

Temperature

Rosemary requires a combination of cool temperatures around 50-60ºF and several hours of bright sunlight each day, which can be difficult to achieve in many homes. A glassed-in porch or a basement, garage, or insulated shed with a very bright window may offer these conditions.

Lighting

For rosemary grown as a houseplant, choose your sunniest south-facing window and position the plant so that it received as much direct sunlight as possible. However, you may need to install a grow light to provide your plant with sufficient light.

Rosemary Winter Care Tips

• Site new rosemary plantings in front of a south-facing, light-colored wall for maximum sun exposure and protection from extreme cold.
• In USDA zones 6 and 7, look for cold-hardy rosemary varieties like Arp and Hill Hardy that have been bred to withstand temperatures as low as -10ºF.
• Protect in-ground plantings or outdoor containers from the coldest winter weather by using season extenders like cold frames, plastic sheeting over low hoops, or water-filled plastic cylinders.
• In very cold climates like USDA zones 4 and 5, a heated greenhouse may be required to properly overwinter rosemary outdoors.
• Another option for protecting outdoor rosemary plants in winter is to cover them with garden blankets, a floating row cover, or even an old sheet before nights when temperatures will drop into the 20ºF range. Uncover plants in the morning so they can soak up the sunlight.