From Better Home and Gardens
By Lauren Landers
Rosemary is a Mediterranean herb that can manage light frosts but often struggles to survive extreme cold. Fortunately, you can protect rosemary from winter’s chill by overwintering it indoors or providing outdoor protection in milder climates. Discover essential tips for keeping your rosemary thriving through the cold months.
How to Protect Rosemary Outdoors in Winter
Rosemary plants can survive winters outdoors in USDA Zones 8-11, where the temperatures typically remain above freezing. However, even in these areas, give your rosemary a bit of protection to support its survival through the winter months.
Add Mulch
Rosemary plants thrive best in sunny spots and protected from strong winds. To assist with their winter survival, apply a 3- to 6-inch layer of natural mulch like wood chips or weed-free straw around the base before frost. This mulch acts as an insulator, shielding the roots and preventing the soil from freezing.
Add Cones or Row Covers
In addition to mulching, it’s beneficial to shield the stems and leaves of rosemary plants before winter arrives. Rose cones or floating row covers are good materials for protection. When using row covers, choose those specifically designed for frost protection, and secure them at the soil line with rocks or landscape staples.
Prune and Mulch
Pruning and mulching are other methods for protecting rosemary. After the first light frost of autumn, trim small rosemary plants down to about 6 inches above the ground, taking care not to cut into the woody stems. Then, pile 4–6 inches of chopped autumn leaves, straw, or another natural mulch over the plant to insulate it during the winter.
Potted rosemary plants may also survive outdoors with mulching, but you’ll want to wrap frost-sensitive pots and containers with burlap, bubble wrap, or old blankets to keep them from breaking.
How to Overwinter Rosemary Indoors
Rosemary struggles to withstand the cold winters typical of Zone 7 and colder regions. To keep your rosemary thriving in these areas, plan to bring your plants or cuttings indoors during winter. This indoor transition keeps them out of freezing temperatures so they make it to the next growing season.
Overwinter Entire Plants
To overwinter whole rosemary plants, dig up the plants in autumn before the first frost. The plants grow better if they have a large root ball attached, so place your shovel at least 6 inches away from the rosemary plant stems before you begin to dig. After you’ve dug up the plant, place it in a large pot with fresh potting mix and allow it to acclimate to its growing container for a few days before moving it indoors.
Take Stem Cuttings
If you don’t want to dig up your entire rosemary plant, you can also take cuttings of plant stems and root them in water or soil with a bit of rooting hormone. Rosemary cuttings should be about 4 to 6 inches in length. Cuttings taken from healthy branches with new growth tend to root best. Rosemary cuttings can take four to eight weeks to develop roots, so be patient as you wait for the new rosemary plants to grow.
Indoor Care Tips
Caring for rosemary indoors during winter is straightforward. Place your rosemary in a window that gets six to eight hours of bright indirect lighteach day. Water only when the soil is dry to the touch. To keep the leaves supple, consider using a humidifier or placing the plant on a pebble tray to increase humidity.
Hardening Off
When spring arrives, and the threat of frost is gone, acclimate your rosemary plants to the outdoors a little at a time. Start by placing them outside during the day and bringing them back in at night for several days. Once they’ve adjusted, move potted rosemary permanently outside for summer, or replant them in your herb garden.
