The two things rosemary plants (Rosmarinus officinalis) dislike many are deep cold and moist soil. In the warm-winter climates of U.S. Department of Agriculture plant hardiness zones 8 through 10, in which rosemary is a perennial, deep cold usually is not a problem. Winter rains, however, could have you thinking about how to move your in-ground rosemary indoors to maintain its feet dry until spring. The key to successful indoor overwintering is to supply your rosemary with indoor conditions as close as soon as it exterior ones.
Potting Your Rosemary
Lift your rosemary from the soil no later than Labor Day, advises horticulturist Barbara Pleasant. Give it a blank clay container with drainage holes; water evaporates rapidly through the porous clay, so the potting medium will not become soggy. Insert a 1 1/2- to 2- inch layer of perlite or fine gravel to the base of the pot. Use a loose, rapidly draining commercial soil mix, or make your own of 2 parts loam, 2 parts sand and one part peat moss.
The Adjusment Period
After watering the potted rosemary well and letting it drain, prune it back from one-half. This lets it channel energy into root growth instead of the blossoms it normally creates beginning in late autumn. Then move it to an outdoor spot with two to four hours of daily sun. Keep it there till you bring it it indoors in mid-October. After a summer in the soil, this adjustment period prepares the rosemary for your home’s lower light conditions. During this time, water only when the potting medium’s surface feels dry.
Ditching The Trespassers
Aphids, whiteflies and spittlebugs all infest outdoor rosemary. Even when pruning gets rid of the pests, the adjustment period is long enough for them to make a recovery. Aphids and whiteflies drench their feeding sites with gooey, clear waste, and spittlebugs cover themselves with foam. Before moving your plant indoors, hit it with a strong precautionary spray of hose water to dislodge any residual insects.
Light, Temperature And Water
The excellent indoor website for your rosemary is near a south-facing window getting six or more hours of daily sun. Do not let the plant touch the cold glass. Otherwise, place it 3 inches below fluorescent lighting for 14 hours a day. It enjoys winter temperatures in the 50- to 60-degree Fahrenheit range, but decent light is more important than fever. Water when a 6-inch wooden skewer inserted as far as it will go in the medium picks up only several particles. To avoid injuring the roots, use room-temperature water.
When Green Rosemary Turns White
White or grayish mould on your rosemary is powdery mildew resulting from poor air circulation. Prune the branches that are affected, disinfecting your tools in a solution of 1 part household bleach to 9 parts water between cuts and once you’re finished. To avoid future outbreaks, spray the plant weekly with a mix of 1 part nonfat milk to 9 parts water and also put a tiny electric fan nearby to keep the air moving.