Rosemary- Overwintering Indoors
Master Gardener Barb P. shared photos she took of the flowering rosemary plant in her sunroom.
In our area it is difficult to overwinter rosemary outdoors so I treat it as a container plant which makes it infinitely easier to bring indoors. But bringing it indoors requires different care than when it is outside.
OUTDOORS TO INDOORS
If you have rosemary planted out, you may pot it up using appropriate potting soil (not garden soil) and pot size with a drainage hole and tray. Follow recommendations about preparing your plants to bring them inside.
If possible, acclimate the plant to the indoors by bringing it inside a few weeks before the first expected frost date, October 15 here in S. Central PA. If you can open the windows and keep the indoor temperatures low, it will make the transition easier than suddenly bringing it into a warm house.
All I want is for my rosemary to make it through the winter and not die, so I can move it back outside when spring comes.
Fertilizer and Pruning: I don't encourage my rosemary to grow during the winter so I don't fertilizer or prune, except for a snip here and there. Rosemary will go dormant during the winter.
Light: My plant is in the basement in front of a south facing set of doors and gets about 6 hours of light each day. Rosemary needs 6-8 hours of light as it did outside so you may need to use artificial light to supplement it. A fluorescent light or grow light can help. Rotate the plant every week or so to keep the plant growing evenly on all sides.
Temperature: As a native Mediterranean, mild-region plant, rosemary will expect cool winters (not freezing) temperatures. An area that is consistently 55 to 60°F is good. Our basement is only heated when we use it for projects so it is usually around 60-65°.
Watering: As with most plants brought in to overwinter, consistent watering is one of the important keys to keeping it alive. Water when the surface is dry, usually once every 2 weeks until the soil is wet and water comes through the drainage hole. We have a dehumidifier in our basement so I mist it on the alternate weeks when I don't water it.
About an hour after watering I check the saucer under the plant and empty any water from so the roots aren't sitting in water. I let the tap water I use sit in an open container overnight to allow the chlorine to dissipate.
Air Circulation: Good air circulation can alleviate some problems with mildew and mold. If you have several plants overwintering indoors, make sure there is good spacing between them.
Interesting Information About Rosemary
The name rosemary derives from the Latin for dew-"ros"- and sea -"marinus;" thus, dew of the sea. A legend says that the Virgin Mary spread her blue cloak over a white-blossomed rosemary bush when she was resting causing the flowers to turn blue. The shrub then became know as the "Rose of Mary."