Find out how to overwinter rosemary and grow rosemary indoors to keep this wonderful herb growing all year!
A reader's question about overwintering rosemary reminded me that it was something I wanted to write about. I have had mixed results with rosemary plants over the years, but after killing a few I think I have finally gotten it right.
Every fall at least one person heading south for the winter will come to me with plants that they can't bear to let die. I am a sucker for a beautiful plant, so if I have room I usually say yes. I have gotten some awesome plants that way—jasmine, streptocarpella, orchids, geraniums, begonias, and rosemary.
How to Overwinter Rosemary
The rosemary I have now is several years old. Last year, it spent the winter on a cold windowsill at the library. The heat was on the fritz there last winter, but this plant sailed through the 50ºF nights with no problem. Occasionally, I would wrestle it into the sink and spray water over the needles, but it usually just got watered when we noticed the lanky new growth drooping. I brought it home and it spent the summer outdoors, enjoying the bright sunshine, heat, and rainfall. Now it is back inside for the winter.
The three most important things to consider when overwintering your rosemary are light, temperature, and water.
In the past, I have had success wintering rosemary in a south-facing window in an unheated upstairs bedroom. Now we are lucky enough to have a greenhouse attached to the house. We keep it fairly cold; the heat only comes on out there if it drops below 40ºF, and sometimes plants too near the glass freeze at night. And yet, the rosemary is thriving.
It can get a messy sprinkle of water on its needles weekly along with regular watering when the soil feels dry. Rosemary hates wet feet, so do not let yours sit in water. It needs well-drained soil, and a clay pot can help keep the roots from rotting. Many people make the mistake of letting their rosemary dry out too much, but a dry rosemary is a dead rosemary. Water when the soil feels dry.
That brings us to light. Rosemary needs the brightest light you have. I have had the best luck with south-facing windows, but many people resort to supplementing with grow lights. If you don't have access to a nice south-facing window, a western or eastern one will do. North-facing windows won't get enough sunlight, but if it's all you have, it's better than nothing!
If you are very lucky and your plant is very happy, it may even reward you with some blossoms!
Frequent clipping keeps it from getting too leggy, and when new growth starts this spring it will make for a bushier plant.
Growing Rosemary Indoors
The best part about keeping rosemary in the house is that you can stroke it every time you walk by and release that lovely fragrance into the air. Smelling it supposedly enhances cognitive function—clearly I'm not smelling enough of it! Rosemary can even reduce anxiety and stress and repel bugs.