To keep rosemary alive indoors in winter, give it the coolest, brightest spot in your home, around 50 to 60°F in very bright sun. Water carefully, never letting the pot go bone dry or stay soggy, and keep air moving around it. Most indoor rosemary dies from too little light, a warm, dry room, or a watering mistake.
Rosemary is a witch’s-kitchen staple and a notoriously dramatic houseguest. It thrives in a sunny garden all summer, then crisps up on the windowsill by January. The good news: its demands are specific, and once you know them, it’s very doable.
Why is my indoor rosemary dying?
Penn State Extension sums up the challenge: overwintering rosemary indoors may be difficult due to low-light conditions and too little or too much water. Illinois Extension adds that typical home conditions are a little too warm and too dry for it.
| What you see | Likely cause | Fix |
|---|---|---|
| Crispy, browning needles | Soil went completely dry | Water before it dries out fully; check it often |
| Pale, stretched, sparse growth | Not enough light | Brightest south-facing window, or a grow light |
| White powder on the leaves | Powdery mildew | More airflow; space it away from other plants |
| Sudden collapse, dark wet soil | Too much water, poor drainage | Clay pot with drainage; let the top of the soil dry first |
| Steady decline in a warm room | Too warm and dry | Move it somewhere cooler and brighter |
Where should indoor rosemary live?
Somewhere cool and very bright. Illinois Extension’s ideal overwintering spot has cool temperatures, around 50 to 60 degrees, and very bright sunlight. It suggests a sunny basement window or a partially heated back porch with lots of light. Penn State recommends a south-facing window in full sun, or supplemental lighting.
If your sunniest window sits above a radiator, it’s the wrong window. Our guide to reading the light by window direction can help you find the best spot you have.
Does rosemary need a grow light in winter?
Often, yes. Illinois Extension says most herbs need at least six hours of direct sunlight every day. If your window can’t give it that, the same guide says herbs can instead grow under fluorescent lights for 12 to 14 hours a day, 6 to 12 inches above the plants. Illinois also suggests a grow light as a way to keep rosemary going in a location cool enough for it.
How often should you water rosemary indoors?
Carefully, and by checking, not by the calendar. This is where rosemary is fussier than most herbs:
- Don’t let it dry out completely. Illinois Extension names rosemary as an herb that should never have its soil completely dry out.
- Don’t drown it either. Penn State warns against too much water, and suggests clay pots because they permit rapid drying.
- Check often. A cool room slows drying, and a sunny window speeds it up, so feel the soil every few days. The finger test in our houseplant watering guide is the one to use.
How do you prevent powdery mildew on rosemary?
Keep the air moving. Penn State notes rosemary is prone to powdery mildew and recommends adequate airflow between plants. Give it a little space from its neighbors on the sill, and don’t crowd it into a cluster of humidity-loving tropicals.
When should you bring rosemary inside?
Earlier than you’d think. Penn State describes rosemary as a tender perennial for USDA zones 8 to 10, so in colder areas it won’t survive winter outdoors. It recommends bringing potted plants indoors 2 to 3 weeks before the first frost date. If it’s still outside, check it for pests first; our checklist for when to bring houseplants inside covers the rinse, soak and quarantine.
Rosemary in the fall routine
Rosemary follows most of our six fall houseplant care changes, with one twist: it wants a cooler room than most houseplants. Keep it off the fertilizer until spring, keep it bright, and keep it away from heat vents.
FAQ
Can rosemary survive winter indoors?
Yes, with the right spot. Illinois Extension suggests cool temperatures around 50 to 60 degrees and very bright sunlight, or a grow light in a cool room.
Why is my rosemary turning brown indoors?
Usually because the soil went completely dry. Illinois Extension notes rosemary shouldn’t have its soil dry out completely. Too little light and a warm, dry room also play a part.
Is rosemary safe for cats and dogs?
Yes. The ASPCA lists rosemary (Rosmarinus officinalis) as non-toxic to cats and dogs.
What temperature does indoor rosemary like?
Cool. Illinois Extension suggests around 50 to 60 degrees in very bright light, which is cooler than most living rooms.