Growing Rosemary for Years: Drainage, Winter Cold and Cuttings
Overwatering is the usual way rosemary is lost. How to pot, water and overwinter it, how much cold it takes, and how to root cuttings for the next plant.
Rosemary comes from dry, rocky ground around the Mediterranean, and it still behaves that way in a garden. Give it sun and fast drainage and one evergreen plant can keep a kitchen in sprigs all year.
When a rosemary plant dies, water is the usual suspect. NC State Extension says it has “a low tolerance for wet, humid environments” and that overwatering is “the common cause of plant decline or death.” Cold matters too, and how much it can take depends on the plant and on how wet the roots are when the frost arrives.
What does rosemary need to thrive?
Full sun and soil that drains freely. NC State lists light, slightly acidic, dry to medium soils and six or more hours of direct sun, and notes it tolerates drought, salt and most soils except clay.
In the ground, the Royal Horticultural Society says established plants shouldn’t need extra watering or feeding, even in poor soil. On heavy clay, a raised bed or a pot drains better.
For a pot, the RHS suggests one at least 30 cm wide and deep, plenty of drainage holes, and horticultural grit mixed in at up to a quarter of the volume. Wisconsin Extension says a clay pot works best, and Iowa State notes clay is porous and dries out more readily.
How often should you water rosemary in a pot?
Only when the mix has dried. The RHS notes potting mix “can dry out quickly in hot, dry, sunny weather”, so pots need some water in dry spells. The same page says rosemary must never sit in waterlogged compost, so let every watering drain through and tip out whatever collects in the saucer. Our windowsill herbs guide covers the finger test for checking the mix.
How cold can rosemary take?
We lined up three expert sources and converted the US hardiness zones to Celsius ourselves, using the coldest edge of each zone. The USDA map uses the average annual extreme minimum temperature in Fahrenheit, and we’ve converted every Fahrenheit figure in this post.
| Source | What it says | Coldest point, °C (zone figures use the zone’s coldest edge) |
|---|---|---|
| RHS (UK) | Established plants survive “as low as -8°C” | about -8 |
| NC State Extension | USDA zones 8a to 10b | about -12 |
| Nebraska Extension | Hardy in zones 7 to 10 | about -18 |
| Nebraska Extension | The cultivar ‘Arp’ is “one of the most winter hardy types (Zone 6)” | about -23 |
For rosemary in general, that’s a spread of about 10 °C, from -8 to about -18 °C, and about 15 °C if you count the hardy cultivar ‘Arp’. The comparison isn’t perfectly like-for-like. The RHS gives a temperature a plant can survive, while a USDA zone describes the average coldest night of a place, and cultivars differ.
Wet soil is the other half of the story. Nebraska Extension calls “wet, poorly drained winter soil” the biggest threat to winter survival, and the RHS warns that “cold, wet compost can cause rosemary roots to rot and die.” Roots in pots can freeze through, so the RHS suggests grouping or wrapping pots, or moving them somewhere sheltered and out of the rain.
Can you keep rosemary indoors over winter?
Yes, though NC State and Arkansas extension both say it can be difficult. Wisconsin Extension suggests moving potted plants inside by mid to late autumn, before the first frost.
Light comes first. Iowa State lists rosemary among herbs that need more light than most and/or can have pest trouble like spider mites indoors, and suggests a sunny south-facing window, with bright east or west windows as alternatives. In the Southern Hemisphere the sun sits to the north, so a north-facing window does the same job. NC State adds spider mites, aphids, mealybugs and whiteflies to watch for, particularly indoors.
Temperature matters as much as light. Nebraska Extension says rosemary is happier at 10 to 13 °C if you have a room that cool, and Wisconsin Extension suggests keeping it below about 18 °C and away from heaters.
Indoor watering can go wrong in both directions. An Arkansas extension column calls overwatering “a death knell” indoors. Wisconsin warns that warm, dry winter air “can wither its leaves”, and an Illinois Extension horticulture educator found it dries out quickly and drops leaves. Wisconsin’s check is to push a finger about 2.5 cm into the mix and water thoroughly if it’s dry, and Nebraska’s target is soil kept “evenly moist to slightly dry.”
Salvia rosmarinus or Rosmarinus officinalis?
A 2017 peer-reviewed paper in Taxon by Drew and colleagues recommended treating rosemary as part of the sage genus, and NC State and the RHS now use Salvia rosmarinus, a name that USDA’s GRIN database records as published by Spenner in 1835. GRIN still lists it as a synonym of Rosmarinus officinalis, so either name on a label means the same herb.
How do you prune and harvest rosemary?
After flowering, according to both NC State and the RHS, though their advice on how hard to cut describes different plants. NC State says severe pruning once the bloom has passed is an option to encourage dense growth. The RHS recommends a light yearly trim that avoids old wood, and says old, straggly plants don’t “usually recover from heavy pruning”.
Left unpruned, rosemary becomes leggy and bare at the base, and even with regular trimming the RHS suggests replacing it every seven or eight years. Harvest any time, though the RHS finds the soft new growth of late spring and summer has the best flavour. Arkansas adds that rosemary is stronger fresh than dried, unlike most herbs.
How do you grow rosemary from cuttings?
Rosemary is slow from seed (the RHS says several years to a harvestable plant), so cuttings are the faster route. A master gardener guide from NC State Extension gives a simple method for late spring into summer:
- Cut green, non-flowering tips 7.5 to 13 cm long.
- Strip the lower leaves so only the top 2.5 to 5 cm stays leafy, and trim just below a node.
- Plant in a free-draining mix like perlite, sand or seed-starting mix, under a clear bag.
- Keep it bright but out of full sun and moist, and expect roots in 4 to 6 weeks.
The same guide expects only 30 to 50% of cuttings to root, so take two or three times as many as you need. The RHS also suggests layering, pegging a low stem into the soil to root.
What this means for you
- Drainage first: grit in the mix, holes in the pot, and never leave it sitting in water.
- Choose for your winter: if you get hard frosts, look for a hardy cultivar like ‘Arp’ and keep the roots dry.
- Indoors: bring it in before the first frost and give it the coolest bright window you have.
- Keep a spare: root a few cuttings each summer so an old or lost plant is easy to replace.
What’s the coldest winter your rosemary has come through, and was it in the ground or in a pot? Hit reply and tell us.
How we made this: AI tools helped us research and draft this post. We checked every figure, quote and link against its original source before publishing. Figures are as of 8 November 2026.
Grown with intention by Dynamic Nexus Garden.