What Temperature Can Rosemary Tolerate? Cold & Heat Limits

By Michael Chen · January 24, 2026

Rosemary (Rosmarinus officinalis) can typically tolerate temperatures as low as 10°F (-12°C) for short periods, but prolonged exposure below 20°F (-7°C) may cause damage or death. Hardy in USDA zones 7–10, rosemary thrives best between 60°F and 80°F (15–27°C).

Understanding Rosemary's Temperature Tolerance

Rosemary is a Mediterranean herb that evolved in warm, dry climates with mild winters. While it's considered relatively hardy among culinary herbs, its cold tolerance has limits. Understanding these thresholds helps gardeners grow healthy plants year-round, whether in-ground, in containers, or indoors.

Factors That Influence Cold Hardiness

Duration of cold exposure: Brief dips below freezing are less harmful than sustained cold.
Moisture levels: Wet soil increases root rot risk in cold weather.
Wind exposure: Cold winds accelerate desiccation, especially in evergreen plants like rosemary.
Plant maturity: Established plants tolerate cold better than young ones.
Cultivar type: Some varieties are bred for improved cold resistance.

USDA Hardiness Zones and Rosemary Survival

The USDA Plant Hardiness Zone Map is a key tool for predicting which plants survive winter in your region. Rosemary is generally rated for zones 7 to 10, but microclimates and cultivation methods can expand this range.

USDA Zone	Average Min Temp (°F)	Average Min Temp (°C)	Rosemary Survival Outlook	Recommended Protection
5	-20 to -10°F	-29 to -23°C	Unlikely outdoors	Grow in containers; bring indoors
6	-10 to 0°F	-23 to -18°C	Poor without protection	Mulch heavily; use cold frames
7	0 to 10°F	-18 to -12°C	Fair to good	Mulch roots; shelter from wind
8	10 to 20°F	-12 to -7°C	Good	Minimal protection needed
9	20 to 30°F	-7 to -1°C	Very good	Rarely needs protection
10	30 to 40°F	-1 to 4°C	Excellent	No protection needed

Table data source:USDA, Missouri Botanical Garden

The table shows that rosemary survival correlates strongly with minimum winter temperatures. In zones 7 and 8, proper site selection and root protection significantly improve overwintering success. Gardeners in colder zones (5–6) should treat rosemary as a container plant to move indoors during winter.

Protecting Rosemary in Cold Weather

If you're growing rosemary in a borderline climate, taking preventive steps can mean the difference between survival and loss.

Practical Winter Protection Tips

Mulch around the base: Apply 2–3 inches of straw or bark to insulate roots.
Use windbreaks: Erect barriers to reduce drying winter winds.
Avoid late-season fertilizing: This encourages tender growth vulnerable to frost.
Ensure excellent drainage: Raised beds or sandy soil prevent root rot in winter.
Grow in containers: Potted rosemary can be moved to a garage or sunroom when temperatures drop.

Indoor Overwintering of Rosemary

In regions with harsh winters, bringing rosemary indoors is often the safest option. However, indoor conditions can be challenging due to low humidity and limited light.

Indoor Care Guidelines

Light: Provide at least 6 hours of direct sunlight or use grow lights.
Temperature: Keep between 60–70°F (15–21°C); avoid heat vents.
Watering: Allow soil to dry slightly between waterings; overwatering is a common killer.
Humidity: Mist occasionally or place on a pebble tray to increase moisture.
Pest monitoring: Check regularly for spider mites and whiteflies.

Heat Tolerance and Optimal Growing Temperatures

While cold tolerance is critical, understanding heat limits is equally important. Rosemary thrives in warmth and handles high temperatures well if given adequate airflow and not overwatered.

Optimal range: 60–80°F (15–27°C)
Upper limit: Can tolerate up to 95°F (35°C) with proper care
Extreme heat warning: Above 100°F (38°C), stress increases, especially in dry, windy conditions

In hot climates, provide afternoon shade and ensure good air circulation to prevent fungal issues.

Frequently Asked Questions About Rosemary Temperature Tolerance

Can rosemary survive winter outdoors?

Yes, in USDA zones 7–10, rosemary can survive winter outdoors with minimal protection. In colder zones, it's best grown in containers and brought indoors before the first hard freeze.

What temperature kills rosemary?

Sustained temperatures below 20°F (-7°C) can kill rosemary, especially if roots are wet. Short exposure to 10°F (-12°C) may be survivable for mature, well-established plants with protective mulching.

Should I cover rosemary in a freeze?

Yes, covering rosemary during a hard freeze (below 25°F / -4°C) with a frost cloth or blanket can protect foliage from frost damage. Avoid plastic directly touching leaves; use stakes to create a tent.

Can rosemary tolerate snow?

Rosemary can tolerate light snow if the ground is well-drained and the plant is mature. Heavy, wet snow can break branches, so gently brush it off. The real danger comes from freeze-thaw cycles and ice buildup in soggy soil.

How do I revive frozen rosemary?

Wait until spring to assess damage. Prune only dead stems after new growth appears. Keep soil dry and provide indirect light if indoors. Recovery is possible if the root crown remains firm and white inside.