Will Rosemary Grow Back After Freeze? What You Need To Know

Freezing temperatures can damage many plants, including rosemary. As a Mediterranean herb, rosemary thrives in warm climates and struggles in cold weather. So what happens when the temperatures dip below freezing? Will rosemary grow back after a freeze?

The short answer is maybe. Rosemary can survive light freezes, but harsh, extended freezes may kill the entire plant. The good news is that with proper care, rosemary stands a fighting chance against cold snaps. This article will cover:

• How cold hardy rosemary is
• Factors that affect freeze survival
• Caring for rosemary after a freeze
• Getting damaged rosemary to regrow

Let’s dive in!

How Cold Hardy is Rosemary?

Rosemary is considered semi-hardy, meaning it can withstand some cold conditions but not harsh winters. Most rosemary varieties tolerate temperatures down to 10-15°F (-12 to -9°C). However rosemary leaves and flowers will sustain damage at 25-30°F (-4 to -1°C).

Prolonged freezes below 15°F put the entire plant at risk. The roots are especially vulnerable to deep freezes. If the roots freeze and die, the rest of the plant will soon follow.

Luckily, rosemary grown in-ground has a better chance of surviving than container plants. The insulating soil protects the roots from frosty conditions.

Factors That Affect Rosemary’s Freeze Tolerance

Several variables determine how well rosemary handles freezing weather:

• Rosemary variety – Some cultivars have higher cold tolerance than others. ‘Arp’ and ‘Madeline Hill’ withstand freezing better than ‘Tuscan Blue’ and other types.

• Plant size & maturity – Younger, smaller plants are more susceptible to freeze damage. Mature, well-established rosemary bushes have a higher survival rate.

• Growing conditions – Rosemary grown in poor, sandy soil or cramped containers struggles more in cold weather. Proper care makes rosemary more resilient.

• Previous cold exposure – Rosemary that has experienced cold conditions can better tolerate future freezes. Prior cold exposure boosts the plant’s defenses.

• Freeze duration – Brief freezes are less damaging than extended sub-zero temperatures. Prolonged deep freezes often kill rosemary.

• Temperature fluctuations – Frequent temperature swings before/after a freeze make matters worse. Stable conditions help rosemary cope.

Caring For Rosemary After a Freeze

If your rosemary was exposed to freezing weather, prompt aftercare can speed its recovery. Here are some post-freeze rosemary care tips:

• Leave dead growth in place – Don’t prune freeze-damaged leaves/stems right away. The dead growth insulates the plant against further cold exposure.

• Check for root damage – Probe the soil around the roots. If it’s mushy, the roots likely froze and rotted. The plant cannot be saved if the roots are dead.

• Shelter in place – Cover rosemary with a frost blanket or burlap to protect it from follow-up freezes. Avoid plastic sheets that trap in moisture.

• Water carefully – Don’t overwater frozen rosemary; excessive moisture promotes rot. Wait until the soil is partly dry before watering again.

• Fertilize lightly – A dilute, balanced fertilizer can help damaged rosemary recover. But go easy; too much nitrogen pushes tender new growth prone to freezing.

• Prune selectively – In early spring, remove dead stems/leaves to make way for new growth. Retain any healthy tissue that insulates the plant.

• Monitor for pests/disease – Weakened, frozen rosemary is prime breeding ground for pests and infections. Watch closely and take action at the first signs.

With attentive care, mildly frozen rosemary often regrows once warmer weather returns. But what if the freeze kills most or all of the top growth?

Getting Damaged Rosemary to Regrow

If a severe freeze kills back your rosemary significantly, all hope is not lost. Here are some tips to revive frozen rosemary bushes:

• Scrutinize the roots – Check the roots again in early spring. If the soil is dry and roots firm, the plant still has life left.

• Cut back dead wood – Prune away all dead, brittle wood, leaving just above live growth or roots. This forces new shoots.

• Fertilize & water – Feed with a balanced fertilizer to energize regrowth. Water when the top few inches of soil become dry.

• Protect new shoots – Cover emerging shoots if additional freezes threaten. Use a cold frame, cloche, or fabric row cover.

• Be patient – It takes time for extensively damaged rosemary to recover. Monitor progress, but don’t expect an overnight rebound.

• Try propagation – Take cuttings from live tissue and root them. This essentially restarts the plant.

With time and TLC, some “dead” rosemary plants do resurrect from remaining healthy tissue. But results vary; success is not guaranteed.

Key Takeaways

To recap, freeze survival outcomes for rosemary depend on many variables. Here are the key takeaways:

• Most rosemary withstands temperatures down to 10-15°F if properly hardened off.

• Bigger, mature rosemary bushes fare better in freezing weather than smaller plants.

• Quick protective action after a freeze gives rosemary the best chance to regrow.

• Severely frozen rosemary may recover from remaining healthy roots and wood.

• Harsh, extended deep freezes often kill rosemary entirely.

While not 100% cold hardy, rosemary can persevere through milder winter conditions. Knowledgeable care and prompt action after freezes improve its odds. With patience and persistence, new growth can spring forth again after frost ravages rosemary.