Can a Rosemary Plant Survive Winter? Tips for Overwintering

With its aromatic pine-like fragrance and flavor rosemary is a delightful herb to grow in the garden. However this Mediterranean native can struggle to survive harsh winters in some climates. If you live in an area with cold snowy winters, special care is needed to help your rosemary plants make it through to spring.

While rosemary is technically rated for USDA hardiness zones 8-10 there are certain techniques gardeners can use to successfully overwinter rosemary in cooler zones down to 6. Follow these tips to give your plants the best chance of surviving winter.

Choosing Cold-Hardy Varieties

Rosemary comes in many different cultivars, and some are more cold tolerant than others. Seek out the following winter-hardy varieties if overwintering rosemary in your area:

• Arp – The most cold-hardy rosemary, rated down to zone 6.

• Madeline Hill – Tolerates zone 6 winters.

• Athens Blue Spire – Survives zone 6 with protection.

• Alcalde – Rated for zone 7 but can handle zone 6 sometimes.

• Hill Hardy – This upright variety handles zone 7.

• Gorizia – Survives winters in zones 7-8.

• Tuscan Blue – Overwinters in zones 7-9.

Look for young plants of these cold-tolerant cultivars to give your rosemary the best winter survival odds. Avoid bringing home leggy, rootbound plants.

Location, Location, Location

Where you situate rosemary plants in your landscape impacts how well they’ll hold up to winter. For best results:

• Plant near the south or west walls of your home where warmth radiates out on cold nights.

• Choose spots protected from harsh winds, which can damage or kill plants.

• Ensure the soil drains well to prevent root rot issues. Add compost to improve drainage.

• In pots, use terra cotta over plastic which stays wet and can crack in freezing temperatures.

Position rosemary where it will be sheltered by your home on multiple sides for optimal winter protection.

Mulch For Insulation

One of the best things you can do to help rosemary plants survive winter is mulch them heavily after the first hard frost. Pile chopped leaves, straw, wood chips, or other organic material around the base to insulate the roots and crown.

• Mulch small plants with 4-6 inches of material.

• For larger bushes, use up to 8-10 inches of mulch.

• The mulch should not touch the stems to prevent rotting.

Check that the mulch hasn’t compressed or blown away and refresh as needed through winter. Rake it back in spring.

Row Covers or Cold Frames

Row covers and cold frames give plants an extra layer of frost and wind protection.

• Drape row covers over plants and secure the edges with ground staples. Use heavyweight fabric for cold regions.

• Cold frames are bottomless boxes with a transparent top that trap heat. Place over rosemary and vent on sunny days.

Erect row covers or cold frames around rosemary before freezing weather arrives in fall. Remove them in spring once temperatures are reliably above freezing.

Prune For Protection

Pruning rosemary plants in fall helps concentrate their energy in the most vital areas for winter survival:

• Prune leggy growth in early fall so plants direct energy to the main stems and roots.

• After the first frost, cut back plants by a third to half. This removes vulnerable new growth.

• In extreme cold, prune plants down to 6 inches above the ground and mulch deeply over the stubs.

Hold off on spring pruning until new growth emerges and any winter dieback can be removed. Avoid pruning rosemary too heavily.

Potted Rosemary

Rosemary grown in containers needs extra protection to survive winter:

• Insulate the pot by wrapping it in burlap, bubble wrap, or insulation.

• Place the pot on bricks or feet to prevent the frozen ground from cracking it.

• Move potted rosemary into an unheated garage or enclosed porch for shelter if possible.

• Water sparingly over winter, just enough to prevent severe drying out.

• Prune plants back before bringing pots indoors to avoid leggy, sparse growth all winter.

Overwinter Indoors

In climates below zone 6, overwintering rosemary indoors is often the only way to keep plants alive.

• Dig up plants and repot into containers before frost. Try to keep large root balls intact.

• Take 6-8 inch stem cuttings in late summer. Root them in water or soil indoors.

• Provide 6-8 hours of sun from a south window or grow lights.

• Water only when soil is partly dry. High humidity helps prevent leaf browning.

• Transition plants outside slowly in spring once nighttime temperatures are above freezing.

Winter Protection Tips

• Cover plants with burlap or old blankets if extreme cold is forecast.

• Place cardboard around exposed sides of container plants for insulation.

• Check for rodent damage and treat young bark with white latex paint diluted with water.

• Remove mulch or row covers promptly in spring so plants can emerge.

• Hold off fertilizing until new growth appears, as extra nitrogen makes plants more susceptible to cold damage.

Signs of Trouble

Check on rosemary frequently over winter. Yellow or dried foliage and shriveled stems may indicate:

• Damage from severe cold – Try added insulation.

• Underwatering – Water when partly dry.

• Overwatering – Allow soil to dry out.

• Lack of humidity – Mist leaves or use a pebble tray.

• Insufficient light – Provide supplemental lighting.

Reviving Frost Damaged Rosemary

If rosemary shows dieback or stark white damaged areas after a harsh cold snap, don’t give up too soon.

• Leave damaged plants in place until spring to see if new shoots emerge from undamaged areas below ground.

• Prune away all shriveled dead sections to just above healthy wood.

• Shelter regenerating plants with row covers to protect tender new growth.

• Water thoroughly if the ground thawed and roots suffered freeze damage.

Particularly hardy varieties in protected locations can sometimes regenerate even from extreme frost or freeze damage.

Enjoy Rosemary Year-Round

While rosemary prefers warm conditions, gardeners in cold winter areas can still keep plants thriving year-round. Choose the right varieties, proper care, ideal placement, and winter protection to help rosemary survive winter. With the right techniques, you can continue enjoying homegrown rosemary’s pine-like flavor all season long.