Bay laurel (Laurus nobilis) is a cherished evergreen shrub or tree, widely recognized for its aromatic leaves that add a distinct flavor to various culinary dishes. Its rich history and ornamental appeal make it a popular choice in many gardens. A common concern for gardeners is the bay laurel’s susceptibility to cold temperatures, necessitating protective measures in many climates.
Understanding Bay Laurel Cold Hardiness
Cold hardiness refers to a plant’s ability to withstand low temperatures. As an evergreen, bay laurel retains its leaves year-round, making it vulnerable to freezing conditions. It is generally hardy in USDA Plant Hardiness Zones 7 to 10, which indicate the average annual extreme minimum winter temperature. For example, Zone 7 can experience minimum temperatures down to 0°F (-18°C), while Zone 10 has minimums around 30°F (-1°C).
Bay laurel can tolerate brief periods of frost, with some varieties handling temperatures down to about 20°F (-6°C), but prolonged exposure below freezing can be damaging. A plant’s individual hardiness is also influenced by its age, overall health, and establishment in the ground.
Identifying Cold Damage
When bay laurel experiences cold stress, it exhibits visual symptoms. Leaves may turn brown or black, wilt, or drop prematurely. This discoloration often appears on leaf tips and edges, sometimes progressing to the entire leaf. In more severe cases, stems and branches can suffer dieback, indicated by a blackened or dull, mottled appearance, and the bark may crack or peel. These signs of damage may not be immediately apparent after a cold snap, sometimes developing over several days or weeks.
Protecting Bay Laurel from Winter Cold
Protecting bay laurel from winter cold requires different approaches depending on whether the plant is in a pot or planted directly in the ground.
Potted Bay Laurels
For potted bay laurels, move them indoors to a cool, bright location before temperatures consistently drop below 50°F (10°C). An unheated garage, shed, or a cool room with indirect light, ideally below 60°F (15°C), is suitable. While indoors, reduce watering frequency, allowing the soil to dry slightly between waterings, and avoid fertilizing until warmer temperatures return. If moving large pots indoors is not feasible, insulate the container by wrapping it with bubble wrap or an old blanket. Apply a thick layer of mulch (4-6 inches) over the soil surface to protect the roots from freezing, and raise pots off the ground using pot feet or bricks to prevent waterlogging and frost damage.
In-Ground Bay Laurels
For bay laurels planted in the ground, select a site protected from strong winter winds with excellent drainage. Apply a substantial layer of organic mulch, such as bark chips or straw, 2 to 6 inches deep around the base of the plant, extending to its drip line, to insulate the root zone. During extreme cold events, cover the plant with burlap, frost cloth, or old sheets, ensuring the material extends to the ground and is secured to trap warmer air. Watering the plant deeply in late autumn before the soil freezes can also help insulate the roots, as moist soil retains heat more effectively than dry soil.
Post-Winter Recovery
After winter, bay laurels showing signs of damage require care to aid their recovery. Be patient and avoid immediately pruning away seemingly dead branches. Wait until new growth emerges in late spring or early summer, typically when leaf buds swell. This new growth indicates healthy tissue, allowing for a more accurate assessment of damaged areas.
Using clean, sharp shears, prune away any blackened, brown, or dead leaves and stem tips, cutting back to just above healthy buds or where green tissue is present. For severely damaged plants, a hard prune back to healthy wood or near ground level may be necessary, as bay laurels can often resprout from the root.
Ensure the plant receives adequate watering during its recovery, allowing the soil to dry slightly between waterings. A balanced organic fertilizer can be applied in spring to encourage new growth once active growth resumes.