Rosemary turns brown in March: what to do now

Brown shoots can cause alarm in the garden – but there is often no need to worry.

When brown needles appear in March, frost damage is usually the first suspicion. However, a browned shoot is not automatically beyond saving. In many cases, it is a temporary stress response that can be corrected with a few well-chosen measures. Location, water management and the right pruning time are what matter. This will help the shrub survive and grow vigorously again in spring.

Why rosemary turns brown in March

Rosemary originates from the Mediterranean. It can cope with cool nights, but not with a combination of prolonged frost, winter sunshine, wind and wet conditions. This is precisely what puts the plant under pressure in our climate. Sunny days with frozen ground are particularly problematic: the foliage loses water through evaporation, while the roots cannot replenish it. Waterlogging in containers and beds with heavy soil is another issue. Both weaken the tissues, making them more susceptible to damage during night frosts.

• frost drought: evaporation continues while the roots cannot absorb water, causing the needles to dry out
• waterlogging: a wet root ball is more likely to rot in cold weather
• winter sun: thawing during the day followed by freezing at night causes cells to burst
• late autumn fertilising: soft tissue freezes more readily
• variety choice: some rosemary varieties are tougher than others

“Brown needles are often a sign of stress, not a death sentence. Many shrubs grow again from wood that appears dead.”

Identifying genuine frost damage and avoiding false alarms

How to recognise real frost damage

• shoots appear glassy, soft or grey-brown
• the bark comes away easily and there is no green tissue underneath
• the inside of the branch is brown to black
• needles fall off with light contact

Harmless winter stress: checking for new growth

• the needles are brown but still feel firm
• a light scratch reveals green cambium
• only the sunny side is affected, while the centre of the shrub remains healthy
• buds at the shoot tips begin to swell

Tip: Do not make major cuts until fresh green tips are visible. Depending on the region, these may not emerge until late March or April.

Rosemary rescue plan for March: what helps now

• water moderately on frost-free days, especially for plants in pots
• protect the plant from cold easterly winds, for example with horticultural fleece or a screen
• insulate containers using a wooden stand, coir mat or bubble wrap underneath
• do not fertilise until spring has properly begun
• avoid repotting while nights remain severely cold

Above all, prevent the soil from becoming wet. Rosemary prefers free-draining, relatively dry conditions. In clay or concrete pots without effective drainage holes, water can collect and lead to tissue damage in freezing weather.

The right pruning method: when, how deep and with what

Wait to prune until the harshest frosts have passed and new shoots can be seen. Use sharp, clean secateurs.

• cut only into green wood, never into old, thick brown wood
• remove dead, brittle wood completely
• rejuvenate heavily aged sections gradually, preferably over two years
• do not fertilise immediately after pruning; wait until growth has become stable

“The best time to prune is early spring. Moderate shaping encourages dense new growth and prevents bare patches.”

Location and soil: creating the right conditions

Rosemary thrives in full sun and a sheltered position. Heat-retaining walls can help balance out cold nights. The soil must dry out very well. In beds with loamy soil, adding a gravel or sand mix to the planting hole is worthwhile. In pots, use a Mediterranean mix of herb compost, mineral granules and a little sand.

• sunny, warm and sheltered
• free-draining growing medium with a high mineral content
• container drainage: place coarse gravel over the drainage hole
• water sparingly and never keep permanently damp

Rosemary varieties that cope well with frost

Variety	Frost tolerance	Notes
classic culinary rosemary (Rosmarinus officinalis)	low to moderate	short periods down to around −8 °C; keep dry and avoid waterlogging
‘Arp’	high	considered particularly hardy; can tolerate lower sub-zero temperatures in a good location
‘Blue Winter’	moderate to good	sturdier than standard varieties, but sensitive to wet roots
trailing rosemary (Rosmarinus prostratus)	low	decorative, but better suited to mild areas or pots with winter protection
‘Veitshöchheim Rosemary’	good	proven in Central Europe; free-draining soil is essential

Common mistakes and how to avoid them

• too much water in winter: water less frequently, but thoroughly and only on mild days
• fertilising in late autumn: encourages soft shoots that freeze easily
• a dark winter position: rosemary needs light or it will shed leaves
• severe pruning during frost: increases deeper damage and the risk of fungal problems

Practical check: testing whether the wood is alive

The scratch test helps when deciding what to do. Lightly scratch the bark in an inconspicuous place with a thumbnail or small knife. If the cambium is fresh green, the shoot is alive. If it is brown and dry, it can be removed later. Check several points, working from the shoot tip towards the base. Often, only the tips are damaged.

When to repot or move rosemary

Only repot or replant in April or May, once the soil is consistently mild. Choose a container with drainage and add a gravel drainage layer at the base. If moving a plant in a bed, prepare a planting hole rich in gravel. After relocating it, provide shade and wind protection until the shrub is taking up water strongly again.

Key terms explained

• frost drought: water loss through leaves when the ground is frozen, resulting in brown needles
• waterlogging: water remains around the roots, displaces oxygen and promotes rot
• green wood: the area that still contains living tissue and can produce new growth

Risks and opportunities in late winter

The greatest risk comes from alternations between mild days and hard frosts at night. Rosemary thaws on sunny afternoons, loses water and freezes again in the evening. A light layer of horticultural fleece on clear nights, together with a small amount of water at midday, helps cushion these fluctuations. Those who remain patient now are often rewarded with strongly scented foliage from April.

Practical bed combinations

Rosemary combines well with thyme and lavender. All three prefer lean, mineral soil and full sun. In containers, a layered arrangement works well: a drainage layer at the bottom, then mineral-rich compost, finished with a little gravel as mulch. This keeps the root crown dry and reduces fungal infection. In windy gardens, a low hedge of boxwood companion plants or herbaceous perennials protects the shrub from drying easterly winds.

Conclusion for garden practice in March

Brown tips are not a disaster. Check whether the wood is alive, protect the plant from wind, keep the root ball loose and on the dry side, and prune only once new growth is visible. With a hardy variety and a free-draining site, the rosemary will soon be deep green again – ready to provide fresh sprigs for roast potatoes, marinades and the start of the spring barbecue season.