Rosemary turns brown in March: what to do now

Brown shoots can cause panic in the garden – often for no real reason.

Anyone spotting brown needles in March will immediately suspect frost damage. Yet a browned branch is not necessarily beyond saving. In many cases, it is simply a temporary stress response that can be corrected with a few targeted measures. The crucial factors are the location, water balance and the right time to prune. This way, the shrub will not merely survive but will also grow strongly 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 sun, wind and wet conditions. That exact mixture places it under stress in the UK climate. Sunny days when the ground is frozen are particularly problematic: the foliage loses water through evaporation, while the roots cannot replenish it. Waterlogging in pots and beds with heavy soil creates another issue. Both weaken the plant tissue, making it more vulnerable when overnight frost arrives.

• frost drought: water evaporates while the roots cannot absorb it, causing the needles to dry out
• waterlogging: a saturated root ball is more likely to rot in cold weather
• winter sun: thawing by day followed by freezing at night can rupture cells
• autumn feeding applied too late: soft growth is more susceptible to frost
• variety choice: some rosemary varieties are hardier than others

“Brown needles are often a sign of stress – not a death sentence. Many shrubs produce new growth from wood that appears dead.”

Identifying real frost damage and avoiding a false alarm

How to recognise genuine frost damage

• shoots look glassy, soft or greyish-brown
• the bark comes away easily and there is no green tissue beneath it
• the inside of the branch is brown to black
• needles drop off when touched lightly

Harmless winter stress: how to check 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 inside of the shrub remains healthy
• buds at the shoot tips are beginning to swell

Tip: Hold off on major pruning until fresh green tips are visible. Depending on the region, they may not appear until late March or April.

Rosemary recovery plan for March: what helps now

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

Above all, avoid keeping the soil wet. Rosemary prefers free-draining conditions and a relatively dry root zone. Water can collect in clay or concrete pots without effective drainage holes, leading to tissue damage in frosty weather.

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

Wait until the hardest frosts have passed and new shoots can be seen before cutting back. Use sharp, clean secateurs.

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

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

Position and soil: creating the right conditions

Rosemary thrives in full sun and a sheltered spot. Walls that store warmth can help offset cold nights. Soil must dry out very freely. In beds with clay soil, it is worth incorporating gravel or sand into the planting hole. In a pot, a Mediterranean mix of herb compost, mineral grit and a little sand works well.

• 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

Which rosemary varieties cope well with frost

Variety	Frost tolerance	Notes
Classic culinary rosemary (Rosmarinus officinalis)	low to medium	short periods down to around −8 °C; keep dry and avoid waterlogging
‘Arp’	high	regarded as particularly robust; can withstand lower sub-zero temperatures in a suitable position
‘Blue Winter’	medium to good	more resilient than standard types, but sensitive to wet roots
Creeping rosemary (Rosmarinus prostratus)	low	decorative, but better suited to mild locations 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 often, but thoroughly, and only on mild days
• feeding in late autumn: this produces soft shoots that freeze easily
• a dark winter position: rosemary needs light or it will shed leaves
• hard pruning during frost: this can cause deeper damage and increase fungal risks

Practical check: testing whether the wood is alive

The scratch test can help you decide what to do. Lightly scrape the bark in an inconspicuous place using your thumbnail or a small knife. If the cambium beneath 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 back towards the base. Often, only the tips have been damaged.

When to repot and when to move rosemary

Repot or plant out only in April or May, once the soil has become consistently mild. Choose a pot with drainage holes and add a gravel drainage layer at the bottom. When moving a plant in the 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 briefly

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

Risks and opportunities in late winter

The greatest danger is the shift between mild days and hard nights. Rosemary thaws during sunny afternoons, loses water, then freezes again in the evening. A light layer of horticultural fleece on clear nights, together with a small amount of water at midday, can soften these fluctuations. Those who remain patient now are often rewarded with strongly scented foliage from April onwards.

Practical planting combinations in the bed

Rosemary works well alongside thyme and lavender. All three favour poor, mineral-rich soil and full sunshine. In containers, use layered planting: a drainage layer at the base, mineral-rich compost above it, then a little gravel as a surface mulch. This keeps the root collar dry and reduces fungal problems. In windy gardens, a low hedge of box companions or herbaceous herbs can protect the shrub from drying easterly winds.

Conclusion for gardening in March

Brown tips are no cause for alarm. Check whether there is life in the wood, protect the plant from wind, keep the root ball loose and relatively dry, and only prune once new growth is visible. With a hardy variety and a free-draining position, the rosemary will soon be deep green again – ready to provide fresh sprigs for roast potatoes, marinades and the start of spring barbecues.