Lamb's ears (Stachys byzantina) is one of the most beautiful and tactile plants you can grow in a UK border. The silvery, densely woolly leaves that give the plant its name are extraordinary to touch, irresistible to children, and genuinely unlike anything else in a mixed planting. Native to the dry hillsides of Turkey, Armenia, and Iran, it is completely hardy in the UK and thrives on thin, poor, sunny soil where many other perennials give up.
But those same felted leaves that make it so remarkable are also its vulnerability. When the woolly surface traps moisture and air cannot circulate freely, fungal rot can take hold fast. Curling, collapsing, or browning leaves on lamb's ears are most often a drainage and air circulation problem, not a pest problem. Identifying which issue you have determines what action to take.
Wet rot at the crown: the most common cause
By a wide margin, the most frequent reason lamb's ears leaves curl and collapse in the UK is wet rot, caused by Botrytis cinerea and related fungal pathogens. The mechanism is straightforward. The woolly texture of the leaves, which is an adaptation to reduce water loss in the plant's dry native habitat, creates a dense mat that holds moisture against the crown when conditions are wet. In a UK winter, or during a prolonged rainy spell on heavy soil, that trapped moisture is enough for fungal rot to establish in the centre of the rosette.
The early sign is leaves at the centre of the rosette that look pinched or pressed together rather than spreading outward. As rot progresses they turn pale tan, then brown, then collapse into a slimy mass. The surrounding outer leaves may still look healthy for a time, which can make the problem look worse than expected when you examine the crown closely.
Prevention is the key because once the crown is heavily infected, the plant cannot easily be saved in situ. Plant lamb's ears in very free-draining soil, ideally with coarse grit worked in before planting. On heavy clay, use raised beds or plant on slopes where water drains away naturally. Do not mulch around the crown: bark, leaf mould, and similar mulches hold moisture against the base of the plant and increase rot risk sharply. Deadhead the flower spikes promptly after flowering, since the upright spikes shade the crown and restrict air movement around the rosettes below.
If you catch rot early, cut away all infected material with clean scissors or a knife, removing leaves back to healthy tissue. Lift and divide the plant, discard any soft or discoloured crown sections, and replant in a fresh, very gritty position in full sun. Spreading out the divisions so they have space between them allows air to move freely and substantially reduces reinfection risk.
Drought stress and heat
Established lamb's ears is genuinely drought-tolerant. The silvery felt on the leaf surface is not just decorative: it reflects heat and sunlight, reduces the leaf surface temperature, and cuts water loss through the leaf cuticle. This is exactly why the plant evolved this appearance in a semi-arid climate. In a normal UK summer it will thrive on rainfall alone once the roots are established.
However, young plants installed within the last growing season, and plants in containers with limited compost volume, can show leaf margin curling and wilting in very prolonged dry spells or during exceptional heat. The margins roll inward as the leaf attempts to reduce its exposed surface area and conserve moisture. Unlike the central collapse caused by wet rot, drought curl affects the outer leaf margins first and the leaves feel dry and papery rather than slimy.
When drought stress is the cause, water at the base of the plant only. Overhead watering on lamb's ears is counterproductive because wet woolly leaves are precisely the condition that encourages the fungal rot described above. Water in the evening to reduce evaporation loss. Established plants in open ground recover rapidly, often within hours of a good soak. If a container plant shows repeated drought stress, move it to a slightly less exposed position or increase compost volume by potting on.
Other causes worth checking
Vine weevil grubs are worth investigating if containerised lamb's ears shows general wilting and crown curl without any visible rot. Adult vine weevils lay eggs in the compost and the cream-coloured C-shaped grubs feed on the roots through autumn and winter. By spring, the root system can be so severely damaged that the plant cannot take up water even when the compost is moist. Tip the plant out of its pot in spring and inspect the root ball. If grubs are present, remove and destroy them, trim back any damaged roots, and repot in fresh compost.
Aphids occasionally colonise the flower spikes of lamb's ears, particularly in late spring. They rarely attack the leaves directly but can cause the spikes to distort and the bracts at the base of the flower to cup inward. Knock them off with a jet of water or remove the affected spikes entirely, which also helps with air circulation around the rosettes.
Powdery mildew can appear on lamb's ears in humid late summers, particularly on crowded clumps with poor air circulation. On the felted leaves it can be harder to spot than on smooth-leaved plants, but look for a dull or flattened appearance to the leaf surface and check the flower stalks for white powdery patches. Cutting the clump back hard refreshes the plant and removes infected material.
Slugs are attracted to the microclimate of humidity trapped beneath the woolly leaves and can damage the felted surface, leaving ragged holes or stripped areas that cause the leaf to curl around the wound. Check beneath the leaves at night if damage appears overnight. Rabbits browse the soft foliage and can strip a clump quickly, but the plant usually regrows unless the crown is repeatedly grazed.
Prevention and long-term care
The fundamentals for healthy lamb's ears come down to three things: drainage, sunlight, and air. Plant in full sun, since even partial shade produces softer, less silvery growth that is more vulnerable to fungal disease. Ensure very free-draining soil, adding coarse grit before planting and choosing raised positions on any site that holds water. Keep the crown clear of mulch, debris, and crowding from neighbouring plants so air moves freely around the rosettes.
Divide congested clumps every two to three years in spring. As the plant spreads and the rosettes press together, air circulation diminishes and rot risk increases. Division also renews the plant: older central portions often become woody and less silvery, while divisions from around the edge are young, vigorous, and beautifully felted.
Cut back tatty or frost-damaged growth in spring to reveal the fresh rosettes emerging from below. Remove spent flower spikes promptly after flowering. The cultivar Silver Carpet, which does not flower at all, is particularly low-maintenance because it never produces spikes and stays compact all season. The cultivar Big Ears (also sold as Helene von Stein) has noticeably larger leaves and is equally worth seeking out for bolder textural contrast.
In the right position, lamb's ears is one of the most maintenance-free and rewarding perennials in the UK garden. Its silver mat looks good from the moment it appears in spring to the first hard frosts. It edges paths beautifully, knits together well with roses and other sun-loving perennials, and provides a textural counterpoint that few other plants can match. Given free-draining soil and full sun, it asks for almost nothing in return.
Frequently asked questions
Why is the centre of my lamb's ears rosette rotting and turning brown?
This is by far the most common problem with Stachys byzantina in the UK and is caused by wet rot, usually Botrytis or a related fungal pathogen, in conditions of poor drainage or persistent humidity. The densely woolly leaves trap moisture at the crown and prevent air from circulating between them. Leaves at the centre of the rosette collapse inward, turn brown and slimy, and the whole crown can be lost in a wet winter. Remove all affected leaves immediately, lift and divide the plant, and replant in very free-draining soil with added grit. Do not mulch around the crown, and avoid planting in low spots where water collects.
Should I remove the flower spikes on lamb's ears?
Many gardeners do remove them, and for good reason. The tall flower spikes shade and crowd the leaf rosettes below, trapping moisture and reducing air circulation, which directly increases the risk of wet rot. The cultivar Silver Carpet is non-flowering and is specifically chosen for groundcover because it never produces spikes and remains compact. If you want to encourage bees, leave some spikes and cut them back after flowering has finished. Otherwise deadheading promptly is a sensible disease-prevention measure.
Can lamb's ears survive in clay soil?
Stachys byzantina really struggles in heavy clay, especially in the UK where clay soils typically stay wet through winter. The plant originates from the dry, rocky hillsides of Turkey, Armenia, and Iran and expects very fast drainage. On clay, plant in raised beds where the crown sits above the surrounding soil level, add plenty of coarse grit, and avoid any low-lying spots. Even with these precautions, on heavy, persistently wet clay the plant is unlikely to thrive long-term. Thin stony or chalky soils suit it far better.
Why are the leaf margins on my lamb's ears curling and wilting?
Margin curl and wilting without central rot points to drought stress or heat, particularly in young or container-grown plants. Despite being drought-tolerant once established, Stachys byzantina can show leaf margin curl in very prolonged dry spells, especially on plants installed within the last year. Water at the base of the plant only, never overhead, as wet woolly leaves encourage the fungal rot that is the plant's main enemy. Water in the evening. Established plants in the ground recover quickly once watered.
When is the best time to cut back tatty lamb's ears?
Spring is the ideal time. Cut back any dead, tatty, or damaged leaves to reveal the fresh new rosettes emerging from the crown. This improves air circulation, removes overwintered fungal material, and gives the plant a clean start. A further tidy in midsummer, removing spent flower spikes and any yellowing outer leaves, keeps the planting looking its best through the rest of the season. Dividing congested clumps every two to three years in spring also refreshes the plant and reduces rot risk.