The silene family covers a remarkably wide range of garden plants, from Silene dioica, the red campion that lights up UK hedgerows and woodland edges every spring, to cottage garden favourites like Silene coeli-rosa (rose of heaven) and Silene armeria (sweet William catchfly). All are easy to grow and important for pollinators, especially solitary bees. When the leaves start to curl or distort, the cause is almost always identifiable from the pattern and timing of the symptoms. Aphids and the specialist fungal disease anther smut account for most cases, but powdery mildew, leaf miners, root rot, drought, and slug damage can also play a role.
Aphids: the most common cause of curling leaves on silene
From late spring through early summer, aphids are by far the most likely explanation when silene leaves curl downward on the shoot tips and along young stems. Two species are most often involved on campion and catchfly. The stem aphid is a larger, pale-coloured insect that builds colonies directly on the flower stems and petioles of red campion in particular. The peach-potato aphid (Myzus persicae) is a smaller, pale green insect that colonises the shoot tips and newest leaves across a wider range of hosts, including the annual silenes grown in cottage garden borders.
Both species feed by piercing the leaf and stem tissue and extracting sap. The plant responds by rolling the affected leaves downward and inward, which both signals the stress and inadvertently shelters the aphid colony from predators and rain. A close look at the shoot tips of affected plants will reveal the insects themselves, typically in dense clusters. Sticky honeydew coats the foliage below the feeding sites, attracting ants and eventually supporting sooty mould growth. Red campion growing in hedgerows and along woodland edges is especially prone in spring, when populations build rapidly on the flush of new growth before natural predators arrive in numbers.
Treatment on garden plants is straightforward. Rub colonies off by hand on a cool morning when the insects are sluggish, or knock them loose with a firm jet of water from a hose, paying particular attention to the shoot tips and the undersides of curled leaves. Insecticidal soap spray applied to the affected areas is effective for heavier infestations. Wild red campion in hedgerows rarely needs intervention: ladybird, lacewing, and hoverfly larvae arrive in force by early June and bring aphid colonies under control without help. Maintaining good airflow around garden plants by thinning seedlings and avoiding overcrowded borders reduces the conditions in which aphid colonies thrive.
Anther smut: a specialist disease that requires removal, not treatment
Anther smut is one of the most striking and troubling diseases that can affect silene, and it is important to recognise it early because it spreads in a way that is entirely unlike most garden diseases. The fungus responsible, Microbotryum violaceum (historically also classified as Ustilago violacea), is a specialist pathogen of the pink family that has co-evolved specifically with silene and related plants. It subverts the plant's own reproductive system: rather than producing pollen in the anthers, infected plants produce masses of black, powdery fungal spores. The flower looks dark and sooty where it should be dusty with pollen.
The systemic infection causes more than flower distortion. Infected plants also show reduced vigour, distorted leaf growth, and a generally stunted appearance as the disease suppresses normal development. Leaves may curl and yellow as the plant declines. The critical problem with anther smut is how it spreads: pollinators visiting the flowers pick up the spores exactly as they would collect pollen, then deposit them in the flowers of healthy silene plants on the same or subsequent visits. In a garden where several silene species or varieties grow in proximity, a single infected plant can spread the disease across the whole planting within a season.
There is no treatment for anther smut. An infected plant cannot be cured, and chemical sprays have no effect on a systemic fungal infection of this type. Remove infected plants as soon as you identify them, pulling them out by the roots so no regrowth can occur, and dispose of them in the bin rather than the compost heap. The most important step is timing: remove plants before they flower. If the flower buds are already opening and you can see the characteristic black anthers, remove them before any pollinators visit. Where possible, check silene plants regularly from bud formation onwards during the season so that infected individuals can be pulled before spore dispersal begins.
Powdery mildew in dry, hot conditions
Silene plants, particularly the annual cottage garden varieties S. coeli-rosa and S. armeria, can develop powdery mildew during hot, dry spells in summer. The disease appears as a white or pale grey floury coating on the upper surfaces of the leaves, and affected leaves often curl or pucker at the margins as the fungal growth interferes with normal leaf tissue. In the UK, powdery mildew on silene tends to be most common in July and August after prolonged dry periods, especially on plants growing in crowded conditions where air circulation between stems is limited.
Thin seedlings to leave adequate space between plants, which improves airflow and reduces the humidity around foliage that mildew requires to establish. Water at the base of the plants during dry spells rather than overhead, keeping foliage as dry as possible. Remove badly affected leaves and apply a potassium bicarbonate fungicide spray at the first visible sign of white coating. On self-seeding annuals, the simplest long-term strategy is to allow plants to set seed before pulling them at the end of the season, clearing all debris, and letting the next generation germinate into a fresh, uncontaminated position.
Leaf miners and their winding tunnels
Leaf miners are the larvae of various small flies and moths that feed between the upper and lower surfaces of the leaf, creating characteristic pale, winding tunnels that are most obvious when the leaf is held up to the light. On silene, the tunnels cause the surrounding tissue to bubble, pucker, and distort as the larva consumes the internal leaf cells. The leaf surface around the tunnels may curl or lift as the leaf loses structural integrity at the feeding sites. Individual leaves can be badly disfigured, but leaf miner infestations on garden silenes are rarely severe enough to cause significant harm to the whole plant.
No chemical treatment is warranted in most garden situations. Simply remove the worst-affected leaves and discard them in the bin rather than the compost heap, which kills the larvae inside and prevents them completing their lifecycle in the garden. Natural parasitoid wasps provide effective biological control in most UK gardens through the season.
Drought stress and root problems
In prolonged dry weather, silene leaves curl inward along their length as the plant reduces its surface area to limit water loss. This is a stress response rather than a disease symptom, and the leaves typically unfurl within a day or two of rainfall or watering. The annual species S. coeli-rosa and S. armeria are both naturally adapted to well-drained, even dry soils and are more tolerant of drought than many bedding plants, but they still curl and decline if water stress is prolonged through a hot summer.
Root rot in waterlogged or poorly drained soils produces similar wilting and leaf distortion but does not resolve with watering. In fact, waterlogged plants continue to deteriorate even after rain stops. Both annual and perennial silenes prefer free-draining soil, and in heavy clay or low-lying positions, incorporating grit before planting or raising the beds slightly provides better drainage around the root zone. Yellow lower leaves, blackened stem bases, and a foul smell from the soil around the roots indicate root rot rather than drought.
Slugs and snails on young seedlings
Slugs and snails do not cause classic leaf curling, but they can produce ragged, distorted leaf edges on young silene seedlings that are sometimes confused with other problems. The damage is most obvious on seedlings that have just germinated or on transplants in their first few weeks, before the stems toughen. Irregular holes and notched or tattered leaf edges, particularly on the lowest and outermost leaves, combined with slime trails on the foliage or nearby soil, confirm slug or snail feeding. Protect young plants with copper tape around pot rims, collect slugs by torchlight on damp evenings, or apply a wildlife-safe iron phosphate slug pellet around vulnerable seedlings.
Prevention and the case for good spacing
Most leaf problems on silene are significantly reduced by one basic cultural practice: giving plants enough space. Silene self-seeds prolifically, which is one of its great charms in the garden, but dense self-seeded drifts create exactly the crowded, humid conditions that favour aphid colonies, powdery mildew, and the spread of anther smut spores between plants. Thin seedlings to at least 20 to 30 centimetres apart for the annual species, and allow red campion in a naturalistic planting to form loose rather than impenetrable colonies. Grow the annual species in well-drained soil in a sunny position, which suits their Mediterranean origins and keeps the foliage drier than a rich, moist border would. Remove anther-smut-infected plants the moment you identify them, before any pollinators visit the flowers. At the end of each season, clear spent plants and debris rather than leaving them in place, which reduces the overwintering reservoir of both fungal disease and pest eggs for the following year.
Silene as a UK wildlife plant
Red campion and white campion (S. latifolia) are important UK native wildflowers and significant sources of nectar and pollen for bumblebees, solitary bees, and night-flying moths. Red campion flowers from late April through June in its typical hedgerow and woodland-edge habitat, and continues much later in sheltered gardens. The cottage garden annual species extend the flowering season into late summer and are especially valuable for solitary bees seeking late-season forage. Keeping these plants healthy enough to flower freely is worth the effort not just for their own display but for the wildlife that depends on them through the season.
Frequently asked questions
Why are my red campion leaves curling?
The most common cause of curling leaves on red campion (Silene dioica) in spring and early summer is aphid feeding. Stem aphids and peach-potato aphids cluster on the shoot tips and young stems, causing the leaves to roll downward. Check the growing tips for colonies and look for sticky honeydew on the foliage below. Powdery mildew, drought stress, and anther smut are other possibilities worth ruling out.
What is anther smut on silene and how do I recognise it?
Anther smut is a specialist fungal disease caused by Microbotryum violaceum that infects Silene species. Infected plants replace pollen in their anthers with black, sooty spores. The flowers look dark and dusty rather than pollen-dusted, and the leaves distort and the plant loses vigour over time. There is no cure: remove and bin infected plants immediately, before pollinators visit the flowers and carry spores to healthy plants nearby.
Can silene get powdery mildew?
Yes. Silene species, including S. coeli-rosa and S. armeria grown as cottage garden annuals, can develop powdery mildew during hot, dry spells in summer. A white floury coating appears on the upper leaf surfaces and the margins curl or pucker. Improve airflow by thinning seedlings and removing crowded stems, water at the base during dry periods, and apply a potassium bicarbonate spray at the first sign of infection.
Why are there pale winding tunnels on my silene leaves?
Pale, winding tunnels visible against the light are the feeding trails of leaf miner larvae living between the upper and lower surfaces of the leaf. The tunnels cause the surrounding tissue to distort and pucker. Infestations are rarely severe enough on garden silenes to need treatment. Remove the most affected leaves, which kills any larvae inside, and discard them rather than composting.
Does silene self-seed and will problems carry over from year to year?
Yes, most Silene species self-seed prolifically. Red campion and white campion naturalise readily in hedgerows and borders, and the cottage garden annuals S. coeli-rosa and S. armeria return freely from dropped seed. Removing anther-smut-infected plants before they flower prevents spores from spreading to the next generation. Pulling up plants affected by powdery mildew or leaf miners at the end of the season, rather than leaving them to self-seed in situ, limits the carryover of both.