Why Are My Echium Leaves Curling?

Aphid infestation

Aphids are the most common pest on echium. They colonise the soft young shoot tips and the undersides of the narrow, bristly leaves, particularly on the developing flower spikes before the florets open. Green aphids and black bean aphid are both found on echium. The coarse, bristly hairs on the leaves can make it harder to spot aphid colonies until they are well established. Aphid feeding causes the leaf tips and developing flower spikes to curl and distort, and the flower buds may fail to develop normally in heavy infestations.

What to do

• Check the developing shoot tips and the undersides of young leaves regularly from late spring. Pay particular attention to the tender growing tips of the flower spikes.
• Spray with insecticidal soap every four to five days for two to three weeks. Apply in the evening to avoid harming the bees that visit echium flowers constantly during the day.
• A jet of water dislodges aphids from the bristly leaf surface effectively as a first response.
• Avoid high-nitrogen feeding: echium actually performs best in poor, free-draining conditions and excess fertility produces lush growth attractive to aphids.

Drought stress

Drought stress is one of the most characteristic problems for echium, particularly in containers or in light, very free-draining soil during a prolonged dry spell. Echium vulgare is a plant of chalk downland, roadsides, and dry grassland and tolerates considerable drought once established in the ground, but the coarse leaves curl inward during extended dry periods. Container-grown echium is much more susceptible, as the limited compost volume provides little buffer against hot, dry conditions. Drought during the flowering period causes the flower spikes to shorten and the individual florets to be smaller than normal.

What to do

• Established border echium requires watering only during prolonged drought. Its deep tap root accesses soil moisture unavailable to shallower-rooted plants.
• Container-grown echium needs more frequent watering: check the compost every two to three days in warm weather and water when the top 3 to 4 cm has dried.
• Mulch around border plants to retain moisture, particularly during the first summer after planting when the tap root is not yet fully established.

Overwatering

Overwatering is a common problem for echium in containers or in heavy clay soil. Echium's deep tap root deteriorates rapidly in persistently waterlogged conditions, and the leaves yellow, curl, and the plant declines from the base upwards. In the open ground, echium in heavy clay that drains poorly during a wet UK summer shows exactly this pattern. It performs very poorly in waterlogged conditions and is best avoided in low-lying, poorly drained positions.

What to do

• Plant echium in the most free-draining soil available. It thrives in poor, chalky, sandy, or gravelly conditions. Improve heavy clay drainage with coarse grit before planting.
• In containers, use a very free-draining compost blended with significant amounts of perlite or coarse grit. Ensure excellent drainage holes.
• Reduce watering during cool or wet periods. In the open ground, established echium on well-drained soil rarely needs additional watering in a normal UK summer.

Cold stress

Cold stress causes echium leaves to curl in spring or during unseasonal cold spells. The annual Echium plantagineum types are half-hardy and can be damaged by late frosts, causing the leaves to blacken and curl. Echium vulgare is hardier and tolerates UK winters well as a rosette, but the developing flower spikes in late spring can be damaged by a hard frost if the plants are growing in an exposed position. Frost-damaged spike tips brown and curl but the plant usually recovers and produces replacement flowering stems.

What to do

• For annual echium plantagineum types, do not plant outside until the last frost has passed in late May.
• In exposed positions, protect young flower spikes from unexpected late frosts in April and May with horticultural fleece.
• Echium vulgare that has had its first flower spikes frosted will usually produce replacement spikes and flower well once temperatures stabilise.

Powdery mildew

Powdery mildew occasionally affects echium, particularly the lower leaves on established plants in late summer when conditions become warmer and more humid. The coarse, bristly leaves develop a white powdery coating and curl slightly. It is rarely severe enough to cause serious damage and is mainly a cosmetic problem on the lower, older leaves that are no longer producing food for the plant at that stage of the season.

What to do

• Remove badly affected lower leaves and bin them. The upper foliage and flower spikes are usually unaffected.
• Improve air circulation if echium is crowded by neighbouring plants: space at 45 to 60 cm in borders.
• Spray with a sulphur-based fungicide if mildew spreads to the upper leaves or flower spikes.

Frequently asked questions

Why are my echium leaves curling?

Echium leaves curl most often from aphid infestation or drought stress. Aphids cluster on the shoot tips and the undersides of the narrow, bristly leaves, causing them to curl and the growing tips to distort. Drought causes the coarse, hairy leaves to curl inward as the plant conserves moisture. Echium vulgare in particular is adapted to dry, open conditions and becomes stressed only in prolonged drought or in containers with poor watering.

Is echium biennial or annual?

Echium vulgare, viper's bugloss, is a biennial or short-lived perennial in the UK: it forms a rosette in its first year and flowers in its second. Echium plantagineum and its cultivars (commonly sold as 'Viper's Bugloss' annual types) are half-hardy annuals that can be sown and flowered in the same season. Both are valuable pollinator plants, attracting bumblebees, honeybees, and many solitary bee species.

When should I sow echium?

Sow biennial echium vulgare in late spring to early summer and overwinter the rosettes for flowering the following year. Sow annual echium plantagineum types in autumn for an early spring display, or in early spring where winters are harsh. Both types germinate readily in cool conditions and dislike root disturbance, so direct sowing or sowing in root trainers is preferable.

Does echium self-seed?

Yes, echium self-seeds freely and prolifically once established. In a favourable position, echium can naturalise and spread to fill large areas over several years. The seeds are small and hard-coated and germinate reliably in autumn on bare soil. If you want to control the spread, deadhead promptly after flowering, though leaving some seed heads provides additional food for birds.