Why Are My Anagallis Leaves Curling?

Aphid infestation

Aphids are the most common pest on anagallis. They colonise the shoot tips and the undersides of the small, oval leaves, causing them to curl and distort. Green peach aphid is most commonly found on anagallis. The low, spreading habit of anagallis means aphid colonies on the shoot tips are close to the ground and can be missed until the damage becomes significant. Heavy infestations cause considerable distortion of the young shoot tips and can suppress flowering.

What to do

• Check the shoot tips and leaf undersides regularly, getting close to the ground-level foliage where aphid colonies develop on the spreading stems.
• Spray with insecticidal soap every four to five days for two to three weeks, covering the small leaves and shoot tips thoroughly.
• A jet of water dislodges aphids from the smooth, oval leaves effectively.
• Avoid high-nitrogen feeding which produces soft, lush growth that is particularly attractive to aphids.

Overwatering

Overwatering is one of the most common causes of anagallis decline in containers or in poorly drained soil. Anagallis is a plant of well-drained, relatively poor soil and the fine, spreading root system deteriorates rapidly in persistently wet conditions. The small, oval leaves yellow and curl, and the spreading stems may collapse at their bases. In UK container gardening, anagallis on a fixed watering schedule during cool, overcast periods is particularly at risk of overwatering. This is more often the problem than drought in typical UK summer conditions.

What to do

• Plant anagallis in well-drained, relatively poor soil. It does not need rich, heavily improved conditions and performs better in leaner soil.
• In containers, use a free-draining compost blended with perlite or grit. Ensure excellent drainage holes and allow the compost to dry slightly between waterings.
• Reduce watering frequency during cool, overcast, or wet periods: anagallis in cool, dull weather uses very little water.

Drought stress

While anagallis prefers well-drained conditions, it still needs adequate moisture to flower well, particularly in containers where the limited compost volume dries rapidly in warm weather. The small leaves curl inward and the plant's spreading stems wilt during severe drought. In the open ground in well-drained soil, anagallis in a typical UK summer rarely suffers from drought, but container plants need regular monitoring during warm spells.

What to do

• Water container anagallis when the compost has dried to 2 to 3 cm depth. In warm weather this may mean watering every two to three days.
• Border plants rarely need additional watering in UK conditions but may need watering during prolonged hot, dry spells in summer.
• Mulch around border plants to retain moisture, particularly during their first season when the root system is not yet fully established.

Cold stress

Cold stress causes anagallis leaves to curl and the plant to stall. Anagallis monelli is a half-hardy plant from the Mediterranean and is damaged by frost and by consistent cold below 10 degrees Celsius. Cold causes the small, oval leaves to curl, pale, and take on a slightly bleached appearance, and the plant's growth and flowering stops until temperatures recover. Plants placed outside too early after the last frost may look sickly for weeks before conditions improve.

What to do

• Do not plant anagallis monelli outside until late May or early June when nighttime temperatures are reliably above 10 degrees Celsius.
• Harden off carefully for ten to fourteen days before planting outside.
• Choose a warm, sheltered, sunny position. Cold-stressed plants usually recover well once temperatures improve.

Powdery mildew

Powdery mildew occasionally affects anagallis in warm, dry or humid conditions. The small, oval leaves develop a white powdery coating and curl slightly. It is most common on crowded plants in poor air circulation or on those that have been drought-stressed. By the time powdery mildew is significant, anagallis plants are usually already in the later part of their natural season.

What to do

• Space anagallis plants at 20 to 25 cm to ensure adequate air circulation between the spreading stems.
• Remove and bin affected leaves. Spray healthy growth with a sulphur-based fungicide at the first signs of infection.
• Ensure adequate watering: drought-stressed plants are more susceptible to powdery mildew than well-watered ones.

Frequently asked questions

Why are my anagallis leaves curling?

Anagallis leaves curl most often from aphid infestation or overwatering. Aphids colonise the shoot tips and the undersides of the small, oval leaves, causing them to curl and distort. Overwatering in poorly drained soil or containers causes the leaves to yellow and curl as the fine, spreading root system deteriorates. Anagallis is more susceptible to overwatering than drought in typical UK growing conditions.

What is anagallis?

Anagallis (pimpernel) is a genus of low-growing annuals and short-lived perennials grown for their small but vivid five-petalled flowers. Anagallis monelli (blue pimpernel) produces intense gentian-blue flowers and is a popular annual for containers and the front of borders. The native scarlet pimpernel (Anagallis arvensis) is a charming British wildflower. Anagallis flowers open in sunshine and close in shade and dull weather.

When should I sow anagallis?

Sow Anagallis monelli under glass from February to April at 16 to 18 degrees Celsius. It needs light to germinate so surface sow without covering the seed. Prick out carefully and grow on under glass before hardening off and planting outside after the last frost in May. Anagallis can also be direct sown in a sheltered position in May once the soil has warmed.

Why won't my anagallis flowers open?

Anagallis flowers open in full sun and close in shade, dull weather, and at night. This is entirely normal behaviour. If the flowers remain closed during the day, the position is too shaded or the weather is too overcast. For the best floral display from anagallis, grow it in the sunniest, most sheltered position available.