Why Are My Strawflower Leaves Curling?
Xerochrysum bracteatum, the strawflower or everlasting flower (formerly Helichrysum bracteatum), is a half-hardy annual from Australia grown for its papery, daisy-like flowers in brilliant shades of red, orange, yellow, pink, and white. It is equally valued as a fresh cut flower and as a dried flower, with the papery bracts retaining their colour and shape for months after drying. The grey-green, lance-shaped leaves are covered in fine hairs and the whole plant has a dry, slightly rough texture typical of its arid habitat. When the leaves curl or the plant looks stressed, these are the most common causes.
Aphid infestation
Aphids are the most common pest on xerochrysum. They colonise the shoot tips and the undersides of the grey-green, hairy leaves, where their feeding causes the leaves to curl, pucker, and distort. The hairy surface of the leaves makes it slightly harder for aphids to move but does not prevent colonisation. Green aphids and cotton aphid are both found on strawflower. Heavy infestations on the shoot tips can distort the developing flower buds and reduce the number and quality of flowers produced.
What to do
- Check the shoot tips and the undersides of young leaves regularly for aphid colonies.
- Spray with insecticidal soap every four to five days for two to three weeks, covering the undersides of the hairy leaves thoroughly.
- Avoid high-nitrogen fertilisers that produce soft, lush growth especially attractive to aphids. Xerochrysum grows best in lean, poor conditions anyway.
Overwatering and root rot
Overwatering and root rot are more serious problems for xerochrysum than drought. As a plant of dry Australian conditions, strawflower has evolved for excellent drainage and is highly susceptible to root and crown rot in wet soils. In persistently waterlogged compost or in heavy clay, the roots deteriorate rapidly and the plant declines: the grey-green leaves yellow and curl, the stems become soft at the base, and the whole plant wilts despite wet soil. This is one of the most common causes of strawflower failure in UK gardens and is particularly likely in containers or in a typical wet UK summer.
What to do
- Plant xerochrysum in very well-drained, even poor and gritty soil. It thrives in conditions too dry for most annuals.
- On heavy clay, grow strawflower in raised beds or containers of gritty, free-draining compost.
- Water only when the top 3 to 4 cm of compost feel dry. Never keep the compost consistently moist.
- Ensure containers have large drainage holes and do not use saucers under strawflower pots.
Drought stress
While xerochrysum is drought tolerant relative to most annuals, even this Australian native will show stress during prolonged dry spells, particularly in containers where the root system has limited water access. The grey-green leaves curl inward at the margins and the plant produces fewer, smaller flowers. Drought tolerance is not the same as drought immunity, and consistent moisture at a moderate level produces significantly better plants than alternating between wet and bone-dry conditions.
What to do
- Water xerochrysum when the compost or soil feels dry 3 to 4 cm down. In the ground during a normal UK summer, watering is rarely necessary for established plants.
- In containers, check more frequently in hot weather and water before the plant shows stress symptoms.
- The key is consistency: moderate, regular watering on a demand basis rather than frequent light watering or infrequent heavy soaking.
Powdery mildew
Powdery mildew occasionally affects xerochrysum in warm, dry conditions or when plants are crowded with poor air circulation. The grey-green leaves develop a white powdery coating and the affected areas curl and look bleached. Because the leaves are already grey-green and covered in fine hairs, early powdery mildew can be easy to miss until it has become well established.
What to do
- Space xerochrysum plants at least 30 cm apart to ensure good air circulation. Overcrowding is the most common predisposing factor.
- Remove and bin affected leaves and stems. Spray remaining healthy growth with a sulphur-based fungicide or potassium bicarbonate solution.
- Ensure adequate (but not excessive) watering: drought-stressed plants are significantly more susceptible to powdery mildew.
Cold damage
Xerochrysum is half-hardy and should not be planted outside until after the last frost. Young plants exposed to temperatures below 5 degrees Celsius develop pale, translucent patches on the hairy leaves, which curl, brown at the edges, and deteriorate. Cold damage is most likely when plants are put out too early or when a late cold snap follows an early warm period. Hardy annual sowing direct in April is more resilient to cold than tender transplants but can still be damaged by a hard late frost.
What to do
- Plant out after late May when nighttime temperatures are reliably above 8 degrees Celsius.
- Harden off transplants thoroughly for at least two weeks before planting out.
- Cover with fleece if a late cold snap is forecast. Remove cold-damaged growth once temperatures recover.
Frequently asked questions
Why are my strawflower leaves curling?
Strawflower leaves curl most often from aphid infestation or overwatering. Aphids cluster on the shoot tips and the undersides of the grey-green leaves, causing them to curl and distort. Overwatering in poorly draining soil causes the roots to rot and the leaves to yellow and curl, as strawflower is a plant of dry, well-drained conditions that is highly sensitive to wet roots.
Why are my xerochrysum leaves turning grey and curling?
The leaves of xerochrysum are naturally grey-green and covered in fine hairs, which is normal. If the leaves are curling and the grey colouring seems more pronounced or dull, the plant may be under water stress, pest pressure, or powdery mildew. Drought causes the leaves to curl and look dull. Check the undersides for aphids and examine the leaf surface for the white powdery coating of mildew.
How do I dry strawflowers successfully?
Cut strawflower stems when the flowers are about half to three quarters open: the flowers continue opening after cutting and the papery bracts are most vibrant before the flowers are fully mature. Remove the leaves and hang upside down in small bunches in a warm, dry, ventilated space. Drying takes one to two weeks. The papery flowers retain their colour and shape for months or years when dry.
When should I sow xerochrysum?
Sow strawflower under glass from March to April at 18 to 20 degrees Celsius. Surface-sow the fine seeds and do not cover, as they need light to germinate. Germination takes seven to fourteen days. Plant out after the last frost in late May or June in a sunny, well-drained position. Alternatively, sow direct outdoors from mid-April after the last hard frosts.