Why Are My Lunaria Leaves Curling?

Aphid infestation

Aphids are the most common pest on lunaria. Both the cabbage aphid (a grey-green waxy species) and black bean aphid target honesty, clustering on the shoot tips and the undersides of the large, slightly hairy leaves. Aphid feeding causes the leaves to curl, pucker, and distort. Because lunaria grows as a rosette in its first year and the leaves are large and numerous, aphid colonies can build up significantly in the heart of the plant before becoming visible. In the second year, aphids frequently colonise the developing flower and seed pod stems.

What to do

• Check the shoot tips and the undersides of young leaves regularly, and part the rosette to inspect the inner leaves and stems where aphid colonies often shelter.
• Spray with insecticidal soap every four to five days for two to three weeks, ensuring good coverage of the leaf undersides.
• A jet of water helps dislodge aphids from the large, robust leaves before chemical treatment.
• Natural predators including ladybirds and hoverflies provide good biological control as the season advances.

Clubroot

Clubroot is a serious soil-borne disease caused by the organism Plasmodiophora brassicae that affects all members of the brassica family, including lunaria. Infected plants produce swollen, distorted roots that can no longer function properly, causing the leaves to wilt, yellow, and curl even when the soil is moist. Above ground, affected plants look stunted and progressively more sickly. Once clubroot is established in soil it persists for many years: there is no chemical treatment and the only management strategy is prevention and rotation.

What to do

• If you suspect clubroot, pull one plant and examine the roots: large, irregular, distorted swellings on the roots are the definitive sign.
• Remove and bin all infected plants. Do not compost them.
• Do not grow lunaria or any other brassica family plant in the same soil for at least seven years. The spores persist for decades in severe cases.
• Lime the soil to raise pH to 7 or above: clubroot is much less severe in alkaline soil. Apply lime in autumn before sowing or planting brassicas.
• Raise plants in modules of sterilised compost and plant out with a minimal root disturbance to reduce exposure to soil-borne spores.

Flea beetle damage

Flea beetles are a very common pest on all brassica family plants in spring and summer. The small, shiny, jumping beetles chew numerous small, round holes in the leaves, causing the damaged tissue to curl and shrivel. Young lunaria seedlings and the first-year rosette leaves are most vulnerable. Heavy flea beetle pressure on small seedlings can severely check growth or kill plants, while established rosettes tolerate moderate damage without lasting harm.

What to do

• Cover young seedlings with fine insect mesh immediately after germination to exclude flea beetles during the most vulnerable stage.
• Water seedlings regularly: flea beetle damage is significantly worse on plants under drought stress.
• Once the first-year rosette is well established with large, tough leaves, flea beetle damage becomes less significant and plants usually outgrow the problem without intervention.

Drought stress

Lunaria is reasonably tolerant of dry conditions once established in the ground but the large leaves wilt and curl in prolonged dry spells, particularly for young plants in their first year of growth. First-year seedlings sown in summer are most vulnerable during dry, hot periods. Drought stress makes the large leaves look limp and reduces the vigour of the plant going into winter.

What to do

• Water newly sown and young lunaria plants regularly during dry spells in summer and autumn during the first year of growth.
• Established second-year plants are more drought tolerant but benefit from watering during very dry periods in spring when they are actively flowering and setting seed.
• Mulch around plants to retain soil moisture and suppress weeds through dry periods.

Downy mildew

Downy mildew occasionally affects lunaria, particularly in wet, cool spring conditions or when plants are overcrowded. The upper surface of the large leaves develops yellow or pale patches and the affected areas curl slightly. On the undersides, a grey or purple-tinged downy growth is visible in wet conditions. It is distinct from powdery mildew, which produces a white surface coating on dry foliage. Downy mildew is most damaging on first-year plants in wet autumns.

What to do

• Improve air circulation by thinning plants to at least 30 cm apart.
• Remove and bin affected leaves. Avoid overhead watering which promotes the spread of downy mildew spores.
• Spray with a copper-based fungicide as directed on the label at the first sign of infection.

Frequently asked questions

Why are my lunaria leaves curling?

Lunaria leaves curl most often from aphid infestation or clubroot disease. Aphids target the shoot tips and young leaves, causing them to curl and distort. Clubroot, a soil-borne disease affecting all members of the brassica family including lunaria, causes the leaves to wilt, yellow, and curl as the infected roots swell and deteriorate.

Why are my honesty leaves turning yellow and curling?

Yellow curling leaves on lunaria suggest clubroot infection, nutrient deficiency, or natural senescence of the lower leaves as the biennial plant matures and sets seed in its second year. Pull a plant and examine the roots: swollen, distorted roots indicate clubroot. Yellow lower leaves on otherwise healthy plants in the second year of growth are usually normal ageing.

When should I sow lunaria?

Lunaria annua is a biennial, sown from May to July in its first year to produce a rosette that overwinters and flowers the following spring before setting its distinctive silvery seed pods. Seed sown in late spring to early summer is most reliable for a good display the following year.

Does lunaria self-seed?

Yes, lunaria self-seeds freely once established. The self-sown seedlings emerge in summer and autumn and follow the same biennial cycle, flowering the following spring. In most gardens lunaria perpetuates itself indefinitely without any further sowing. Thin the self-sown seedlings in autumn to 30 cm apart for the best flowering display.