Why Are My Limnanthes Leaves Curling?

Aphid infestation

Aphids are the most common pest problem on limnanthes. They cluster at the shoot tips and on the undersides of the feathery, finely divided leaves, causing the delicate foliage to curl, pucker, and distort. Because limnanthes produces a mass of fine stems and leaves, aphid colonies can build up in the interior of the plant before becoming visible. Green aphids are most common, though blackfly can also affect limnanthes, particularly in spring when the plants are at their most vigorous.

What to do

• Part the foliage and inspect the shoot tips and inner stems for aphid colonies.
• A jet of water directed through the plants dislodges aphids from the fine stems effectively.
• Spray with insecticidal soap every four to five days for two to three weeks. The open flowers are visited by many beneficial insects including hoverflies that eat aphids: spray in the evening to avoid harming pollinators.
• In the vegetable garden, limnanthes is widely used as a companion plant to attract hoverflies whose larvae eat aphids: a healthy limnanthes patch is often self-regulating once hoverfly populations build up.

Overwatering

Despite its common name suggesting a wet habitat, limnanthes is susceptible to root problems in persistently waterlogged soil. The slightly succulent stems and roots deteriorate in very wet conditions, causing the whole plant to collapse, yellow, and produce curling, wilting foliage even when the soil is saturated. This is most common in containers without drainage, in heavy clay soils, or in beds that have been heavily watered during a wet spring. It can be mistaken for drought stress at first glance.

What to do

• Plant limnanthes in well-drained soil. It thrives in ordinary garden soil and does not need a rich, water-retentive bed.
• In containers, use free-draining compost and ensure adequate drainage holes.
• Reduce watering during wet or cool periods. Limnanthes is reasonably self-sufficient in typical UK spring conditions and does not need frequent watering once established.

Drought stress

Although limnanthes is a spring annual that naturally grows in conditions of moderate moisture, it can suffer from drought stress during warm, dry spring and early summer periods. The fine leaves wilt and curl inward, and the flowers become smaller and shorter-lived. Drought stress is most likely in containers, in free-draining sandy soils, or during unusually warm, dry springs that arrive early. Once the season turns hot and dry, limnanthes naturally begins to decline anyway, so severe summer drought is less of a concern than spring dryness.

What to do

• Water limnanthes during dry spells in spring, particularly in the weeks leading up to and during peak flowering.
• In containers, water when the top 2 cm of compost feels dry. Check every day or two in warm weather.
• Mulch around border-grown plants to conserve soil moisture through dry periods.

Heat stress

Limnanthes is a cool-season annual that performs best in spring and declines naturally as temperatures rise in June and July. In unusually hot, sunny weather in late spring, or in very sheltered, south-facing positions that trap heat, the plants may become stressed prematurely: the leaves curl and yellow, the flowers become smaller, and the plant begins to set seed and decline earlier than expected. This is a natural response to warm conditions and not a disease or pest problem.

What to do

• Accept that limnanthes is a short-season plant in hot summers. Allow the plants to self-seed and remove the spent plants once they decline: the self-sown seedlings will emerge in autumn for the following year.
• In very sunny, sheltered positions, grow limnanthes in autumn and early spring to take advantage of cooler temperatures before summer heat arrives.
• Ensure consistent moisture during warm spells to extend the flowering period as long as possible.

Flea beetle damage

Flea beetles occasionally attack limnanthes in spring, particularly when the plants are young seedlings. The small, jumping beetles chew small, round holes in the fine leaves and shoot tips, which can cause the damaged leaves to curl and look ragged. The damage is usually most severe in dry, warm conditions and on plants growing in close proximity to brassicas, which are the preferred host of many flea beetle species. Heavy damage to seedlings can significantly weaken young plants.

What to do

• Cover young limnanthes seedlings with fine mesh or fleece in spring to exclude flea beetles during the vulnerable seedling stage.
• Water the seedlings regularly: flea beetle damage is more severe on dry, stressed plants than on well-watered ones.
• Once plants are established with several sets of leaves, they usually outgrow flea beetle pressure without further intervention.

Frequently asked questions

Why are my limnanthes leaves curling?

Limnanthes leaves curl most often from aphid infestation or overwatering. Aphids cluster on the shoot tips and undersides of the feathery leaves, causing them to curl and distort. Overwatering in heavy or poorly draining soil causes the roots to deteriorate and the fleshy-stemmed plant to collapse and curl, despite wet conditions.

Why has my limnanthes stopped flowering?

Limnanthes flowers prolifically in spring and early summer but fades as temperatures rise through June and July. It performs best in cool conditions and naturally declines as summer advances. Deadheading regularly extends the flowering period. For a second flush, allow some plants to self-seed and remove the spent plants: the self-sown seedlings will emerge in autumn and flower the following spring.

When should I sow limnanthes?

Limnanthes is best sown in autumn for spring flowering: the seeds germinate in cool, moist conditions and the small plants overwinter well in mild UK gardens. Spring sowing from March onwards is also successful and flowers by May or June. Sow direct where the plants are to grow, as they dislike root disturbance.

Does limnanthes attract bees?

Yes, limnanthes is an outstanding plant for bees, hoverflies, and other beneficial insects. The shallow, open flowers are easily accessible to pollinators of all types, and a patch in flower is invariably covered in insect visitors. It is one of the most effective annual companion plants for attracting beneficial insects to the vegetable garden.