Geum, commonly called avens, is a rewarding perennial with cheerful flowers in warm shades of orange, red, and yellow. It forms neat rosettes of scalloped leaves that should stay flat and vibrant through most of the season. When those leaves start to curl, cup, or pucker, something is off. The good news is that the main causes are identifiable and reversible once you know what to look for.
1. Powdery mildew
Powdery mildew is a very common problem on geum, particularly in gardens where plants are crowded or in positions with restricted airflow. The fungal pathogens responsible, including Sphaerotheca and Erysiphe species, colonize leaf surfaces and cause leaves to pucker, curl upward, and develop a distinctive white or grey dusty coating. Symptoms typically appear in mid to late summer when warm days combine with cool, humid nights.
What to look for
- White or grey powdery patches on upper leaf surfaces
- Leaves curling or puckering upward around infected areas
- New growth distorted or stunted in severe cases
- Symptoms spreading from shaded or crowded sections outward
- Worse after periods of warm days followed by cool, damp nights
How to fix it
Remove and dispose of (do not compost) heavily infected leaves. Open up the plant by dividing congested clumps and spacing plants at least 30 cm apart. Apply a potassium bicarbonate or sulfur-based fungicide every seven to ten days during active infection. Avoid overhead watering, which spreads spores and creates the humid surface conditions the pathogen needs. After the first flowering flush, cut geum back hard to stimulate fresh, mildew-free growth.
2. Aphids
Aphids target the tender new foliage at geum's crown and stem tips, feeding in colonies that cause leaves to curl tightly around them. The curling is a physical response to the feeding: as aphids drain sap from young tissue, the leaf loses structural integrity and distorts. A mat of curled leaves in the center of a rosette is a classic sign of a well-established aphid colony hidden inside.
What to look for
- Tightly curled or folded leaves at the center of the rosette
- Pale green, black, or woolly white insects inside the curled foliage
- Sticky honeydew on leaves and surrounding surfaces
- Ants foraging up and down stems
- Sooty mold on honeydew deposits in severe infestations
How to fix it
Use a strong jet of water to wash aphids off the plant, paying particular attention to the centers of rosettes. Follow up with insecticidal soap or neem oil, repeating every three to five days until the colony is eliminated. Encourage beneficial insects such as lacewings and hoverflies by planting companion flowers nearby. Avoid excessive nitrogen fertilization, which produces the lush sappy growth aphids prefer.
3. Spider mites
In hot, dry summers, two-spotted spider mites (Tetranychus urticae) can colonize geum rapidly, causing a fine stippled or bronzed appearance on leaf surfaces alongside curling and yellowing. Mites are so small that populations explode before gardeners notice them, and by the time webbing is visible the infestation is well established.
What to look for
- Fine bronze or silver stippling across leaf surfaces
- Leaves curling and yellowing, particularly on the underside
- Delicate webbing connecting leaves and stems in heavy infestations
- Tiny moving dots visible under a magnifying glass on leaf undersides
- Symptoms accelerating during hot, dry spells
How to fix it
Mist foliage regularly to raise humidity and make conditions less favorable for mites. Rinse plants with water every two to three days. Apply neem oil or insecticidal soap weekly for three to four weeks. Ensure geum is not drought-stressed, as water-stressed plants are far more vulnerable to mite damage.
4. Drought stress
Geum performs best in consistently moist but well-drained soil. In prolonged dry spells, particularly on light sandy soils or in containers, the plant's leaves roll inward to reduce water loss through transpiration. This moisture-conserving curl is the plant's survival mechanism rather than a disease or pest, and it reverses quickly once water is available.
What to look for
- Leaves rolling longitudinally, edges curling up and inward
- Soil dry well below the surface when probed
- Leaves recovering quickly after thorough watering
- Whole plant wilting slightly in the heat of the day
- Symptoms most pronounced on exposed or south-facing sites
How to fix it
Water deeply and consistently rather than shallowly and frequently, so moisture reaches the root zone. Apply a 5 cm layer of organic mulch around the base of the plant to retain moisture and reduce surface temperature. In very exposed or free-draining positions, consider dividing and relocating geum to a spot with partial afternoon shade and better moisture retention.
5. Root rot
Despite needing consistent moisture, geum does not tolerate waterlogged conditions. In heavy clay soils or poorly drained pots, roots can suffocate and rot, which paradoxically causes the above-ground plant to show drought-like symptoms including leaf curl and wilting. Phytophthora and Pythium pathogens are the usual agents of rot in geum.
What to look for
- Leaves curling and yellowing despite soil feeling wet
- Plant collapsing or failing to perk up after watering
- Dark, slimy, or foul-smelling roots when the crown is lifted
- Crown tissue soft or discolored at or below soil level
- Symptoms worsening through winter in wet, cold soils
How to fix it
Lift the plant and cut away rotted root and crown tissue with sterile tools. Dust cut surfaces with powdered sulfur. Replant in a raised bed, a grit-amended border, or a pot with excellent drainage. Avoid heavy mulching directly against the crown, which holds moisture against the stem base and promotes rot.
6. Rust
Rust fungi, including Phragmidium species, occasionally attack geum, producing characteristic orange or brown pustules on leaf undersides and upper surface discoloration above them. Infected leaf tissue may distort and curl as the fungus disrupts normal cell function. Rust spreads rapidly by windborne spores and prefers cool, moist conditions in spring and autumn.
What to look for
- Orange, rust-colored pustules on the undersides of leaves
- Yellow or pale spots on the corresponding upper leaf surface
- Affected leaves curling or puckering around infected areas
- Spores rubbing off as orange powder on fingers
- Infection spreading from lower leaves upward
How to fix it
Remove and bin all infected leaves at first sign of rust. Apply a copper-based fungicide or a systemic fungicide containing tebuconazole every seven to fourteen days during active infection. Avoid overhead watering and keep foliage as dry as possible. Clear away plant debris at the end of the season, as rust spores overwinter on dead tissue.
Quick diagnosis checklist
| Symptom | Most likely cause | First action |
|---|---|---|
| White powder, upward curl, warm humid nights | Powdery mildew | Remove leaves, improve airflow, fungicide |
| Curled rosette center, sticky residue, ants | Aphids | Water blast, insecticidal soap |
| Bronze stippling, webbing in hot dry weather | Spider mites | Rinse foliage, neem oil weekly |
| Inward roll, dry soil, recovers after watering | Drought stress | Deep water, mulch, check drainage |
| Curl with wet soil, mushy crown, plant collapsing | Root rot | Lift, trim roots, improve drainage |
| Orange pustules under leaf, yellow spots above | Rust | Remove leaves, copper fungicide |
Frequently asked questions
Why are my geum leaves curling?
Geum leaves curl most commonly because of aphid colonies on new growth, powdery mildew infection in warm humid conditions, or drought stress during dry spells. Inspect shoot tips for insects, check for white powdery patches, and feel the soil to narrow down the cause.
Does powdery mildew cause geum leaves to curl?
Yes. Powdery mildew caused by Sphaerotheca and Erysiphe species affects geum in warm days with cool, humid nights. Infected leaves develop a white dusty coating and often curl or pucker upward. Remove affected foliage, improve air circulation, and apply a fungicide if the outbreak is widespread.
Can geum leaves curl from underwatering?
Yes. Geum needs consistent moisture during the growing season, especially in sunny or exposed positions. During dry spells the leaves roll inward to reduce water loss. Water deeply at the base, apply mulch, and avoid letting the soil dry out completely between waterings.
What causes geum leaves to curl and turn bronze?
Bronze or copper-colored curling on geum is often caused by spider mites, which thrive in hot, dry summer conditions and create fine stippling across leaf surfaces. Rinse the foliage and apply neem oil or insecticidal soap weekly to bring them under control.
Should I cut back geum when the leaves are curling?
Light cutting back after the first flush of flowers is a good practice that removes diseased or pest-damaged foliage and stimulates fresh growth. Avoid hard cutting if geum is already stressed by drought or root problems, as the plant needs its remaining foliage to recover.