Browning daylily leaves are common, often prompting concern. While some browning is natural, other instances signal underlying issues. Understanding the distinction helps diagnose the problem and maintain plant health.
Natural Browning
Daylily foliage naturally browns and dies back as part of its normal growth, especially after flowering or as it prepares for dormancy. This natural browning usually affects older, lower leaves first and progresses gradually. If only a few older leaves brown while the rest of the plant appears healthy and new growth emerges, it is likely a natural process.
Watering Problems
Watering issues frequently cause daylily leaves to brown, encompassing both too little and too much water. Underwatering leads to drought stress, where leaves become crispy, dry, and brown, often accompanied by wilting. Daylilies can tolerate some dry periods once established, but consistent moisture is beneficial, especially during active growth and blooming. Provide regular, deep watering to thoroughly saturate the soil.
Conversely, overwatering can be equally damaging, depriving roots of oxygen and leading to root rot. Symptoms include soggy, dark brown or black leaves, a mushy crown or roots, and general yellowing before browning. Daylilies prefer well-drained soil and dislike consistently wet conditions. To prevent overwatering, allow the soil to dry slightly between waterings and ensure adequate drainage.
Pests and Diseases
Daylilies can experience browning due to various pests and diseases, each presenting distinct symptoms.
Pests
Spider mites, tiny arachnids thriving in hot, dry conditions, pierce plant tissue to suck sap. This causes pale speckling, then bronze and brown leaves. Fine webbing may be visible on undersides. Control with forceful water sprays or insecticidal soap for severe infestations.
Thrips are small, fast-moving insects that feed on leaves and flower buds, causing silvery streaks, distorted growth, and brown streaking. Heavy infestations stunt leaves and prevent buds from opening. Remove dead growth and debris to help prevent them; insecticidal soap or strong water sprays can manage populations.
Aphids, soft-bodied insects, feed in colonies and suck plant sap, resulting in yellowing or browning leaves, distorted new growth, and sticky “honeydew.” Ladybugs and lacewings are natural predators; insecticidal soap sprays are effective for control.
Diseases
Fungal diseases like Daylily Rust and Leaf Streak also cause browning. Daylily Rust manifests as small, yellow to brown streaks and bright yellow spots on the leaf surface, with orange pustules on the undersides. Infected leaves often yellow, turn necrotic, and dry. Remove infected foliage and improve air circulation for management.
Leaf Streak causes elongated yellow streaks along the leaf mid-vein, followed by reddish-brown spots or browning progressing from the leaf tip downward. This disease can lead to leaves withering and dying. Avoid overhead irrigation and remove dead foliage in the fall to help prevent its spread.
Environmental Stress and Chemical Damage
Environmental factors and chemical damage can cause daylily leaves to brown.
Environmental Stress
Extreme temperatures can cause browning. Heat stress often results in browning edges and wilting during prolonged hot periods; providing adequate water helps. Cold damage, such as frost, can cause leaves to brown and die back, particularly in evergreen varieties. Cover plants during unexpected late frosts for protection.
Transplant shock, occurring after moving a daylily, can lead to temporary browning as the plant adjusts. Proper transplanting techniques, including careful handling of roots and consistent watering, aid recovery.
Chemical Damage
Improper application of herbicides or fertilizers can cause browning. Herbicide drift from nearby spraying can result in uniform browning or scorched appearances. Fertilizer burn, often due to over-fertilization or direct contact with foliage, can also cause a scorched look. To prevent this, always follow product label directions carefully. Watering thoroughly after applying granular fertilizer helps reduce leaf burn risk.
Ongoing Care and Prevention
Maintaining healthy daylilies through consistent care practices can prevent many browning issues.
- Proper planting depth and spacing are foundational; the crown should be about one inch below the soil surface. Space daylilies 18 to 24 inches apart for good air circulation and growth.
- Daylilies prefer well-drained, fertile soil rich in organic matter. Amending soil with compost improves both drainage and water retention.
- Consistent watering is important, especially for newly planted daylilies and during dry spells, with about an inch of water per week. Water early in the day to allow foliage to dry, reducing disease risk.
- Fertilization should be balanced, using a slow-release formula like 10-10-10 or 5-10-10 in early spring. Avoid excessive nitrogen, which promotes leafy growth at the expense of blooms.
- Remove dead or diseased foliage promptly to help prevent the spread of pathogens.
- Ensure daylilies receive at least six hours of direct sunlight daily to promote robust growth and flowering.