Geraniums are popular plants known for their vibrant blooms. While generally resilient, they can encounter common pests that impact their health and appearance. Understanding these challenges helps gardeners protect their plants.
Common Geranium Pests
Aphids
Aphids are tiny, soft-bodied insects, often green, black, yellow, or brown. They typically cluster on new growth, including shoot tips, leaves, buds, and flowers, often on the undersides of leaves and at stem joints. Aphids feed by sucking sap, causing leaves to distort, curl, or yellow. Heavy infestations can stunt growth and damage flower buds. They also excrete sticky honeydew, which attracts ants and promotes black sooty mold.
Whiteflies
Whiteflies are small, winged insects resembling tiny white moths that fly out in a cloud when disturbed. They primarily feed on the undersides of leaves, laying eggs in clusters along veins. Whiteflies suck sap, causing yellowing leaves, stunted growth, and reduced plant vigor. Like aphids, they produce sticky honeydew, leading to sooty mold that can hinder photosynthesis.
Spider Mites
Spider mites are tiny arachnids, difficult to see without magnification, appearing as small moving dots. They are typically yellowish-green with two dark spots, or reddish-orange. These pests thrive in hot, dry conditions, feeding on the undersides of geranium leaves by sucking cell contents. Early damage includes fine pale mottling or stippling on upper leaf surfaces, progressing to leaves turning bronze, yellow, or reddish and dropping off. Severe infestations show fine silk webbing on the plant, especially around leaves and stems.
Mealybugs
Mealybugs are soft, oval insects covered in white, cottony, waxy material, often appearing as fuzzy clusters. They are frequently found in protected areas like stem joints, leaf axils, or between touching leaves and stems; some species can also infest roots. Mealybugs feed by sucking sap, which reduces plant vigor and leads to yellowing leaves, wilting, and stunted growth. Their feeding also results in sticky honeydew and waxy deposits, attracting sooty mold and reducing the plant’s aesthetic quality.
Preventing Geranium Pests
Maintaining proper cultural practices minimizes pest infestations. Adequate watering, appropriate light, and balanced fertilization ensure plant health and vigor, making geraniums less susceptible to pests.
Regular inspection allows for early pest detection before infestations become severe. Routinely check the undersides of leaves, stems, and new growth for any signs of insects or damage. Early identification enables quicker intervention, preventing widespread issues.
Good sanitation practices contribute to a pest-free environment. Remove dead leaves, plant debris, and weeds from around geraniums to eliminate hiding and breeding spots. Dispose of badly infested plants in the trash, not the compost pile, to break pest life cycles.
Quarantining new plants prevents pest spread to existing collections. Inspect new geraniums thoroughly for infestations and isolate them for a period. This practice reduces the risk of inadvertently bringing pests into your garden or home.
Good air circulation deters certain pests. Overcrowding creates humid, stagnant conditions that many pests favor. Proper spacing allows air movement, keeping foliage dry and less appealing to pests like spider mites and whiteflies.
Treating Geranium Pests
Non-Chemical Solutions
Manual removal is an effective initial step for minor infestations. Pick off larger pests like mealybugs by hand or with a cotton swab dipped in rubbing alcohol. For aphids and spider mites, a strong jet of water can dislodge them from plant surfaces, especially leaf undersides. This method, syringing, can be repeated every few days to control pest populations.
Insecticidal soap is a less harsh treatment for soft-bodied pests like aphids, whiteflies, spider mites, and mealybugs. These soaps suffocate insects on contact, requiring thorough coverage of all plant surfaces, including leaf undersides. Test the soap on a small plant area first, as some geranium varieties are sensitive. Apply in the early morning or late day to avoid leaf damage from strong sunlight.
Neem oil, a natural pesticide, disrupts pest life cycles and acts as a repellent. It is effective against aphids, whiteflies, spider mites, and mealybugs. Dilute neem oil according to product instructions and apply as a foliar spray, thoroughly coating both top and undersides of leaves. Apply in the early morning or late evening to prevent leaf burn and protect beneficial insects.
Chemical Solutions
For severe or persistent infestations, chemical solutions may be a last resort. Systemic insecticides, absorbed by the plant and ingested by feeding pests, are effective against sap-sucking insects like aphids. Synthetic pyrethrin pesticides (e.g., permethrin, cyfluthrin, bifenthrin) are another option, usable for various pests including caterpillars and whiteflies. Always read and follow product label directions carefully, taking safety precautions like wearing gloves. Avoid application in direct sunlight or hot temperatures to prevent plant damage and ensure user safety, and ensure the product is suitable for geraniums and the target pest.