Red leaves on geraniums often signal an underlying issue, though sometimes it’s a natural reaction. Understanding the reasons for this discoloration is the first step to restoring your plant’s green vibrancy. This article clarifies why geranium leaves turn red and provides methods to resolve these concerns.
Common Causes of Red Geranium Leaves
Red or purplish discoloration on geranium leaves often signals environmental stress or nutrient imbalances.
Cold temperatures induce red coloration, especially below 50°F (10°C). This stress response triggers anthocyanin pigment production, appearing red or purplish along leaf edges and veins.
Phosphorus deficiency can cause red or purplish leaves, especially on older, lower foliage. This nutrient is important for energy transfer and root development. Its scarcity leads to stunted growth and a deep red or purple tint.
Magnesium deficiency often appears as interveinal chlorosis, with yellowing between green veins. Older leaves may also develop reddish or purplish tints, sometimes progressing to necrosis. Magnesium is a central component of chlorophyll; its absence impairs photosynthesis, causing these symptoms.
Excessive sun exposure can cause geranium leaves to develop a reddish or bronzed appearance. This coloration is a protective mechanism, as the plant produces anthocyanins to shield its chlorophyll from photodamage. Direct, intense afternoon sun makes leaves susceptible.
Water stress, from insufficient or excessive moisture, can also lead to red leaves. Underwatering causes leaves to turn red, brown, and crispy, often with wilting. Conversely, overwatering results in red, mushy leaves, often with yellowing, due to root damage in waterlogged soil.
An imbalance in soil pH can indirectly contribute to red geranium leaves by affecting nutrient availability. If the soil is too acidic (below pH 6.0) or too alkaline (above pH 7.5), nutrients like phosphorus and magnesium can become locked up. Even if present, the plant cannot absorb them efficiently, leading to deficiency symptoms like reddish discoloration.
How to Remedy Red Geranium Leaves
Addressing the cause of red geranium leaves involves specific actions tailored to the identified problem. Prompt intervention can help restore your plant’s health and vibrant green foliage.
When cold stress is the culprit, protecting geraniums from low temperatures is the primary remedy. Move potted plants indoors or to a sheltered location, like a garage or porch, when nighttime temperatures drop below 50°F (10°C). For in-ground plants, cover them with a frost cloth or old blanket during cold snaps.
Correcting nutrient deficiencies requires specific supplementation. For phosphorus deficiency, apply a balanced fertilizer (e.g., 5-10-5 or 10-20-10) or a phosphorus-rich amendment like bone meal. Incorporate bone meal into the soil (about one tablespoon per gallon of potting mix) or sprinkle around in-ground plants and water thoroughly.
Magnesium deficiency can be treated with Epsom salts (magnesium sulfate). Dissolve one tablespoon of Epsom salts in one gallon of water to create a solution. Apply this as a foliar spray directly onto leaves or as a soil drench every 2-4 weeks until symptoms improve.
Providing appropriate light levels helps if excessive sun exposure causes redness. Move potted geraniums to partial shade, especially during intense afternoon hours. For in-ground plants, provide temporary shade with a shade cloth or by planting taller, sun-tolerant plants nearby.
Correcting watering practices addresses water stress. Before watering, check soil moisture by inserting a finger two inches deep; water only when the topsoil feels dry. Water thoroughly until it drains from the pot bottom. Always ensure pots have adequate drainage holes to prevent waterlogging.
Adjusting soil pH can resolve nutrient lock-up issues. First, conduct a soil test to determine the exact pH level. If the soil is too acidic (below pH 6.0), add agricultural lime to raise the pH gradually. For alkaline soil (above pH 7.0), incorporate elemental sulfur or use an acidic fertilizer to lower the pH, making nutrients more available.
Preventing Future Redness
Proactive care and consistent attention maintain healthy geraniums and prevent red leaves. Establishing a routine that addresses their fundamental needs can keep your plants thriving.
Implement a consistent care routine, including regular monitoring for early stress signs. Maintain a consistent watering schedule, adjusting frequency based on weather and plant needs, ensuring evenly moist but not waterlogged soil. A regular feeding schedule with a balanced fertilizer provides nutrients for robust growth.
Ensure your geraniums are planted in the right location, considering their specific light and temperature requirements. Geraniums prefer at least six hours of daily sunlight but benefit from afternoon shade in hotter climates. Choosing a spot with good air circulation also contributes to overall plant health.
Adjust care practices according to changing seasons to meet the plant’s evolving needs. During cooler months, reduce watering frequency to prevent root rot. In contrast, during hot summer spells, increase watering and consider providing additional shade to protect foliage from intense sun.
Conduct regular inspections of your geraniums, examining both the top and underside of leaves and the soil condition. Early detection of issues like nutrient deficiencies or improper watering signs allows for timely intervention.