The African Milk Tree (Euphorbia trigona) is a popular succulent known for its distinctive upright form. Though generally low-maintenance, browning stems or leaves are a common concern. This discoloration signals underlying health problems, and understanding its causes is key to resolution.
Common Reasons Your African Milk Tree is Turning Brown
Overwatering is a frequent cause of browning, leading to root rot. Consistently wet soil deprives roots of oxygen, promoting fungal growth and causing them to become mushy, black, or dark brown. This often manifests as soft stems with black or brown spots. Affected leaves may also turn yellow, swell, or become translucent before browning and falling off.
Insufficient water can also cause browning. When underwatered, stems and leaves may shrivel, dry out, and become crispy or brittle. This desiccation often begins at the tips or edges of the foliage. Leaves may appear flattened or pale green before turning brown and dropping.
Inadequate light can weaken the African Milk Tree, leading to stunted growth and browning. While these succulents tolerate some shade, prolonged low-light conditions stress the plant. Conversely, excessive direct sunlight can cause sunburn, appearing as bleached or reddish-brown spots that become dry and crispy on stems and leaves.
Temperature extremes also stress these plants, leading to browning. Sudden drops in temperature, cold drafts, or exposure below 50°F (10°C) can cause damage, resulting in yellowed foliage and browning on branch ends. Excessive heat can also contribute to dehydration and browning.
Pests like mealybugs and spider mites can weaken the plant, leading to discoloration and browning. Mealybugs appear as cotton-like clusters, while spider mites may leave tiny webs or cause a dusty appearance. Fungal issues, often linked to overwatering, can also cause black or brown spots on stems and leaves.
Nutrient imbalances or poor soil conditions can contribute to browning. Compacted soil hinders proper root function and nutrient absorption, leading to plant stress. Soil deficient in essential nutrients can also impair health, causing general decline and discoloration.
Reviving a Browning African Milk Tree
For plants affected by overwatering and root rot, unpot the plant to inspect the root system. Trim away any dark brown, black, soft, or mushy roots with sterilized tools. Allow the roots to air dry for several hours or a day to callus before repotting in fresh, well-draining succulent or cactus mix.
If underwatering caused browning, rehydrate the plant. Thoroughly soak the soil until water drains from the pot’s bottom. Bottom watering, where the pot sits in a tray of water, can also be effective. Gradually reintroduce water.
Address light issues by relocating the plant. If insufficient light is the problem, move it to a spot receiving bright, indirect sunlight. If browning is due to sunburn, transition the plant to a location with bright, indirect light or filtered sun. Gradually acclimate the plant to new light conditions.
For temperature-stressed plants, move them away from cold drafts, air conditioning vents, or extreme heat. Maintain stable indoor temperatures, ideally between 65°F and 85°F (18°C to 29°C). If exposed to cold, trim back any brown, damaged sections.
For pest infestation, treat promptly. Mealybugs and spider mites can be treated with horticultural oil, neem oil, or insecticidal soap. A diluted solution of mild dish soap and water or rubbing alcohol with a cotton swab can also remove visible pests. Isolate the affected plant.
When nutrient imbalance or poor soil is the issue, repot with a fresh, appropriate soil mix. Use a well-draining succulent or cactus mix, possibly amended with perlite or coarse sand for aeration. Fertilize with a balanced, diluted fertilizer during the active growing season (spring and summer).
Preventing Browning: Long-Term Care Tips
A proper watering schedule prevents browning and maintains African Milk Tree health. These drought-tolerant succulents prefer their soil to dry out completely between waterings. Use a “soak and dry” method, thoroughly watering and then allowing the soil to dry. Adjust frequency seasonally, reducing it during fall and winter dormancy.
Provide optimal light conditions to prevent browning. African Milk Trees thrive in bright, indirect light, tolerating some direct morning or late afternoon sun. A south or west-facing window indoors is often ideal. Shield them from intense midday sun to prevent scorching.
Use an ideal soil mix to prevent waterlogging and root issues. A well-draining succulent or cactus mix provides necessary aeration and prevents moisture retention. Incorporating perlite, pumice, or coarse sand can further enhance drainage. A pot with drainage holes is also important for excess water to escape.
Maintain stable temperatures and appropriate humidity levels for plant health. African Milk Trees prefer warm environments, typically between 65°F and 85°F (18°C to 29°C). Protect them from cold drafts, sudden temperature drops, and excessive humidity to avoid stress-induced browning.
Fertilize cautiously. During the active growing season (spring and summer), apply a balanced, diluted liquid fertilizer monthly. Avoid fertilizing during fall and winter dormancy to prevent nutrient buildup.
Regularly monitor for pests and diseases. Inspect the plant frequently for signs of mealybugs, spider mites, or unusual spots. Promptly address any identified issues.