What Causes Black Spots or Dead Areas on the Ends of Leaves of House Plants?

Lack of Humidity

• Dry indoor air deprives houseplants of the moisture that is contained outdoors. The moisture level in the air affects how much water the plant loses. If the air is too dry, the leaves' edges turn brown. To solve the problem, mist the houseplant with clean water early in the morning. Another option is to set the houseplant's container on a tray of pebbles and pour water over the pebbles. As the water evaporates, it creates a curtain of humidity around the houseplant and supplying the leaves with extra moisture. Also, avoid placing the houseplant near drying air vents.

Salt Buildup

• Salt buildup occurs in houseplants for several reasons, including watering with tap water, fertilizing and certain potting mixes. Over time, salt accumulates at the surface to create a white crusty layer that can lead to dead-edged leaves. Reduce salt buildup by watering the houseplant with rainwater, not allowing it to sit in a tray of water, not over-fertilizing and occasionally re-potting.

Improper Watering

• One of the most common reasons houseplants suffer problems is due to improper watering. The houseplant's leaves turn brown around the edges when they do not receive ample water. Although water needs vary between plant species, allow the soil to dry out between each watering, and water thoroughly until the water pours out of the drainage holes. Don't allow the houseplant to sit in a tray of water because this leads to fungal diseases.

Leaf Spot

• Black or brown spots on a houseplant's leaves indicate a fungal infection. Fungi thrive in moist conditions and harbor on dead plant debris. Remove infected leaves and debris and implement proper watering methods. Apply a Bordeaux mix fungicide, made of copper sulfate and hydrated lime.

Sooty Mold

• Black patches of mold on the leaves or stems indicate the houseplant is growing sooty mold, which wipes off the plant easily with warm water or rubbing alcohol. Sooty mold grows on the honeydew excreted from certain sap-sucking insects like aphids, mealybugs and whiteflies. To control sooty mold, control the houseplant pests. Spray an insecticidal soap on the houseplant out of direct sunlight. Commercial insecticidal soaps are available, but homemade versions are effective also. Make a homemade insecticidal soap by filling a spray bottle with water and adding a teaspoon of mild dish soap. Mix thoroughly and spray the houseplant, including the leaves' undersides.