Brown Tips on a Cast Iron Plant

Fluoride Toxicity

• Cast iron plants grown indoors are often affected by fluoride in the water, which causes the leaf tips to take on a brown, scorched appearance. Eventually, the damaged area extends further into the leaf. Letting the water stand for a few days before watering causes much of the fluoride to evaporate. You can also water the plant with rainwater or bottled water.

Excessive Fertilization

• Many indoor gardeners kill their plants with kindness by applying too much fertilizer, but cast iron plant has low nutritional needs, and too many nutrients may cause brown leaf tips. Provide a balanced, water-soluble fertilizer once every month during spring and summer, then withhold fertilizer during fall and winter because the plant requires a period of rest and low growth. If you forget to fertilize, the plant won't be harmed. Mix the fertilizer at a rate of 1 tablespoon of fertilizer per gallon of water for outdoor plants, and only 1/2 teaspoon of fertilizer per gallon of water for indoor plants. Always water immediately after feeding the plant.

Excessive Dryness

• Excessively dry soil is a common problem that may result in brown leaf tips. While cast iron plant survives even under duress, the plant prefers regular watering. Water an indoor cast iron plant deeply whenever the top 1 inch of potting soil feels dry. Allow the pot to drain thoroughly and never let it stand in water. Watering an outdoor plant is similar. Wet the soil to a depth of about 6 inches, then let the soil dry until the top 1 inch feels dry. The soil should be neither soggy nor bone dry.

Soluble Salt Buildup

• Indoor cast iron plants are susceptible to damage by a buildup of soluble salts, which may cause the leaf tips to turn brown. The buildup of salt is caused by overwatering, especially if the plant is watered from the bottom. Occasional watering from the top helps wash salt through the drainage hole and prevents buildup. If you notice an accumulation of salt on the surface of the soil, scrape off the white soil and replace it with fresh potting mix. Other signs of salt buildup include dropping of leaves, wilting and stunted growth.