Q: What causes some of my houseplants to develop ‘brown leaf tips’? How do I go about diagnosing the problem?
Gardeners’ urge to grow and nurture plants does not recede during the winter’s dark days. The conditions for maintaining plants inside during the winter are far from ideal. Houseplants that develop brown leaf tips are an early warning that these plants are stressed and need attention.
There are a variety of reasons why houseplants turn brown at their tips and other edges. Factors such as improper watering, low humidity, the wrong temperatures and light conditions, nutrient deficiencies, insect pests and diseases can influence the health of your plant.
First, it’s important to know basic characteristics of your plant or do some research to understand its growth habits and preferred growing conditions because different plants have differing requirements to thrive.
Let’s explore each of these factors, and learn how to diagnose and treat the problem. The top five reasons are described below, organized from most common to least common reasons for those brown leaf tips.
1. Water Requirements.
Too much, too little or inconsistent watering are major contributors to houseplant decline and can cause brown tips on houseplants.Overwatering, the most likely cause, decreases the amount of oxygen available for root growth and creates an environment susceptible to root diseases and rot. Underwatering results in leaf curling and death. Alternating between too much and too little water can also cause browning of leaf tips.
Diagnosis: The soil may be too wet or too dry. Overwatering leaves soil sticky and slimy and encourages fungal diseases; underwatering leaves it lighter in color and severe dryness results in cracked soil that pulls away from the pot edges. If the plant stem is soggy, droopy, or rotten, it’s getting too much water. If the leaves of the plant are yellow, curled and crispy, it’s underwatered. To test for the correct moisture level, stick your finger into the soil about two inches deep. If it feels dry, it’s time to water. Or, lift the plant, pot and all, to estimate its water content. A plant with dry potting medium will weigh much less than the plant which still has ample water in its potting medium. Another option is to use a moisture meter.
Treatment: Water houseplants until the soil is thoroughly saturated and excess water runs out the drainage holes. Make sure the pot drainage holes are not clogged and your plant doesn’t sit in water-filled saucers for more than an hour. Don’t assume that plants need watering on a set schedule or that all your houseplants are on the same schedule; test the moisture level before applying water. Suggestions on the kind of water to use are provided under the soil and fertilizer section below.
2. Humidity Level
Because of their tropical origins, most houseplants prefer slightly warm, humid environments. A relative humidity between 40 to 60 percent is ideal for most indoor plants. However, in winter, humidity in homes can fall to 10 percent, so increasing humidity may become necessary.
Diagnosis: When humidity levels are low, your plant will loose moisture through its leaves. Leaves may also start yellowing and curling down and drop off. Brown tips are often an indicator of low humidity, while browning along the edges indicate underwatering.
Treatment: To raise humidity, spray a water mist on plants periodically, group plants together, place them on a bed of moistened pebbles in a tray, put a humidifier in your plant room or add one to your heating system, add a fountain or aquarium to the space or keep plants in a terrarium or under a cloche (glass or plastic dome). Keep in mind that plants in high light situations may need more water and higher humidity.
3. Light and Temperature Conditions.
Ideal light and temperature conditions vary depending on the type of houseplant.
Houseplants with low light needs do well near a north window with no direct sun, or sunlight diffused through a lightweight curtain. Plants that require direct sunlight should be put in a south window and those with moderate light needs can be placed in western or eastern facing windows.
Most houseplants prefer temperatures ranging from 55°F to 70°F. In winter, the temperature near windows may be cooler than elsewhere in the house and this can damage the plants leaves. An overly hot, dry atmosphere from direct sunlight shortens the life of plants and may lead to brown leaf tips.
Diagnosis: If leaf discoloration is isolated to the side of the plant away from the light source or the plant seems to be reaching for the light, it’s probably receiving too little light. If the discoloration is close to the light source, it may be getting scorched. If the plant is getting too much heat, it will develop symptoms similar to those of underwatering. If the site is too cold for the plant, the brown leaf tips will be closer to the temperature source, usually a drafty window.
Treatment:To troubleshoot problems, check the plant’s light and temperature conditions and move it to a more suitable location. If a plant needs brighter light, move it to a window with direct sunlight or add grow lights or mirrors to reflect light. If a plant needs less light, move it into less light, or add a sheer curtain to filter light intensity. Dark walls and matte finishes can help absorb excess light. If the temperature is too cold, move to a warmer location. If the temperature is too hot, move to a cooler site. Remember not to put plants at windows that have hot air registers or radiators directly below them.
4. Salt Buildup, Fertilizer and Nutrients.
Fertilizers are salts and houseplants can develop brown leaf tips, if too much fertilizer is applied. High concentrations of salt in the soil can be toxic to plant roots and eventually cause the plant to die. Excess pesticides, a high fluorine content in water, softened water, and too high or too low pH levels can also result in brown leaves and houseplant decline.
Diagnosis: Salt buildup from fertilizer and softened water and other mineral deposits appear as a white or grey crystallized coating on plant leaves or a white crust on soil surface or the pot.
Treatment: Water thoroughly to keep salts from building up, avoid watering from the bottom or using pots with insufficient drainage. Use water that is low in salt and mineral deposits. Filtered or rain water are good choices. Follow the label instructions for applying fertilizers or plant nutrients and use pesticides as a last resort. Keep pots clean and repot with fresh soil every couple of years.
5. Pests and Disease.
If none of the four factors above appear to be causing the brown leaf tip problem, the culprit may be an insect pest or disease. There are usually additional symptoms, like little brown speckles indicating spider mites or white powdery areas indicating powdery mildew disease. For more information on diagnosing these problems see Preventing, Diagnosing, and Correcting Common Houseplant Problems and consult the Virginia Cooperative Extension, 2021 Pest Management Guide: Home Grounds & Animals for ways to manage plant disease, and common insects and related pests.
Now you are well on your way to keeping your houseplants healthy. Remember to inspect them often to make sure that they have the ideal growing conditions and enjoy them for years to come!
References
“Caring for Houseplants,” Trinklein, David H., University of Missouri, University of Missouri Extension, 7 Dec 2017.
“Diagnose Indoor Plant Problems”, University of Maryland, University of Maryland Extension, College of Agriculture and Natural Resources, 14 Jan 2022.
“Houseplant Woes,” Hoppers, Ashley, University of Georgia, University of Georgia Extension, Agriculture & Natural Resources Updates, 22 Dec 2020.
“Indoor Plant Culture,” Niemiera, Alex X., Virginia Tech, Virginia Cooperative Extension, Publication 426-100, 5 Nov 2018.
“Mineral and Fertilizer Salt Deposits on Indoor Plants”, University of Maryland, College of Agriculture and Natural Resources, 16 Mar 2021.
“Preventing, Diagnosing, and Correcting Common Houseplant Problems,” Kelley, Kathy, Penn State University, Penn State Extension, 27 June 2016.
“Repotting Houseplants”, Piedmont Master Gardeners, Ask A Master Gardener, 9, Nov 2021.
“Winter Indoor Plant Problems,” University of Maryland, University of Maryland Extension, College of Agriculture and Natural Resources, 7 Dec 2021.
