Prevent leaf damage on houseplants

During the winter my houseplants are often a source of joy and a daily reminder that springtime and a new growing season is indeed coming. Houseplants actually benefit our indoor environments in many ways and this is why it is frustrating when they fail to thrive.

Leaf burn (leaf tips or edges turning brown) and leaf damage in general are common problems that can affect our indoor plants. Once the tip or a portion of a leaf dies, there is no way to help it return it to its normal appearance. Proper preventative care is the best way to prevent leaf damage and below are some tips that will help reduce the chances that a houseplant will suffer this kind of injury.

Low Humidity

Leaf or tip burn can have multiple causes

Low indoor humidity in one possible cause of leaf or tip burn on houseplants.

When indoor humidity is under 20 percent many houseplants will be injured. Most plants prefer humidity levels between 40 and 60 percent. It is possible to increase humidity around houseplants by using a room humidifier. These are readily available and easy to use. A room humidifier is the easiest way to increase humidity levels. Syringing is another possible method which involves spraying/misting plants with clean water on a regular basis. This removes dirt from leaves and increases humidity, but only for a very short time. This makes syringing fairly impractical for most homeowners.

Cold air drafts

Houseplants near windows with cold air drafts need to be carefully monitored to prevent injury. If too much cold air is coming in, the plant may need to be moved to a different location until warmer temperatures return. Houseplants vary in their tolerance to cold air and chill damage is most often appears as the yellowing of lower leaves and/or defoliation.

Fluoride or chlorine

Another cause of leaf burn and leaf damage in certain houseplants is fluoride and/or chlorine levels in tap water. There are several houseplants that are sensitive to fluoride and chlorine including Corn Plant (Dracaena), Ti Plant (Cordyline), Prayer Plant (Maranta) and Rattlesnake Plant (Calathea). Members of the Liliaceae (lily) plant family are especially sensitive to fluorides which is why they often develop tip burn even when properly watered and fertilized.

One easy way to avoid or reduce leaf burn from chlorine or fluoride is to water indoor plants with collected rain water. Buckets or rain barrels can be used to collect the water during the growing season. During winter when rainwater isn’t as available, you can use distilled water or simply draw tap water for your plants the day before you plan to water them. A full day of evaporation will clear the water of a majority of chlorine and fluoride and give enough time for most minerals to settle harmlessly to the bottom. Plan to discard the bottom one to two inches of water in the container.

Salt build-up

It is a good idea to prevent salt and mineral build up in general in houseplant soil mixes. Houseplants have a certain soil volume that doesn’t change until a plant is repotted. Salt build-up can be a crucial concern especially if plants are fertilized regularly. Fertilizers are salts and these salts build up slowly over time. Salt and mineral build up may harm plant roots and lead to scorched leaves and unhealthy plants. It is best not to overfertilize houseplants and also to avoid watering houseplants with water that has passed through a water softener. Both practices will add to the problem of excess salts in the root zone of the plant.

Salt buildup on potting soil can eventually damage houseplants

Leaching out an overabundance of salts every 4 to 6 months can be an important practice to ensure the health of our houseplants. Leaching is not a complicated or difficult process. It consists of adding enough water to wash out excess salts.

How much water is enough? Add the amount of water to the potting mix that would equal to twice the volume of the pot. A bathtub or sink can be used for this process. Water must be added slowly so that it doesn’t overflow the rim of the pot. If salt has formed a crust on the surface of the soil, remove it but don’t take more than 1/4 inch of the underlying media.

In severe cases of salt build-up, it may be best to carefully repot the plant in the springtime with fresh potting medium to provide it with a new start.

Here is a chart to help diagnose other common abiotic houseplant problems:

SymptomCommon Cause
Leggy/spindly plantsNot enough light or poor lighting conditions
Few flowers with a lot of growthToo much nitrogen fertilizer
Few flowersPoor or incorrect lighting
Leaves turning yellowOverwatering
Not enough light
Not enough fertilizer/nutrients
Relative humidity is too low
Soil drains poorly and remains wet for too long
Low temperature injury resulting from a draft such as an open door, window, or air conditioner
Plant was moved and is adjusting
Scorched leavesToo much direct sunlight
Brown leaf tips/edgesChemical burn from overapplication of pesticides or fertilizer
Watering with soft water/plant is sensitive to chlorine or fluoride in water
Soil remains dry for extended periods of time
Temperature or relative humidity is too low
Small leavesSoil remains either too wet or too dry
Weak growthIncorrect or poor lighting
Root system is damaged from being kept too wet
Wilting plantSoil remains either too wet or too dry
General defoliationPoor lighting conditions
Injured by low temperatures