Houseplant how-to: Curing what ails them

Jade plant   Proven Winners

Houseplants are the only hope through the long winter for chlorophyll-addicted, greenery-loving gardeners.

We tend to have a few around after the holidays since poinsettias, amaryllis, cyclamen and succulents are popular gifts. The hope is that we will manage not to kill them – at least until spring rolls around. Keeping houseplants at their peak can be challenging, though.

The truth is our homes can be dim during winter’s short days and the relative humidity of heated spaces is often down around 10 percent, very like a desert. Running a humidifier or standing plants on a tray of moistened gravel will help.

Researching your particular plant’s needs should answer questions about what sort of light suits and how often water and fertilizer should be applied. When your plants fail to thrive, it’s often baffling to figure out why. Here’s a quick guide to solving common problems that indoor growers can face:

Problem: Lower leaves turn yellow and drop

Causes: Usually overwatering, but it could be a lack of fertilizer

Questions to ask: Is the soil soggy? Does my pot have adequate drainage holes? When was the last time I fed this starving plant?

Cures: Learn good watering practices and let soil surface dry out before re-watering. Repot in a container with holes large enough to assure fast drainage. Fertilize periodically, following directions on package.

Problem: Dying and dropping leaves throughout plant

Causes: Drafts and chilling temperatures. Compacted soil or poor drainage.

Questions to ask: Was this plant relocated recently? Is it near a frequently used door or an uncurtained window? Is the soil hard and difficult to penetrate? Is the soil constantly wet?

Cures: Move plant to a warmer, more protected location, away from windows and doors. Keep humidity levels up. Check that the pot is draining freely. Repot if soil is stiff and hard or pot lacks adequate drainage holes.

Problem: Dry, brown leaf edges or tips with a "crispy" burned appearance.

Causes:  Heat too high, humidity too low. Fertilizer build-up, often aggravated by dry soil. Can indicate sensitivity to fluoride in tap water.

Questions to ask: Can I relocate this plant to a cooler, more humid spot? Have I fertilized too frequently or failed to water regularly? Does my tap water contain fluoride?

Cures: Trim off badly affected leaves. Lower the temperature, raise the humidity and water consistently. If overfeeding might be at fault, water repeatedly to flush fertilizer from potting soil. If fluoride is present in tap water, use bottled or distilled water on plants.

Christmas cactus/Bugwood.org

Problem: New growth is weak, pale and spindly; small leaves are spaced farther apart on the stem than they were when you purchased plant

Causes: Excessive heat, aggravated by insufficiently bright light

Questions to ask: Is this plant living in a dim, dark spot?

Cures: This is a common problem in winter with plants grown in warm houses with low light levels. Prune weak growth. Move the plant to a cooler, brighter location or supplement natural light with artificial full-spectrum lighting.

Problem: Wilted leaves and stems

Causes: Lack of water, high temperatures, low humidity or poor soil. Overwatering can trigger wilting if waterlogged soil causes roots to rot, impairing their ability to convey soil moisture to plant tissues.

Questions to ask: Have I forgotten to water this plant? Is it in a hot, dry spot? Have I over-watered, leaving the soil soggy? Does water drain adequately?

Cures: Water if dry. Relocate plant to a cooler, more humid spot. If soil is soggy, withhold water until it dries out. Check condition of roots; trim black, rotten roots away and repot in fresh soil.

Problem: Buds drop before they open

Causes: Too warm, low humidity, uneven watering, too little water, shock from being relocated while buds are forming.

Questions to ask: Is it overly warm where this plant is growing? How consistent have I been about watering? Have I fiddled with the plant's location after buds began to appear?

Cures: Move the plant to a cooler spot and increase humidity. Water consistently and check soil moisture more frequently. Don't move plants around while they are preparing to flower.

Problem: Failure to bloom

Causes: Insufficient light. Too much high-nitrogen fertilizer. Failure to account for certain plant’s flower-formation requirements.

Questons to ask: Is this plant in a dim location? Is the nitrogen content of my fertilizer higher than other components? Does my plant need specific light intervals, complete darkness or a difference in night and daytime temperatures to trigger bloom?

Cures: Move plant to brighter spot. Adjust fertilizer to a balanced formula or one lower in nitrogen. Research whether your plant has specific needs in order to produce flowers. Orchids need a 10-degree drop between day and night temperatures. Poinsettias, kalanchoes and Christmas cactuses need 10 to 14 hours of dark for as much as two months to set flowers.