Houseplants Under Lights

Lesson 4: Proper Plant Selection and Care

Cultural Problems

Goal: Learn to differentiate between cultural problems and actual diseases or pests

No gardener likes to think about plant diseases or pests. We also don't like to feel that we failed to provide the right conditions for our plants to reach their optimal size and flowering capacity. Unfortunately, cultural difficulties, diseases and pests are frequent problems whether you garden indoors or outdoors. Learning to determine the cause of a plant's poor performance is necessary if you are to have healthy plants. Prevention is always easier than curing problems after they occur. Many symptoms may be the result of several causes. There are diseases caused by viruses or bacteria. Insects cause other problems. Some cultural problems caused by improper watering or fertilizing was already been discussed in lesson 4.

Frequent Cultural Problems & Their Possible Causes

Yellow leaves: Hard water used for plants that don't like lime or calcium in their potting media. If the leaves fall off the plant, over watering and cold temperatures are the most likely causes.

Green leaves on variegated plants: Normally, too little light causes this problem.

Spindly growth, small leaves: Too high temperatures, too wet potting media, too little fertilizer or too little light. Read in detail about your plant and determine the most likely cause of the problem. You may have to become a detective to solve this problem.

Curling leaves: Cold temperatures, overwatering, or cold drafts (from a door or window). Leaves curling up may need more light while those curling down may need less light.

Brown spots on leaves: Brown spots that easily crumble are usually caused by too much sunlight. Soft, cork-like brown spots are caused by overwatering.

Temperature and Watering

Many cultural problems are caused by improper temperatures combined with improper watering. I strongly suggest you consider this possibility before blaming any other cause. Watering a plant with hot water can quickly kill it. Alternatively, watering a plant with ice cold water (even on a hot, summer day) will shock it too.

If the plant prefers to be kept cool, keep the potting media just moist. Overwatering combined with cool temperatures almost invariably leads to rotting roots, leaves and stems. Keeping a plant too warm with too little water may quickly cuase the plant to wilt. Some plants, once wilted, cannot be revived. These problems are best avoided since either extreme will most likely kill your plant. Hot air or cold air blowing on a plant will have the same effects as too cool or too warm temperatures combined with improper watering.

Note: Carefully review lesson 4 on watering, pH, and fertilizing. Note the symptoms listed there for problems on over or under watering, and over or under watering.

Until you properly identify a plant, it is often impossible to determine exactly what is wrong. The Tropical Foliage book lists problems with each plant species discussed. Refer to this or another reference book to determine potential problems. Then, use your magnifying glass to study the problem closely. Horticulturists and commercial growers often have to come up with educated guesses and experiment in order to find the perfect method for growing a plant.

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