University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article

Dr. Leonard Perry, Extension Professor
University of Vermont
Whether you bought new houseplants recently, or have some several years old, if they aren’t looking right you may be able to figure out the problem yourself by a simple diagnosis.  There are several symptoms to watch for relating to leaves, growth, and flowers if appropriate.  Unless you see one of the main pests—aphids, scales, spider mites, or mealybugs—the problems likely are caused by poor culture (often called “physiological”).  Diseases, such as leaf spots and root rots, often come about as a result of poor culture.

Probably the number one cause of problems is overwatering.  This can lead to most problems, except bending or curling leaves, or leaf spots.  Even if a plant wilts, this may be a sign of overwatering.  Roots may be waterlogged and rotting, so unable to take up water even if the soil is wet.  If in doubt about whether to water, don’t, and wait a day or two.

If a plant is wilted, and the soil is dry, it likely needs water.  Other causes of wilt may be too much light or too high temperature, too much fertilizer (burning the roots so they don’t function), compacted soil (water isn’t absorbed well), and drafts (this is especially a problem on tender plants such as poinsettias).

Yellowish green (often called “chlorotic”) leaves are most often a sign of low fertility.  Other causes though might be too much or too low light or temperature, too much water or fertilizer, compacted soil, or air pollution (as from gas leaks or incomplete burning in stoves). 

If leaves are starting to drop, are all dropping or just older ones?  If the latter, this may be natural as the plant grows.  Too little light, too high temperature, or root problems from improper watering and fertilizer also may be to blame.  Too much or too little water, too much fertilizer, or air pollution may be the cause if suddenly all leaves begin dropping off, not just the older ones.

Often indoors growth may become weak and thin, and new leaves small.  If this is the case, examine whether plants are getting too little light, too high temperatures, or both.  Lack of fertilizer, or compacted soil, also may cause weak growth.  If just the new leaves are small, make sure you don’t have air pollution.

If growth has stopped, or in the worse case the plant died, this could be from low temperatures (as exposing tender plants to freezing between a store and your car, or in an unheated car or garage).  Symptoms from cold temperatures are usually sudden.  Slower causes of no growth or death include overwatering, too little water, or too much fertilizer.

If your plant is supposed to flower and has buds, but they don’t develop and drop off, most any cause except too much light may be to blame.  If flowers don’t last as long as they have in the past, or come and go quickly, make sure the temperature isn’t too high, the plants aren’t too dry, drafts aren’t affecting them, or there isn’t air pollution.  If there aren’t any blooms, and there should be, plants may have too low light, too much heat, or both.  Some plants form flowers only when the day (actually night) is a certain length.  Poinsettias, in general, need at least 14 hours of uninterrupted darkness during a 10-week period in the fall in order to flower.

Plants often tell you what is wrong by their symptoms.  If you want to make sure of your diagnosis, or can’t figure it out, check with your local greenhouse or garden center professionals.

Return to Perry's Perennial Pages, Articles uvmext logo