Diagnosing house plant problems can be complex. Wilting or partial wilting will often be the result of improper water relations in the plant. If sudden wilting is diagnosed, check the roots, pot or soil for the trouble. Some common causes are a lack of water, excess water, root rot, too much fertilizer and/or a salt buildup. Check the cause by pressing your finger, up to the first knuckle, into the soil. If the soil is dry to this depth, the plant needs water. If the soil is wet, too much water in the root area may be the problem.
Plants, which are pot bound, may wilt because the roots are strangling each other or show yellowing and death of lower leaves. Do not be afraid to remove the plant from the pot and examine the roots to see if they are too dry, too wet or diseased. To remove, merely invert the plant and lightly tap the edge of the container on a solid object while holding the plant and soil ball. You may find the soil mass is completely enveloped in roots and the plant needs repotting. Healthy roots and root tips will be white or cream-colored. Rotted roots are a brown-black color and may appear slimy. Rubber plant, Dracena, Diffenbachia and other woody plants are especially prone to this problem. Occasional lower leaf drop may be normal.
Sudden loss of leaves is frequently caused by a rapid temperature change. It may also be caused by such factors as prolonged hot or cold drafts, dry air, and exposure to gas or furnace fumes or by changing the location of the plant from a sunny to a dark location. The weeping fig frequently has sudden leaf drop when moved to a location with lower light intensity.
Yellowing or death of leaves may indicate a nutrient deficiency, usually nitrogen or iron. If the foliage does not appear greener after three to four days, do not add additional fertilizer. Yellowing of all leaves and poor growth may be due to excessive soil moisture and/or root rot. Some plants such as the Norfolk Island pine and Boston fern require an acid soil medium. This can be achieved by using a potting mixture high in peat and by using an acid fertilizer. Most well water is alkaline, so regular use of an acidifying fertilizer would be advantageous to plant growth.
Bronzed or abnormally reddened leaves indicate cold temperature damage or a deficiency of phosphorus or potassium. Check the recommended temperature range for the plant. Unnaturally, small pale leaves and spindly plants are most generally the result of insufficient light. This is especially common during the winter or when outdoor or greenhouse grown plants are brought into the home. Small leaves might also indicate a need for fertilizer.
Brown leaf tips and margins can be caused by exposure to hot dry air, improper watering, insect feeding, salt accumulations or objects rubbing against the leaves. Water which is chlorinated or contains added or natural amounts of fluoride can harm sensitive plants. Perlite (the white material in many potting mixes) and fertilizer products containing fluoride may release enough fluoride to harm sensitive plants. Spider plants, especially the variegated variety, are very sensitive to fluoride and are often seen with leaf-tip burn. Occasionally flushing the soil should help to reduce a fluoride salt buildup. Other leaf spots, varying in description, may be caused by aerosol products, hot grease in the kitchen area, cold water (especially on African violets and gloxinias) or the sun shining on wet leaves.
