What Causes a Houseplant's Leaves to Fall Off?

Moisture

• Both overwatering and underwatering a houseplant causes the leaves to fall. In fact, these are the most common reasons for leaf drop. The surface of the soil can feel dry, but if you dig below the soil line, it is still moist. Push a finger into the potting soil to the first knuckle to accurately assess moisture. If the soil is wet, delay watering. Not having enough moisture is also a contributor to leaf drop. If the plant is thirsty, it will get rid of leaves to try to conserve energy and stay alive.

Fertilizer

• Over-fertilization and under-fertilization may be reason for leaf drop. Leaves will yellow or pale and fall if the plant doesn't get enough nutrients. Houseplants benefit from fertilizer application very one to two months and only when the plant is in growing mode. Avoid fertilizing a plant when it is in dormancy for winter. Loss of lower leaves may indicate a nutrient deficiency. The plant stops nourishing the oldest leaves to save the newer and stronger ones.

  Too much fertilizer often manifests itself by leaving a white, crusty line on the pot or in the soil. This is a deposit that must be removed by flushing the soil with water until the deposits wash away.

Pot-bound Plants

• Plants that have grown too large for their pot may drop leaves. The roots become crowded, or pot bound, and do not absorb nutrients and moisture. The plant tries to survive by dropping older leaves. Place the pot on its side and gently tug the plant out. If roots are circling around the sides of the pot, or there seems to be a small amount of soil for the plant, repot it in a container that is 1 to 2 inches larger.

Environmental Changes

• Some plants stress out from any type of change. Shedding occurs when you bring the plant indoors after having it outside all summer. Humidity levels might also be different inside than out, and this causes problems. To create more humidity, keep plants in the kitchen or bathroom or fill a tray with pebbles and partially cover them with water. Place the plant on top and keep water in the tray just low enough not to be absorbed by the plant. The plant will usually adjust to light conditions in about three weeks.

Other Causes

• Drafts cause leaf drop, so keep houseplants away from doors, windows, air conditioners and heat registers. Cold temperatures may also cause houseplants to lose leaves. Check windowsills for drafts or cold air.