Here are some of the most common cultural causes of ailing houseplants and what to do about them.
Inconsistent watering is perhaps the number one cause of a houseplant’s demise. When a plant is allowed to dry out the roots begin to die. The potting medium is then saturated with water with hopes that it will recover. Since some of the roots are no longer functional, the plant cannot take up this excess water and if left sitting in this saturated medium more roots will perish from lack of oxygen. The plant will still look wilted and may receive more water, perpetuating the cycle. Plants that are overwatered often exhibit black edges along the leaves, stems and petioles. Roots also blacken.
If you suspect a plant is being overwatered, first check that the pot has adequate drainage holes. Next take the plant from the pot and look at the potting mix and the roots. If the roots are damaged, trim away the brown or black roots and repot in a container just large enough to accommodate the smaller root system. In some cases a more porous potting mix is called for and these might have more perlite, composted bark or sand in them. Keep the newly repotted plant moist enough to prevent wilting and encourage root growth.
Check potted plants every few days to determine their watering needs. In general, plants needs to be watered more often in warm, sunny weather and less often during the cool, dimly lit winter months. However, in homes with wood burning stoves or forced hot air, the plants can dry out pretty quickly even in the winter. Brown leaf tips often indicate not enough water. Do not let your plants get too dry.
Lack of humidity, especially in the winter, frequently causes leaf and/or bud drop. Leaves may also curl under and crack. To raise humidity levels arrange plants in groups, mist regularly or place pots on a tray of pebbles to which water is added. Do not let the pots sit in the water. A humidifier can be used.
Especially during the winter, some plants will bend toward the light, have pale leaves, spindly stems and few or no flowers. This is due to lack of light. Move the plant to a brighter spot and when new growth is produced, some of the more spindly stems can usually be pruned out.
In cases where no brighter spot can be found, place the plant within 3’ or so to a lamp and keep it on for several hours each evening. Better still purchase a wide spectrum or grow light bulb. They are available in sizes that fit regular lamps.
Sometimes a plant’s leaves will pale noticeably or turn purplish while situated in strong light. This usually means that this particular plant has a lower light requirement and should be moved into a less brightly lighted area.
If the edges of leaves and stems turn black and die, much the same as overwatering symptoms, excessive fertilizer use may be to blame.
Fertilizers high in nitrogen may promote lush vegetative growth at the expense of flowering. For blooming houseplants, select a fertilizer with more phosphorus than nitrogen.
Because of their limited growing space, houseplants do need to be fertilized on a regular basis, usually every 2 to 4 weeks when actively growing and less, if at all, during resting periods. It is better to use a quarter to half strength fertilizer solution more often than a full strength one at prolonged intervals.
Never fertilize a dry plant. Water it first and then fertilize a day or so later.
Pale leaves and slow growth indicate a need for more frequent fertilization.
Bud and leaf drop can also be due to drafts. Avoid locating plants near outside doors or loose fitting windows during the cold winter months.
Many plants are tolerant of a variety of conditions; others are more specific in their demands.
Despite good cultural practices, pests and diseases at times may appear. Chemical control should be used only after all other methods have failed.
For pesticide information or other questions please call toll free: 877-486-6271.
UConn Home and Garden Education Center, 2018
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