When the holidays are over, the tree is down and the tinsel is cleaned up, weíre left with our houseplants to carry us through winter. Now is a good time to examine your houseplants for insects and diseases. Judy Stevens offers these tips.
Q: My houseplant is wilting, whatís wrong with it?
A: It may be overwatered. Interestingly, overwatering is the most common cause of indoor plant problems. Waterlogged soil doesnít contain enough air for plants to breathe, so plants wilt and roots begin to rot. When wilting starts it may not be possible to save the plant by repotting it in dry soil, pruning the rotting roots and watering sparingly. New soil is essential as the excess water may have encouraged fungi and bacteria growth.
The amount of water required depends on the plant species. Ferns prefer evenly moist soil whereas cactuses and succulents should not be watered until the soil is completely dry. Most houseplants should be watered when soil is barely moist or almost dry to the touch.
Q: Should I fertilize my houseplants now?
A: Generally most houseplants are dormant or resting in the wintertime showing very little new growth. Donít fertilize now. When the days get longer in March and April, and your plant shows signs of new growth, you should start fertilizing. Carefully read the label on the fertilizer and follow directions verbatim. Over-fertilization can also kill houseplants.
Q: Why is my houseplant dropping leaves?
A: A lack of light may be one cause. The plant canít support foliage without adequate light for photosynthesis. The plant then drops its leaves to adjust the foliage it can support. If providing more light isnít possible, the loss of some leaves is not detrimental to the plant, but itís not as attractive as you may like.
Another reason for leaf drop may be humidity. Most houseplants prefer humidity levels of 40 percent to 50 percent, but most homes have a humidity level of only 10 percent to 20 percent in winter. Grouping your plants together will increase the relative humidity around your plants, but may also increase the likelihood of spreading a pest or disease .
To increase humidity, use a humidifier near your plants or place houseplants on trays or saucers filled with water and gravel or pebbles. Pot bottoms should always be above the water level.
Q: My plants get dirty. How should I clean them?
A: Dust and grease can accumulate on plants, clog plant pores and slow growth. Dirty plants also invite insects and mites. Large, firm leafed plants can be cleaned using a mild dishwashing soap and tepid water applied with a soft cloth. Finer leafed plants can be placed in the shower, just be sure to adjust the water temperature.
For specific houseplant questions, call Linn County Extension Horticulture at (319) 447-0647, from 10 a.m. to noon weekdays.Lisa Slattery is a Linn County Master Gardener.