From the Ground Up: Winter Care for Houseplants
by: Judy Stevens, ISU Extension Linn County Master Gardener
When the holidays are over, the tree is down and the tinsel is cleaned up, we're left with our houseplants to carry us through winter. Now is a good time to examine your houseplants for insects and diseases.
Q: My houseplant is wilting, what's wrong with it?
A: It may be over-watered. Interestingly, over-watering is the most common cause of indoor plant problems. Water-logged soil doesn't contain enough air for plants to breath, 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 cacti 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. Don't 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 the 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 can't support all of the foliage without adequate light for photosynthesis. The plant then drops its leaves to adjust the foliage it can support. If providing more light isn't possible, the loss of some leaves is not detrimental to the plant, but it's not as attractive as you may like.
Another reason for leaf drop may be the humidity of the home. Most houseplants prefer humidity levels of forty to fifty percent, but most homes only have a humidity level of ten to twenty percent in winter. Grouping your plants together will increase the relative humidity around your plants, but may also increase the likelihood of an infested plant spreading a pest or disease to other plants.
To increase humidity, use a humidifier near your plants or place houseplants on trays or saucers filled with water and gravel or pebbles. The bottoms of the pots 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 prior to showering your plants.
For specific houseplant questions, call ISU Extension Linn County Master Gardeners at 319-447-0647, from 10am-Noon weekdays. Or send an email with your question to firstname.lastname@example.org.
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