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Winter Care of Indoor Plants
by Sarah Browning, UNL Extension Educator
The shortest day of 2011, December 22, also called the winter solstice, has passed. This means that we can look forward to gradually lengthening days until June 2012. But all the cloudy days, with low light intensity, yet to come for Nebraska from January through March, make it difficult to notice the lengthening of days.
This time of year can be difficult for houseplants. They may have different water requirements from what was needed during summer's rapid growth phase; plus low light levels, cold temperatures near windows, dry indoor air, hot air from heating vents and cold drafts from doors all create challenging growing conditions.
Avoid Overwatering
More houseplants die from overwatering than from any other cause. Adjusting your watering routine based on the plant's use of water. Most plants benefit when the soil is allowed to dry slightly between waterings. This dryness ensures that oxygen penetrates to the plant's root system, oxygen that is just as essential for good plant growth as water. Often a plant can be allowed to wilt slightly before it is watered; thus giving an indication when water is needed.
Water Plants Thoroughly
No matter if you are growing a cactus or an azalea, always wet the entire root ball when you do water. This ensures that excess fertilizer salts that have built up in the soil are leached away. Fertilizer salts can burn roots resulting in dried leaf edges and wilting plants, even though they seem to have plenty of water.
The following two methods are great for watering houseplants. First, place the entire container in a sink filled with water and do not remove it until air bubbles have stopped coming from the planting container. Then place the container in an empty sink and allow it to drain for several minutes.
A second method is to place the container in an empty sink and pour water on top of the soil until water begins to drain from the bottom of the pot. Water the container once more and allow the excess water to drain away.
Reduce Watering Frequency
The best way to limit the amount of water a plant receives is to reduce the frequency of watering, not by applying smaller amounts of water at your normal summer frequency. A plant that needed watering twice a week during summer, may only require watering once every 7-10 days during winter.
Monitor plants carefully during winter, and test the soil moisture level before watering. If the top one-inch of soil feels dry or the plant begins to wilt slightly, most plants will be ready for another watering.
Lighting
Too much or too little light is the second most common reason for houseplant death. Match your plants light requirements to those available in your home, and provide supplemental lighting if necessary for high light plants, such as hibiscus, weeping fig or croton. Plants that are not receiving enough light often become tall, with weak spindly stems, and stop blooming. Variegated plants often have poor leaf color. High light plants can be moved closer to windows, but be careful not to get too close. Older, single pane windows get very cold in winter and cause death of leaves that touch the glass. Don't pull down window shades with the plant next to the window. This can trap too much cold air around your plant.
Fluorescent lights provide a good spectrum of light for houseplants if supplemental lighting is needed. Place them about one foot away from the plant, and use a timer so the lights are on about 16 hours each day. Incandescent lights have a poor light spectrum for houseplants, resulting in tall, spindly weak stems.
Humidity
Also keep in mind that some plants, like ferns, Rex begonias, Prayer Plant and Calathea to name a few, require high humidity to grow well. Indoor humidity levels are usually lower than those in a greenhouse, in fact during winter when furnaces are running, indoor air can be as dry as desert air. Considering that most houseplants are actually tropical plants adapted to rainforest or riverside humidity levels makes it easy to see why growing some plants indoors can be such a challenge. Low humidity results in marginal leaf burn of high humidity plants.
Place these plants in a bathroom or kitchen; rooms normally more humid than the majority of the house. Or use a cloche, a tall, bell-shaped, glass covering, that can be place over plants to maintain higher humidity around the leaves.
Fertilization
Avoid over-fertilization. Plants will no new growth in winter do not need fertilization. Actively growing plants can be fertilized about once a month. Burned or dried leaf margins and wilted plants can also be a sign of root damage to the plant caused by salt buildup in the soil from over fertilization.
Periodic leaching of your plants will help reduce the buildup of fertilizer salts. Put your plant in the bathtub or a deep sink. Mix 1 teaspoon Epsom salts in one gallon of water and pour the mixture into the plant's pot, a little at a time- you don't want to wash the plant away!- until water starts to come out the bottom drain holes. Allow it to drain away. Do this several times to each plant. The magnesium in Epsom salts will attach to the salts and help pull them out of the soil.
Finally, keep plants away from cold or hot drafts, both of which can cause leaf problems.
Cactus Care
Cactus thrive if kept cool during the winter months. Lower temperatures encourage the development of sturdy plants and stimulate flower bud development. Most cactus do best at temperatures from 45-55 degrees Fahrenheit, however, they still require high light conditions during this period, so a cool bedroom with a south facing window would be ideal.
This resource was updated December 2011 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office
Contact Information University of Nebraska-Lincoln
in Lancaster County
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A,
Lincoln, NE 68528 | 402-441-7180
