Garden Column for the Salisbury Post

Darrell Blackwelder

October 17, 2003

    Now is the time for houseplant owners to move their plants indoors to avoid cold damage. Temperatures dipping down to the forty degree range have the potential to damage some house plants. House plants such as rubber trees, philodendron, pathos and even Christmas cactus are actually tropical under story plants. The cell structures of these plants contain more oils and waxes than plants of our climate. Waxes and oils within the cells solidify under cool temperatures, rupturing cell walls. Cold damage is manifested by internal browning on the leaf margins of plants. For example, a rubber tree plant is easily damaged at a temperature of 42 degrees.
    The indoor environment is a difficult transition for some houseplants. Moving plants indoors from bright sunlight of nearly 10,000 foot candles to 5-15 foot candles often initiates premature leaf drop. Ficus trees or weeping fig trees is one example of a house plant that is very sensitive to deviations in light intensity. These trees and other plants experience premature leaf drop. New leaves adjust well to low light levels.
    House plants should be placed into an environment similar to the outdoors. Move house plants to an area indoors that has high natural light. Avoid placing plants near drafty doors or forced air heating vents.
    Occasionally mist house plants or place groups of plants on pans of rock filled with water. Evaporating water increases the level of humidity around the plant. Of course, adding an electrostatic humidifier to the room is an excellent method of keeping the air moist.
    House plants on an outdoor vacation this summer were subjected to a number of insect pests. Check house plant foliage and stems for aphids, scales or other insect pests carefully before bringing indoors.
    Use house plant sprays labeled for indoor plants to help control insect pests. Eggs and immature stages of spiders, ants and other insects lay dormant in the soil media of house plants that spend the summer outdoors. It is often beneficial to drench the soil media a week before moving indoors with an insecticide labeled for indoor use. Drenches kill most, but not all insects hibernating in the soil. Always read and follow pesticide labels before applying any pesticide.
    House plants grow very slowly if at all during the winter months. Therefore, fertilization while indoors is generally not recommended. High soluble salt build-up from winter fertilization burns the roots, reducing vigor and eventually kills the plant.