HI – Darrell Blackwelder: Help houseplants transition back indoors

Published 9:39 pm Friday, September 22, 2017

Cooler fall temperatures and falling leaves are sure signals for those that have moved houseplants outdoors to strongly consider moving them indoors soon. Damage will occur to many houseplants when night time temperatures begin to dip down to the 40s.

House plants such as rubber trees, philodendron, pathos and even Christmas cactus are actually tropical understory plants. Their cell structures contain more oils and waxes than plants endogenous to the Piedmont. Waxes and oils within the cells solidify under waning night temperatures, rupturing the cell walls.  Cold damage is manifested by internal browning on the leaf margins of plants.  Rubber tree plants are easily damaged at temperatures of 42 degrees.

Unfortunately, indoor environments are a difficult transition for most houseplants coming in from a long summer vacation of optimum growing conditions.  Moving plants indoors from bright sunlight of nearly 10,000 foot candles to 5-15 foot candles will often initiate premature leaf drop.  Ficus trees, or weeping fig trees, are extremely sensitive to deviations in light intensity. These trees and other plants will almost always experience premature leaf drop when moved indoors. New leaves adjust well to low light levels.

It is important to emulate an indoor environment similar to the outdoors.  Move house plants to an area indoors that has high natural or indirect 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.  Implementing an electrostatic humidifier to the room is an excellent method of keeping the air moist.

House plants on outdoor vacation this past summer are also 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 recommended house plant sprays to control insect pests outdoors a few days before bringing them indoors for their winter rest.  Eggs and immature stages of spiders, ants and other insects may be lying dormant in the soil media of the house plant.  Plants with insects may want to drench the soil media three days before moving indoors with an indoor insecticide.  Drenches will control many but not all insects hibernating in the soil.  Always read and follow pesticide labels before applying any pesticide.

Fertilization is generally not recommended on house plants during the winter months. High soluble salt build-up from winter fertilization often burns the roots, reducing vigor and eventually kills the house plant.

Darrell Blackwelder is the retired County Extension director with horticulture responsibilities with the North Carolina Cooperative Extension Service in Rowan County.