Tips for Keeping Houseplants Pest Free
by Don Janssen, Extension Educator
Scales on the stem of a houseplant
Nobody wants to use pesticides on their houseplants. Even people who are willing to use insecticides or fungicides on landscape plantings outdoors usually draw the line when it comes to spraying inside their homes.
Fortunately, with a little care and commitment to watching plants closely, you CAN avoid the use of pesticides indoors. Of course be willing to thrown out a plant or two in order to protect the others.
The best way to deal with insect pests and foliar diseases is to avoid them in the first place. And that's not really too difficult to accomplish if you're careful.
Be picky about which plants you bring into your home. When you buy a new plant, examine it closely to make sure it's not carrying any "hitch hikers" with it. Watch out for discolored or mottled foliage, fine webbing, or signs of sticky exudate. And be sure to check the undersides of leaves, not just the tops. Don't take a chance on introducing problem plants into your home.
If a friend offers to give you one of his or her plants, or a cutting from one, remember to be wary. Examine those plants at least as carefully as you would those from a commercial source.
Choose houseplants well-suited to the indoor environment you can provide. It will go a long way towards avoiding problems. Healthy, actively growing plants that receive plenty of light are in a better position to fend off insects and diseases. That means you must grow your houseplants in reasonably bright locations, or supplement whatever amount of natural daylight they receive with an appropriate electric light source. Fluorescent light tubes are the least expensive good source of light for indoor plants. Specialty catalogs also offer metal halide bulbs and high pressure sodium plant lights that are very bright and long-lasting, but considerably more costly.
Prevent root rots by watering properly. Rather than watering by the calendar, water whenever your plants need moisture. Always water thoroughly, but check the soil to make sure it has dried before you water again. How much it needs to dry depends on the type of plant and size of its container. Never water when the soil surface still feels moist.
When it comes to indoor plants, regular "housecleaning" activities mean more than keeping plants looking their best. Dust and dirt accumulating on the foliage creates a favorable environment for insect pests. By washing the leaves periodically you not only get rid of dust, you may be eliminating some mites or insects in the process.
Don't use a feather duster or fluffy dusting wand to clean your plants. If there are any mites, insects, or tiny eggs present, you'll end up spreading them from plant to plant.
Even though it's important to wash houseplants often enough to eliminate dust and grime, it's not a good idea to mist them frequently. Moist leaf surfaces allow fungal and bacterial organisms to get established. By keeping leaf surfaces dry most of the time, you'll reduce the likelihood of disease.
Give them their space. Locate houseplants so there's ample air circulation to help prevent powdery mildew. When you group susceptible plants such as begonias, African violets, or grape ivies too close together, not only are they more likely to develop mildew, but reproductive spores are more easily spread among them.
Keep houseplants indoors, year-round. Plants will put on lots of new growth when they spend the summer months outdoors on a porch or in the yard, beneath a shade tree. The obvious downside, however, is that they're exposed to large numbers of insect pests which may hitch a ride indoors with them in autumn.
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