1. Practice Prevention & Early Diagnosis
Stop a pest problem before it has an opportunity to start, urges Arthur Laster, president and owner of Plant Detectives Nursery and Garden Center in Chester, New Jersey.
"The single biggest mistake people make when dealing with pest problems on houseplants is not catching the problem quickly enough," he tells OrganicAuthority.com. "Close, routine inspection of one's houseplants can head off problems far more easily at an early stage. Pest problems such as spider mites will begin gradually, but can manifest rapidly. Most organic controls prove far more ineffective when a problem is allowed to go untreated for a week or longer."
2. Learn How to Inspect Your Houseplants
Organic gardening requires vigilance, so begin by inspecting the foliage on your indoor plants. Leaves that are off-color or washed out may be a sign of aphid, mite or scale infestation. The same holds true for loose foliage.
"Inspect the foliage and stems closely," Laster says. "Problems such as scale and aphids will be visible, whereas mites will be more difficult to spot." (A magnifying glass usually proves helpful.)
"Leaves dropping off the plants could also indicate a problem, but keep in mind that all plants lose foliage at certain times of the year," Laster adds. "This is particularly true for plants brought inside in the fall that have been grown outside during the summer months. Oftentimes, a plant dropping foliage can indicate a root problem, so the plant should be removed from its pot and the root system should be closely inspected."
3. Use the Right Soil
Garden soil is a no-no when growing indoor plants, as it often contains fungi, bacteria, insects and nematodes that promote disease. You must use an appropriate organic potting soil.
"Most potting soil mixes that are available at your local nursery supply store contain synthetic nutrients or biosolids, which are not allowed in organic production," cautions Rose Koenig, PhD, a plant pathologist and owner of Rosie's Organic Farm-a 17-acre farm in Gainesville, Florida, that produces a large variety of organically certified vegetables, cut flowers and herbs.
"Many people produce their own compost or worm castings, which they use as a potting mix," she tells OrganicAuthority.com. "Depending on the plant species that you are growing, this may or may not be an adequate potting mix. In general, a potting mix should provide good drainage and aeration to the roots. You do not want a compacted, heavy potting mix that holds excess water because this will usually promote the growth of root-rotting organisms.
"Adding vermiculite or sand to a homemade compost can help with aeration and drainage," adds Dr. Koenig, who just completed her term on the National Organic Standards Board. "Many people make their own potting mixes by combining peat moss, vermiculite and an organic amendment that provides some plant nutrients, such as compost, animal manures, naturally mined minerals, bone meal and feather meal. Alternatively, there are some companies that sell sterile potting soil that meets the National Organic Standards."
Specific products and manufacturers may be found by clicking here (PDF file).
4. Give Your Plants a Bath
Washing leaves will prevent pests from settling in and remove any unwanted insects that call your houseplants their home.
"If your houseplants are small enough, place them in the kitchen sink and spray them with a stream of water from your faucet," advises Brunhilde Pheets, a Los Angeles organic gardener with more than 20 years of experience. "If you have enough time and aren't in a rush, spray each individual leaf — both top and bottom. Then shake off the excess water, and leave the plant in the sink until it dries so it won't drip on countertops or floors."
For larger houseplants — or all houseplants during the summer months, regardless of size — take them outside and gently spray them with your garden hose. Again, wash both the tops and bottoms of leaves to cleanse them of dirt.
"They'll look much greener and healthier," Pheets says. "Just make sure to let them dry in an area that's not exposed to direct sunlight."
5. Place New Plants in Isolation
"When bringing a new plant into your home, it is a good idea to isolate it from your other plants for several days to be sure it is free of pest problems," Laster says. "It often takes several days for a new plant to exhibit a pest problem — especially if it's in its early stages."
Your primary goal: to keep existing houseplants healthy so they won't succumb to attacks from a new plant's pests.
"It would not be unusual for a new plant grown in a perfect environment to drop some leaves initially as it acclimates to its new home," Laster says. "But if it were to continue over an extended period, the plant may be telling you there's a greater problem — and that it shouldn't be introduced into your existing plant community until it is properly treated. Remember to purchase new houseplants from a reputable supplier, as this can prevent issues before they occur."