And you thought you had a brown thumb.
It turns out that the way many of us have learned to take care of houseplants isn't the way they need to be treated. Is it any wonder our plants die when we water them every Monday instead of when they're dry, or when we expose them to only a quarter of the light they need to thrive?
Most of us probably end up with the houseplants we have because we liked the way they looked in the store, or somebody gave us one as a gift.
But the way to do it, says Alan Stevens of K-State, is to wander the house with an eye to areas where a plant would improve the aesthetics. Then buy the type of plant that matches the conditions in each spot.
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I think I've done that with one plant in one spot in one house. All the other plants I've put in all the other spots have survived from sheer good luck. Or, more often, died from bad.
Stevens is director of the K-State Research and Extension Center in Olathe and recently gave a class to Sedgwick County's master gardeners about houseplants. Here is some of his wisdom.
Four elements in the environment need to be taken into consideration when growing houseplants: light, water, temperature and humidity.
* Light is the most important factor. A plant does best when it has light from five directions — all four sides and from above. A south window provides the most light, but it still only provides light from one side. The ugly backside of a plant blocking a window does not enhance a room. By the same token, you could add grow lights, but those generally don't add to the decor.
Forget spring cleaning — for the sake of houseplants, wash the windows in the fall and winter. Clean windows let more light in. And dust the leaves of the plants. Dust prevents photosynthesis. Don't use soap on the leaves, but a damp rag.
* There are two parts to watering.
1. Always water a plant in a pot to saturation and pour off the excess water. This goes even for cactuses. ("It doesn't mist or drizzle in the desert," Stevens says. "Rain always comes in a flood. Cactus and succulents store moisture is the difference.")
2. When do I water again? That's easy to say, hard to do. Do not water frequently and shallowly, as that only results in sealing the surface of the soil from air exchange.
In a 6-inch pot, water when the soil is dry 1 inch down. In a 10-inch pot, water when the soil is dry 2 inches down.
For a cactus, wait for it to dry out, and then wait a while more. (A handy tip for jade: Squeeze a leaf, and if it's hard, it has water stored in there.)
* The ideal temperature for most plants is between 65 and 75. Above 86 is harmful, and below 50 will result in chilling injury.
If you have a plant near a heat register, place it on an open stool with a deflector on the register so that air blows into the room from under the plant.
* Most plants don't care about humidity. Misting does nothing to raise humidity, nor do pebbles in a tray under the plant. But a humidifier in the room with the plant will help.
Sphagnum peat moss is the best growing medium; additives in potting mixes make it less expensive.
Repot in the spring. Repotting encourages growth, and fall going into winter is not the time for that. Go up no more than 2 inches in diameter with a new pot.
The best saucers have ridges to leave space between the pot and the saucer, and the best pots have little feet attached to the bottom to let water freely drain out (two smooth surfaces against each other is bad). It's best for a pot to have a center hole, side holes and holes low on the side of the pot for water drainage.
If you have a pot with no holes in the bottom, treat it as a saucer with very high sides.
Never put anything other than the potting soil medium in the bottom of a pot to take up space, including gravel. It can cause root rot.
Plastic or ceramic is a better material for a pot than clay or terra-cotta. The soil temperature varies in clay, and the bottom of a clay pot tends to stay moist. Salts also develop in clay pots.
Stevens' wife insists on clay because it's more natural than plastic. So he seals the insides of their clay pots to get the benefits of plastic. You can do the same by applying a sealer or roofing patch asphalt, with a disposable brush.
But: If you've learned to grow successfully in clay, don't switch now. Clay is an insurance policy for over-frequent watering, because it's more forgiving.
If you find a plant that seems very inexpensive, it's usually because it's been grown fast and hasn't been acclimated to indoor conditions for long. This plant will probably suffer coming into your house because its leaves are used to higher light.
"Stick with a store whose plants do well for you," Stevens says. A shaded greenhouse for growing is best.
Plants as gifts
If you receive the gift of a plant that has come from, say, a florist, its leaves likely will be polished. This gives a beautiful look, but the polish reflects light out, not allowing it into the plant. This is not a bad thing from the point of view of a gift. You've received something beautiful, and that's the main thing. It doesn't necessarily have to last a long time; you can view it more like a flower arrangement. The same goes for a pot that combines a variety of plants that may or may not have the same growing requirements.
* For very low light, grow the little watermelon peperomia, in a 3- to 5-inch-diameter pot.
* Chinese evergreen is the best-looking plant that does well in low light. A south window would burn it up. It's ideal across the room from a window. Can grow in eight hours of office light. Silver King and Queen are the best cultivars.
* Staghorn fern does well in indirect light.
* Variegated forms of arrowhead vine do better than the solids and brighten dark spaces. Some have a pink flush. They're slow to vine.
* Variegated Hawaiian schefflera is a great indoor plant that is an indicator of CO2 levels, even more sensitive than a detector. It drops its leaves overnight in the presence of carbon dioxide. The solid green variety needs high light, but the variegated variety can take medium light. It tends to get wide so it needs a lot of floor space.
* Pothos is the No. 1 houseplant seller, usually in a hanging pot.
* Rabbit foot fern is the best indoor hanging fern.
* Cast-iron plant takes the lowest light indoors. But it's ugly.
* Neanthe bella palm is an excellent small, slow-growing palm that can be divided.
* Areca palm is low-cost but undesirable.
* Bamboo palm is the best value. It grows tall but not wide and takes medium to high light. Costs about $60.
* Rhapis or lady finger palm is even better but costs more — about $125.
* The Rolls Royce of palms is the Kentia, the classic Victorian potted palm. A 3- to 4-foot plant runs about $300.
* Benjamin fig (ficus) drops half of its leaves when you bring it in the house in the fall but puts on new ones that are acclimated to the indoors.
* All parts of a dieffenbachia are poisonous.
* Every part of any lily is fatal to a cat, inside or outside.
* Poinsettias aren't poisonous.
Ward Upham of K-State has reported that researchers at the University of Georgia tested a number of common houseplants for their ability to remove indoor pollutants including benzene, toluene, octane, tricholoroethylene and alpha-pinene.
The researchers categorized the plants as superior, intermediate or poor with regard to how well they removed the pollutants.
Hemigraphis alternata (red ivy), Hedera helix (English ivy), Tradescantia pallida (wandering Jew), Hoya carnosa (porcelain flower).
Ficus benjamina (weeping fig), Polyscia fruticosa (Ming aralia), Fittonia argyroneura (silver nerve plant), Sansevieria trifasciata (mother-in-law's tongue), Gusmania sp. (type of bromeliad), Anthurium andreanum (flamingo flower), Schefflera elegantissima (false aralia).
Peperomia clusiifolia (peperomia); Chlorophytum comosum (spider plant); Howea belmoreana (sentry palm), Spathiphyllum wallisii (peace lily), Schefflera arboricola (Hawaiian elf schefflera), Codiaeum variegatum (croton), Calathea roseopicta (peacock plant), Aspidistra elatior (cast iron plant), Maranta leuconeura (prayer plant), Dracaena fragrans (corn plant), Ficus elastica (India rubber plant), Dieffenbachia seguine (dumbcane), Philodendron scandens (philodendron), Syngonium podophyllum (Nephytis, arrowhead vine), Epipremnum aureum (pothos), Pelargonium graveolens (rose geranium).