The persistent hum from your furnace might be the tipoff: We have again passed from summer when windows were thrown open to accept gentle breezes toward those blustery, bitter days that characterize winter in the Midwest.
As the weather changes, the whole environment we live in changes, too. While we accept this by putting on an extra layer of clothing, other organisms we live with take longer to adapt. Like our houseplants.
Many of us have a compound problem because our plants spent the summer lolling in the great outdoors, growing great amounts of new foliage that we would like to keep now that frost has visited.
The standard wisdom for keeping tropical and semi-tropical plants happy in the home is to place them where they will receive appropriate light; keep up the humidity through a humidifier, pebble trays or a grouping of many plants; water them as they need it, not on a regular cycle; give them no fertilizer until next March; and regulate the temperature as much as possible in the home and keep them out of cold drafts.
Not in the books
Those bromides are all true, but anyone who has nursed a Boston fern through a winter will tell you there are many out-of-textbook tricks that increase the success rate. Several experts were polled on their particular nuances.
Virginia Stauber of Morton Grove used to grow plants on her windowsills, but over time the sills sustained water damage that required professional repair. ”Now I buy long plastic windowboxes and set the pots in them,” she says.
She goes against conventional wisdom by cutting back many of her plants, realizing the stress they will encounter indoors. ”On asparagus fern, I whack it way back to 3 to 4 inches or it all turns yellow from lack of light and humidity. I cut ficus way back, too, to shape it,” she says.
Perhaps her most telling tip is how to get ferns ready for winter. But if you try this, make sure the weather is at least hospitable:
”I hang them in a tree and cut all the old leaves off the underside and all the little tendrils I cut off with some roots attached and tuck them in a new pot. That`s why it sends out the tendrils, looking to root them. Any time I buy a new one, I unpot it to see if it is planted in pure peat. I repot it in potting soil with peat and perlite added because once peat dries out completely, it is hard to rewet. It shrinks away from the side of the pot and water runs through but doesn`t remoisten it.”
Stauber also sprays every plant for bugs, takes it out of its pot and washes the pot before bringing the plant indoors. ”I wash the pots in a tub and check for sow bugs. I remove the dead leaves and debris on top of the soil. If you do that, you`ll eliminate a lot of problems come January and February,” she says.
Watch your plants
Adele Kleine of Winnetka has been moving plants inside since Labor Day, depotting for bugs but also to check root systems to see if repotting is necessary or can wait until spring. Despite the theory that plants shouldn`t be fertilized in winter, she gives her houseplants a feeding of 20-20-20 balanced fertilizer once a month. Her flowering plants, most of which have the luxury of extra light in her greenhouse, get feedings with a high-phosphorus 15-30-15 formula. She places cacti in the greenhouse and ignores them for December, January and February.
”The best advice I can give you is to look at your plants, run an eye over them,” she says. ”If the leaves look a little limp and curl under, it needs water, but if you`re overwatering, they`ll look like that too. Sometimes people have cache pots and don`t realize their plants are sitting in a puddle of water.
”In the dark days of winter, plants that are normally suggested for northern exposure can stand southern exposure because we get so little light.”
She also has a tip for those who grow the ubiquitous spider or airplane plant (Chlorophytum comosum): ”They have fleshy roots that hold a lot of water and don`t need to be watered as often as you think. You get the brown leaf tips from a too-wet or too-dry cycle when it really needs high humidity.”
Charles C. Powell and Rosemarie Rossetti, horticulture professors at Ohio State University and authors of ”The Healthy Indoor Plant” ($29.50 from Rosewell Publishing Inc., Box 2920, Columbus, Ohio 43216), oppose shipping plants outdoors for the summer. ”We feel strongly that if a plant is happy, don`t take it outdoors,” Powell says. ”If it`s dying inside, then you can take it out.” As far as acclimation, ”plants will readjust to a good inside maintenance station, but it won`t occur instantly; it will take about a month. Expect symptoms of readjustment such as leaf tips turning brown. Make sure the plants are never allowed to dry out.”
De-bugging
Almost without exception, they say, some form of livestock probably comes inside with the plants-aphids, whiteflies, mites, sow bugs, mealy bugs, scale and earwigs, to name a few. ”Using insecticidal soaps is the most universally effective yet least hazardous means of getting rid of insects, although other products are available,” Powell says. ”Soaps will work on mites, but you have to get on the undersurfaces of the leaves.” He advises checking package labeling for what plants not to spray.
”At a seminar we were at last weekend, we found people don`t understand light levels indoors versus outdoors,” Powell says. ”Even in dense shade, plants receive 1,500 to 2,000 footcandles of light, while a brightly lit interior is around 300.” At the other end of the spectrum, indoor plants in winter may receive more intense sunlight because the sun`s lower angle allows more light penetration into our homes. ”Direct sun is 600 to 700 footcandles and in winter that can heat the leaves, dry them out and fry the plant.”
Rossetti punctures another cliche of houseplants, that we tend to kill them from overwatering. ”With artificial heating, the humidity level goes down, causing the plants to transpire more. We need to supplement that with more water. People tend to overwater in summer and underwater in winter. More plants die from underwatering than the reverse. Also, we don`t fuss over our plants the way we once did. Watering once a week may not be enough.”
Julie Styczenski, assistant manager of the Amlings store in Elmhurst, uses a homemade device to see when her plants need water. ”You don`t want the plant to dry out except the upper third of the soil,” she says. ”I use a couple of little wooden sticks stuck down as far as possible along the side of the pot. I pull them up to see where the soil is stuck. If it clings all the way to the top, it`s still wet. If the soil sticks only to the bottom half, it needs water.”
Proper watering
Styczenski says ferns and palms benefit from more frequent watering to keep them evenly moist. ”Both are high light plants, and because the leaves are so thin, moisture tends to move out of them very quickly,” she says.
”The thicker the leaf, the longer the plant can hold moisture, as in succulents.”
And finally, checking in from hurricane-battered Florida is Joe Cialone, president of Tropical Ornamentals of Delray Beach. ”The biggest problem for temperature-sensitive plants such as aglaonemas (Chinese evergreens) and dracaenas is cold drafts from open doors. If an aglaonema gets one blast of air, you can kiss it goodbye. Tap water has to be watched also; some of it can be extremely cold and can cause damage when it hits those roots.” He also warns against planter boxes on cold floors and getting tropical plants too close to frosty windows.
”Because of lower humidity, you need more frequent watering in winter without exception,” Cialone says. ”Certain bug problems become more severe under low humidity on crotons, some palms and some dracaenas. If you keep your plants really clean by frequent wiping of the foliage, that`s as good a deterrent as any.”
There may be frosty days ahead with plenty of bleakness in the natural landscape, but that doesn`t mean we can`t have green in our homes. Keeping them green may be as simple as Virginia Stauber`s saying: ”Next to a green thumb is always a black forefinger, because if you push that finger down to the first knuckle and don`t find any moisture, it`s time to water.”
