Houseplants suffer in dry heat as people do

Make sure moisture and light can still reach potted plants

In The Garden

December 07, 2003|By Beth Botts | Beth Botts,Chicago Tribune

Your home, with its warm, dry air and handsome window treatments, may be a delight for people. But to a houseplant, it can be a hostile environment.

Many of the plants we like to grow indoors hail from tropical, subtropical or desert lands where they evolved to need more light and much better drainage than they typically get in the living room. A plant that comes from a moist rain forest can have a hard time in the dry air of a centrally heated apartment.

So how can you help plants survive in your home? "The best way to have success with a houseplant is to do a little bit of research and find out where the plant came from, and try to emulate those conditions," says Scott Wenthe, manager of horticulture at the Peggy Notebaert Nature Museum in Chicago.

Imagine, for example, that you were a moth orchid (phalaenopsis). In your native habitat in an Asian forest, you would be an epiphyte, living well above the ground, perhaps using your exposed roots to cling to the crotch of a tree. You would get strong light all day, filtered by the overhanging tree boughs. The air would be moist. You would be drenched by frequent rains, but you quickly would be dried by the breeze, so your roots always could breathe.

In someone's home, you would need similar conditions: Bright filtered light, high humidity, steady warm temperatures, watering that never submerges your roots and excellent air circulation.

It's easier to choose a plant that will do well in your home's environment than to try to change your conditions to suit a picky plant. Here are some things to think about as you assess your home's plant habitat:

Light: It's the foremost need of any plant. How much you can offer depends largely on which way each window faces. A south window offers bright light; a north window, low light; east and west windows, part light. Still, "plants that are on a windowsill receive a fraction of the light that is available outdoors," Wenthe says.

Plants have different light needs. Blooming takes a lot of energy, so flowering plants need more light. Many foliage plants have become favorite houseplants because they can get along with less.

Most cacti and succulents hail from bare, arid areas and need the full sun of a south window, says Steven Meyer, horticulturist at the Lincoln Park Conservatory in Chicago.

Water: The No. 1 reason for houseplant death is overwatering. Plants can drown if their roots are swamped and can't get the air they need.

Different plants need different amounts of water, so "don't water your plants on a regular schedule. Water them when they need it," Meyer says. For most plants, that means water when the soil is dry to the touch.

Let the water soak through the soil, and then drain it out of the saucer. And "don't water houseplants with cold water; it will shock them," Meyer says.

Soil: It's best to use sterile potting mix, which drains well and has no risk of transmitting disease. It has few nutrients, though, so plants must be fertilized when they are not dormant.

Fertilizer: Plants in pots need the nutrients provided by a good all-purpose houseplant fertilizer, but they can be overstimulated by too much fertilizer, especially in winter.

In nature, plants go into dormancy in winter. "There are fewer hours of daylight. The plant's growth slows," Meyer says. "So you should slow down on water and fertilizer." Resume regular fertilizing, at half the strength suggested on the label, in midspring.

Temperature: Most house-plants will do well in the range of temperatures that people like, Wenthe says. Just be sure to protect them from drafts or from sudden changes in temperature. Some plants, such as Ficus benjamina (a tree native to southeast Asia), will drop their leaves if stressed by sudden temperature changes.

Humidity: The colder air is, the less humidity it holds. In winter, we take dry, cold outdoor air and heat it in our homes. This dry air suits succulents, such as aloe vera (native to northern Africa).

Houseplants that come from rain forests do better with a humidity boost. An evaporative humidifier works well. Or, create a zone of higher humidity by placing plants on a tray of pea gravel filled with water, Meyer says.

Gathering houseplants into one area also helps, creating a zone of higher humidity, Meyer says.

It's not hard to find a houseplant whose needs are modest. But every houseplant needs a little understanding.

The Chicago Tribune is a Tribune Publishing newspaper.

A few of the fittest

Some plants are more tolerant of home conditions than others. Here are a few of the toughest survivors.

* Boston fern (Nephrolepis exaltata): Native to Hawaii, where it lives on the forest floor, the Boston fern has been a popular houseplant since Victorian times. It does well in the low light of a north window, but it likes steady moisture and high humidity.

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