University of Illinois Extension

 

Sharon Yiesla
Unit Educator, Horticulture
Lake Unit

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House Plant Care

houseplants have become a staple in many homes. Since the home often provides a less than ideal environment for these plants, it is important to select houseplants carefully. Select those plants that will grow in the environment provided.

The Houseplant Environment

Light: Light is often a limiting factor in growing houseplants. Most houseplants grow best in bright, indirect light, but many plants can adapt to various light levels. The amount of light in a house varies from room to room, depending on the number of windows in each room and the direction in which they face.

North-facing windows tend to provide the least amount of light. Plants that are tolerant of low light conditions may be able to grow in north-facing windows, but they should be placed within one foot of the sill. The light level may be slightly higher in summer when the sun rises from the northeast.

East-facing windows provide indirect light through most of the day and cooler temperatures. Flowering houseplants, which need cooler temperatures often do well in east facing windows.

South-facing windows provide the greatest amount of light, especially in winter, when the sun is lower in the southern sky. Plants that need direct light or high levels of light do well in southern exposures.

While the light is intense in a south-facing window, so is the temperature. If a plant cannot tolerate high temperatures, it can be placed to the side of the window where it can receive bright, indirect light. Sheer curtains or mini-blinds can also be used to regulate the amount of light received by plants in a southern exposure.

West-facing windows provide indirect light in the morning and early afternoon, but strong direct light and higher temperatures in mid- to late afternoon. Plants that need either direct light or bright, indirect light would do well in front of or near a west-facing window.

Many plants do well under fluorescent lights, but the lights must be close (within a few inches of the plant) to produce good growth. Fluorescent lighting is best used on a limited basis, such as a light fixture placed near an African violet to promote bloom, or a fixture placed over a terrarium. Regular fluorescent tubes are fine for plant growth, there is no need to buy expensive "grow lights.”

Incandescent lights do not produce the right spectrum of light for plant growth and they produce more heat than light. Do not use them near plants.

There are signs to look for which indicate that a plant is receiving too much light or too little. Plants that are receiving too little light may have stretched or leggy growth, abnormally small leaves, or a yellowish-green color. Flowering plant may not flower when light levels are too low. Plants with variegated leaves may revert back to all green leaves under low light conditions.

Plants that are receiving too much light may have leaves that appear bleached or scorched. The leaves may also take on a pale yellow green color.

Humidity: Most houseplants prefer humidity levels between 40 and 60 percent. Heating the home in winter can lead to lower levels of humidity. There are ways to increase humidity around plants. A room humidifier would provide increased humidity for the entire room, making it more comfortable for plants and people alike.

Grouping plants together will help raise humidity in the vicinity of the plants. Plants give off moisture through their leaves. Grouping the plants together allows the plants to benefit from this evaporation. To increase the humidity even more, place the grouping of plants on a pebble tray. A pebble tray is a shallow tray fill with pebbles or gravel. The pebbles are moistened and as water evaporates, the humidity is raised. The level of the water on the tray should be below the house plant's pot, so that the plants is not receiving excess water. Misting by hand is not recommended as the amount of humidity produced is very small and short-lived.

Temperature: Most houseplants are tropical or subtropical in nature and thus must have temperatures above 55°F. Temperatures below 55°F may cause houseplant leaves to droop. As a rule of thumb, foliage plants prefer temperatures between 65 and 75°F. Flowering houseplants prefer 65-75°F during the day and 55-60°F at night. Very high temperatures can be detrimental to all houseplants.

Basic House Plant Care

Watering: There is no magic formula or timetable for watering houseplants. Since temperatures, light and humidity tend to change, it is not practical to water houseplants on a set schedule. The best way to tell if a plant needs water is to feel the soil and see how dry it is. When the top inch of soil is dry, it is time to water.

Top watering and bottom watering are both acceptable methods. With bottom watering, salts may accumulate in the soil and need to be flushed out from the top periodically. When watering from the top, apply water until it comes out the drainage hole. Let the plant sit in the water in the saucer about 15 minutes, then drain off the excess water. When watering from the top, be sure to apply the water evenly to the soil surface. If all the water is applied in one spot, a "pipeline" might develop and water will flow through without wetting the soil.

Fertilizing: There are several types of fertilizer specially formulated for houseplants. They may be liquids, powders intended to be dissolved in water or slow release products (beads or sticks) to be placed in the soil.

Most houseplants do not need much fertilizer. The best time to fertilizer is when the plant is actively growing. During the winter, houseplants are not growing much and should not be fertilized. As the days grow longer, growth resumes and fertilizer may be applied. Usually fertilizing every 4-6 weeks is adequate. Be sure to follow the directions on the fertilizer package.

Two cautions on fertilizing:

  1. Fertilizer will not compensate for poor growing conditions
  2. Fertilizer should not be applied to a wilted or dry plant; it needs water, not fertilizer.

December - January 2003: Stacking Up Firewood for Winter | House Plant Care | Holiday Legends | Winter Injury on Arborvitae

 

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