By Melanie Mathieson
The Gardening Guru
Light, temperature, humidity, and ventilation are chief home environmental factors affecting plant growth. Any one of these factors in incorrect proportions will prevent proper plant growth indoors.
Before purchasing any house plant, you need to do your research and take a look at your home and its environmental conditions before you purchase.
Light is probably the most essential factor for house plant growth. The growth of plants and the length of time they remain active depend on the amount of light they receive.
Light is necessary for all plants because they use this energy source to photosynthesize.
When examining light levels for any house plant, consider the three aspects of light in the area you are placing the plant— intensity, duration, and quality.
Light intensity influences flowering, stem length, leaf colour, and the manufacture of plant food. For example, a geranium grown in low light tends to be spindly and the leaves light green in colour.
A similar plant grown in very bright light would tend to be shorter, better branched, and have larger, dark green leaves.
House plants can be classified according to their light needs, such as high, medium, and low light requirements. The intensity of light a plant receives indoors depends upon the nearness of the light source to the plant (light intensity decreases rapidly as you move away from the source).
The direction the windows in your home face will affect the intensity of natural sunlight that plants receive. Southern exposures have the most intense light, eastern and western exposures receive about 60 percent of the intensity of southern exposures, and northern exposures receive 20 percent of a southern exposure.
A southern exposure is the warmest, eastern and western are less warm, and a northern exposure is the coolest.
Other factors which can influence the intensity of light penetrating a window are the presence of curtains, trees outside the window, weather, seasons of the year, shade from other buildings, and the cleanliness of the window.
Reflective, light-coloured surfaces inside the home will increase the intensity of light available to plants. Dark surfaces will decrease light intensity.
Excessive light is as harmful as too little light. When a plant gets too much direct light, the leaves become pale, sometimes sunburn, turn brown, and die. Therefore, during the summer months, protect plants from too much direct sunlight.
Day-length or duration of light received by plants also is of some importance, but generally only to those house plants which are photosensitive.
For example, Poinsettia, Kalanchoe, and Christmas cactus bud and flower only when day-length is short (11 hours of daylight or less). For the most part, most flowering house plants are indifferent to day-length.
Most house plants tolerate normal temperature fluctuations. In general, foliage house plants grow best in temperatures between 70 and 80 degrees F during the day and from 60-68 degrees F at night.
Most flowering house plants prefer the same daytime range but grow best at when night temperatures range from 55-60 degrees F. The lower night temperature induces physiological recovery from moisture loss, intensifies flower colour, and prolongs flower life.
Excessively low or high temperatures may cause plant failures, stop growth, or cause spindly appearance and foliage damage or drop. A cooler temperature at night actually is more desirable for plant growth than higher temperatures.
A good rule of thumb is to keep the night temperature 10-15 degrees lower then the day temperature.
Atmospheric humidity is expressed as a percentage of the moisture saturation of air.
Two ways to provide increased humidity are by attaching a humidifier to the heating or ventilating system in the home or placing gravel trays (in which an even moisture level is maintained) under the flower pots or containers.
This will increase the relative humidity in the vicinity of the containers. As the moisture around the pebbles evaporates, the relative humidity is raised.
Another way to raise humidity is to group plants close together. You also can spray a fine mist on the foliage early in the day so that the plants will be dry by night.
This lessens the chance of disease since cool dampness at night provides an ideal environment for disease infection.
House plants, especially flowering varieties, are very sensitive to drafts or heat from registers. Forced air dries the plants rapidly, overtaxes their limited root systems, and may cause damage or plant loss.
Now that you have assessed your home and the different locations where you may plan to add some house plants, you can use this knowledge to purchase plants best suited to your home conditions.
By doing a little bit of homework first, you will increase your chances for long-term success in growing house plants.