Houseplants can be a beautiful and healthful addition to almost any home. The right plants for the right space not only enhance the ambience, but help filter the stale air that normally develops when a home is closed up for the winter or in summer when the air conditioner is running.
The first consideration for owning plants is choosing them from a reputable greenhouse or nursery. The plants selected should fit the lifestyle of the owner. Knowledgeable greenhouse personnel can advise you in selecting the best ones for your lifestyle. If you travel a great deal, you may need someone to look after your plants while you are away.
When making your initial purchases, do be picky. Insist on plants that:
• Are free of insects and diseases,
• Are sturdy, clean, and well potted,
• Have healthy foliage,
• Do not have yellow or chloritic leaves,
• Do not have brown leaf margins,
• Are not wilted, and
• Do not have spots or blotches. Remember you really don’t want to buy diseased or insect-infested plants; if you take them home and you have other indoor plants, these can quickly spread.
• Avoid those with spindly growth.
• Also, consider the environmental conditions of your home
When you do buy plants, remember, transporting them correctly is very important. When moving them to your home, be aware of the two seasons of the year that can cause the most damage.
• Summer has high temperatures that can insure some plants, and they can be burned by direct exposure to sun. So, don't forget to shade your plants from direct sun.
• In winter, always wrap plants thoroughly with newspaper or paper bags before taking outside. And remember, automobile trunks are too cold, so place newly purchased plants in front and turn on the heater. Do not allow wind to blow across them through open windows.
After you have gotten your plants home safely, the acclimatization process should begin. Plants that require full sun should gradually be moved into a sunny location. Plants that require shade can be moved into the ideal location right away. The location of indoor plants can best be determined by the type of plant purchased.
Factors affecting indoor plant growth include:
• light
• water
• temperature
• humidity
• ventilation
• fertilization
• soil
Light, the most essential factor in plant growth, is used for photo-synthesization. Light level aspects to consider are intensity, duration and quality.
Light intensity influences the manufacturing of plant food, stem length, leaf color, and flowering. Plants are classified into three light intensity categories – high, medium, and low.
Remember that light intensity decreases as you move away from the light source. A window facing south offers the most intense and warmest light. Eastern and western exposures offer only 60% of southern exposure intensity. Northern exposure offers only 20% of southern exposure intensity.
Other factors that directly affect light intensity are:
• curtains over or around windows
• trees or shrubs outside the window
• weather
• season
• shade from adjacent buildings
• cleanliness of window
• reflective (light-colored) surfaces
• dark surfaces
The duration of light also has a direct effect on your plants. Day length naturally varies during winter months. Such plants as poinsettia and Christmas cactus will only bud or flower with 11 hours or less light. Low intensity light can be increased by duration.
Please note that while light is essential to plants, excessive light can also cause problems such as pale leaves and burned and/or browning leaves.
The quality of light is another topic for consideration.
Incandescent light is mostly red, with some infrared, and is low in blues. Fluorescent varies according to the amount of phosphorus contained in the bulbs, but primarily contains cool-white, has mostly blues and is low in red. Plants grow best in incandescent light, although photosynthesis requires blues and reds, and flowering requires infrared.
When you water, do so evenly around your plants. That is, don’t just water one side, because the entire container requires water. As we cannot use a set schedule for watering, it can be a tricky procedure. Some plants thrive in drier conditions while others do not. The potting medium and environmental conditions in your home are important considerations. Plant roots are generally located in the bottom 2/3 of the pot. It is best to feel the soil – for a 6” pot push your index finger 2” into the soil; if it moist, do not water.
If your houseplants begin to exhibit a layer of white on the surface of the potting mix and around the pot, this is a build up of soluble salts from watering. To help eliminate these, just take the pot to a basin or outdoors, if weather permits, and pour enough water through the potting medium to flush out the salt residue. This procedure also assures you that the roots in the bottom of the pot have been thoroughly watered.
Houseplants generally can tolerate fluctuations of temperature. Normally, the temperature for foliage plants during the day should be maintained between 70 and 80 degrees F. At night, most plants can tolerate a decrease of between 10–15 degrees (60-68 degrees F.). For flowering plants a temperature between 70 and 80 F. degrees during the day and 55-60 F. degrees at night induces physiological recovery from loss of moisture, intensifies flower color, and prolongs flower life.
Extreme temperature fluctuations – excessively high or low - can cause plant failure, stop normal growth, cause a spindly appearance and foliage damage or drop.
Humidity is the percentage of moisture in the air. To increase humidity in your home you can add a humidifier to the heating or ventilation system, or place trays containing gravel and water under plant containers. As the moisture evaporates the humidity level will rise. Always be cautious that the bottom of the plant pot does not come into contact with the water in the tray, as this could lead to plant damage.
Proper ventilation can be a big problem for plants. Some are naturally draft sensitive, while others can tolerate wide fluctuations. Forced air from your furnace can dry plants rapidly, overtax limited root systems, and, in some cases, can cause plant loss. Additionally, some houseplants are naturally sensitive to natural or blended gas (Note: blended gas has proven more toxic). Fumes from these can cause plants to refuse to flower and to drop flower buds and/or foliage.
Fertilizers for indoor plants are sold in granular, crystalline, liquid, or tablet forms. Always read the label before purchasing fertilizer. The three necessary ingredients are nitrogen (N), phosphorus (P), and potassium (K). They come in dozens of combinations and many companies manufacture them. Always use fertilizer according to the package directions. The specific needs of plants differ according to their size, rate of growth and age. As a general rule, fertilize every two weeks from March to September.
During the winter months, no fertilizer is needed because reduced light and temperature result in reduced growth. Fertilizing at this time could be detrimental to some plants.
The potting soil or growing medium for plants should be of good quality. Most of the artificial mixes sold today actually contain no soil. Many high quality mixes now come fortified with slow-release fertilizers. This addition takes care of the need to fertilize plants for several months. Although commercial mixes are handy to use, they don’t always prove the best for the health of plants. If possible, it is best to mix your own.
Making your own artificial potting mix is a fairly simple task. You will need organic matter (peat moss or ground pine bark) and inorganic material(washed sand, vermiculite or perlite). A formula used in the Master Gardener instructions follows:
1 bushel shredded peat moss
2 bushels perlite or vermiculite
½ cup finely ground agricultural lime
1/3 cup 20% super phosphate
½ cup 8-8-8 or similar analysis mixed fertilizer
1 level teaspoon chelated iron
When it comes to containers, there are many different products from which to choose. Many kinds of stores sell containers, and the price range varies from less than a dollar to several hundred. Some options are ceramic, plastic, fiberglass, wood, aluminum, copper, and brass.
Clay containers, though once extremely popular, tend to absorb and lose water through their walls. The largest number of plant roots tends to grow near these very walls and, therefore, not all plants do well in such containers. Clay containers do provide an excellent source of aeration.
Ceramic containers were once also very popular houseplant containers. However, many are designed without drainage holes and can create a problem with plants that do not like wet feet (having their roots wet most of the time). If ceramic containers are used, the plant owner should water carefully. For the most part, they should be avoided since, even with pot chips or gravel added to the potting medium, soil drainage cannot be improved when there is no drainage hole. A plant lover can double pot; that is, use a ceramic pot with a smaller size pot inside. This way, when watering, the smaller pot with the plant inside can be removed and the watering completed without fear of over watering.
Plastic and fiberglass containers have become very popular over the last few years. They are light and easy to handle, usually inexpensive, much easier to sterilize and clean than the old-style terra cotta pots, need less watering, and have a tendency to accumulate fewer salts.
Training and grooming your indoor plants is also important. Simple activities such as dusting the leaves and removing all spent flowers help keep plants looking good and decrease the opportunity for disease and insects. Pinching, or the removal of 1” or less of new stem or leaf growth just above the node, stimulates new growth. Pruning parts other than terminal shoot tips can help shape your plants and keep them growing vigorously. Disbudding (clipping or removing flower buds) is normally done to obtain larger blooms and to prevent flowering of very young plants or recently rooted cuttings. This can result in sturdier plants and allow them to acclimate to their surroundings before putting forth the effort required to produce flowers.
In summation, indoor plants are beautiful and enjoyable when we take the time to treat them well. Always remember to consider your personal lifestyle in selecting quality plants from a knowledgeable nursery or greenhouse operator.
Happy Indoor gardening!
Excerpts were taken from the presentation of Extension Agent Melanie W. Barrows to the HOVMG students in 2004 and the Master Gardener Handbook (2004).
Written by members of the Heart of Virginia Master Gardeners
posted 3/1/07