INDOOR LANDSCAPING
by Jerry Parsons, Ph.D.
Horticulture Specialist, Texas Agricultural Extension Service in San Antonio

The first thing to consider in selecting a plant for interior decoration or indoor landscaping is the desired permanence.

Cut-flowers in an arrangement are temporary, while the majority of flowering plants in containers are used for a somewhat longer time, or until their blooming period is completed. Think of the plants you select for your interior as a fixture that is as much as the permanent décor as draperies or paintings. However, this comparison will have limitations since paintings and sculpture require no care, except occasional cleaning or dusting. However, indoor plants will grow larger and sometimes even outgrow their surroundings over time.

What are the qualities of a good plant for an interior landscape- First, it must be vigorous and strong, and be able to withstand more adverse conditions than the average outdoor plant. Indoor areas have more challenging conditions for excellent growth, such as minimum light and rather inadequate ventilation. Inside, night temperatures are warmer, there are drafts and the atmosphere is drier. While all of these environmental factors may be controlled to a certain extent, they're always present and eventually a delicate plant will succumb to these conditions.

The second important characteristic of a plant well suited for inside is that it should be evergreen, since it will be seen everyday throughout the entire year.

In addition to being evergreen and robust, plants selected for indoors must also be attractive. While most of these plants will flower from time to time, the major appearance considerations are directed toward the plant's foliage and how the plants grow. The leaves may be selected for their color or form, or both. The growth habit (form and shape) of these plants should be attractive and require the most minimum of maintenance.

Many plants suitable for indoors have variegated leaves. When these plants are selected, the inside light intensity must be greater than the light required for plants "plain" green leaves. Variegated foliage needs more light in order to retain its bright and striking color contrasts. The leaves of many tropical foliage plants specially adapted to indoor conditions can, of course, be very fascinating with no more color than the natural green color of their leaves. In many instances, the size, texture and surface of the foliage is its most attractive feature. Most plants that are best suited to indoor success thrive in medium- to low-light intensities.

For best results, select plants that are slow-growing. They will perform well over a longer period of time without a great deal of pruning or training. Some of the easiest house plants to grow include:

Heartleaf Philodendron: Philodendron oxycardium (cordatum). While most of the philodendrons are easy to grow, this is the easiest. The name Philodendron is derived from the Greek language and it means tree-loving. Therefore, it's not unusual to find climbing forms of Philodendron such as Heartleaf trained on "totem poles" made of bark or osmunda fiber.

Devil's Ivy: Scindapsus aureus. This plant looks a lot like a variegated Heartleaf Philodendron and, in fact, it is often called "Philodendron". To further confuse matters, it is also called Pothos. Whatever you call it, it is easy to grow. The best variety of scindapsus is 'Marble Queen'. Many times the leaves of this variety are so variegated that they are almost white. This variegation is more intense in good light.

Chinese Evergreen: Aglaonema commutatum. This is an excellent plant that is not used enough. Of all house plants, it is perhaps the easiest to grow and some of the newer varieties are very attractive. The standard Chinese Evergreen is a bit dull with green arrowhead-shaped leaves, but the variety 'Silver Queen' is striking.

'Janet Craig' Dracaena: Dracaena deremensis var. 'Janet Craig'. There are many dracaenas suitable for use in the home, but this is one of the best. All members of this genus may occasionally have dead, brown leaf tips due to low humidity. However, on 'Janet Craig' it is not that noticeable. This plant may even be tougher than the Chinese Evergreen.

Spathiphyllum: This is the so-called "closet plant" that is very tolerant of low-light indoor conditions, even though it will not grow in a closet!

Arrowhead Plant: Syngonium or Nephthytis. It's a tough plant with both green and variegated forms available

Cacti and Succulents, such as Aloe and Euphorbia are fine if you have lots of light.

Wax Plant or Hoya is a very durable, vining plant.

"Red Bird": Pedilanthus is a waxy, variegated plant.

Swedish Ivy: Plectranthus is an apple-green plant that makes a nice hanging basket

Don't forget to dust and prune your house plants during the summer months. In the winter, dust from the heating system can coat the leaves, clogging the pores (stomata) through which the leaves breathe. In the summer, when windows are open, there is even more dust in the air to collect on plant leaves.

Dust can be removed in several ways. A damp, soft cloth or sponge is good for plants with large leaves. Ordinary tissue will also do, but be gentle so as not to bruise the leaves. Another method is to mist plants, or give them a tepid shower in the bathtub or sink. To prevent soil from washing out of the pot, wrap a piece of plastic around the base of the plant and pot.

Pruning is also a good idea. It keeps the plant at the size desired and improves its shape. Remove the browned tips of leaves or leaves that are yellowing. These can occur even on healthy plants, primarily in the winter. Plants with thin, sharp tips such as Dracaena, spider plant, aspidistra and ferns suffer most. When the edges of leaves turn brown, snip them, following the shape of the leaf and repeating as often as necessary. Water plants when needed. The leading cause of most house plants deaths is over-watering. Simply check the plant weekly by using the most tried-and-proven technique-- the finger test. Simply place your index finger knuckle- deep into the potting soil. If you feel moisture --DON'T WATER! But if the mix is dry, completely saturate the potting soil.

House plants also respond to soil aeration. Loosen the soil with a kitchen fork to help the roots get air. This also helps to get rid of the mold that sometimes collects on the surface of the soil when plants are kept too moist or in poor light. A generally recommended feeding program includes using a water-soluble fertilizer once every 6 weeks, as well as a slow release fertilizer (Osmocote) every 6 months as a top dressing in the pot, or mixed into the potting soil when plants are transplanted into larger pots.

Occasionally, house plants may suffer insect problems. Controlling insects such as aphids, mealybugs or spidermites may seem to be a never ending battle, but the use of a systemic insecticide containing Di-Syston granules as a preventative measure will help. Follow the product label directions and cautions.

Sometimes people think that living house plants are not worth all the bother. Think again. The use of non-biodegradable plastic plants defeats the whole goal of beautification. It adds to pollution. The only difference between a plastic plant and a plastic carton is size. Real IS best!

For much more information about interiorscape plants, see:

http://aggie-horticulture.tamu.edu/interiorscape

House Plant Care

The most frequently asked question about house plants is "Why does the bottom foliage of my houseplants turn yellow and then drop?" There is no concrete answer. Leaf drop associated with plants is usually due to improper growing conditions.

The cause may be one or a combination of factors. In all, there are about 10 common causes of leaf drop.

The first is improper light. Insufficient natural light or perhaps too light intensity that is two great, possibly causing scorching and then eventually, leaf drop. This may be particularly true in plants of the Ficus Family.

The second cause of leaf drop is shock at transplanting. Transplanting will ultimately lead to stress and stress leads to shock.

The third cause is a sudden change in temperature or light, which also causes shock. Always be familiar with the light requirements of your plants and try not to make changes. Most sudden changes in temperature and/or light occur when we move plants from indoors to outdoors or vice versa.

The fourth cause is too much fertilizer. We seem to live with the idea that a little will do a little good and a lot will do a lot of good. This is just not so when it comes to fertilizing. Seldom will under-fertilization lead to leaf drop.

Drafty locations will be the fifth cause of leaf drop. Therefore, placing them under or around air conditioning and heating vents should be avoided.

Sixth is gas fumes. Leaky space heaters or stoves using natural gas, butane or propane can also cause severe leaf drop in ferns. Also, severe infestations of insects and diseases may cause leaf drop if allowed to spread uncontrollably. Check plants frequently for insects and diseases and treat promptly if needed.

Packed soil due to infrequent repotting and improper watering may lead to leaf drop. In this case, leaf drop may be the result of a lack of oxygen. Repotting will help correct this problem.

Finally, the tenth cause of leaf drop is moisture fluxuations. This can easily be corrected by following a schedule of frequent, light applications of water.

There are a number of insects that attack our house plants. Many times we bring them in when we move our plants indoors after repotting, watering, or airing-out period outdoors. Just about all of the common houseplant insects are sucking types. These include mealybugs, spider mites, aphids and scale insects.

Mealybugs are soft-bodied, oval insects with well-developed legs and segmented bodies that are covered with powdery wax. Many mealybug species have flat bodies with pointed sides and tail-like filaments. The adults and the nymphs feed in compact groups. They suck juices from leaves, stems and roots of our house plants. Mealybugs may be controlled using diazinon or Malathion with 1/4 teaspoon of a liquid dish-washing soap, or, you might like to try the insecticidal soaps now on the market for control of mealybugs.

Spider mites, which include the 2-spotted spider mites and red spider mites, are some of the most destructive pests of indoor plants. These tiny bugs feed underneath the leaves and are known for spinning fine webs along veins and leaves. They are considered sucking insects and in severe cases can cause chlorosis and stunting, eventually leading to death. For control, 2 chemicals are widely used for severe cases, Malathion and Kelthane. Kelthane is a miticide and may be most effective. Before applying these or any chemical, read the directions for specific instructions. Where spider mite infestations are not too severe, insecticidal soap and water may be used to eradicate or retard infestations. To use soap and water, take the plant outside and cover the container with aluminum foil to keep from losing the soil. Turn the plant to its side and, using a sprayer ,thoroughly apply the soapy solution to the underside of the leaves. Afterwards, wash with clean water. See your local garden center for more detail on insecticidal soaps.

Aphids and scale are 2 additional insects that plague indoor houseplants. Aphids are commonly greenish-white but may also be brown, red or black. They are sucking insects and are normally found on the undersides of leaves and tips and shoots of young tender plants. They can cause chlorosis and stunting and may even lead to leaf drop and death of the plants.

Scale insects are also sucking insects and are found on nearly every part of the plant. Young, immature scales in the "crawler" stage are found on the underside of leaves and the tips of plants. As they mature and become stationary with their waxy coat, they are normally found on older leaves and stems. Control of both aphids and scale include using insecticidal soaps, Malathion, diazinon and pyrethrins.

Always treat plants outdoors and then bring them in after the chemical has dried. Treat all plants including the soil before they are brought in for the winter, and check the undersides of pots and trays for centipedes, millipedes, snails, slugs, sowbugs, and pillbugs that may be harboring underneath.