House Plants to Clean Indoor Air

• Notes made in 2006, reasonably complete information, sources could have been retained better.
• Uhg! Just realized there's statements about using Malathion, Diazinon, etc. Short edit: Don't! Use something natural. Eventually I'll go back trhough this and edit out the bad crap.
• Important!: If you're going to do any re-potting or soil work, see the Terra Preta document. Google Terra Preta for background info.
• Michael.

• The recommendation is one 6 inch plant per 100 square feet of interior.
• One average-size plant can help purify up to 100 cubic feet of air

(Not sure if that second one is suppose to be 1,000 cubic feet, 10x10x10, as with an 8 foot ceiling for 100 cubic feet you'd need a plant for every 3.5 x 3.5 feet?)

• If the light conditions are very low, philodendron and other plants like it will produce more oxygen.
• Spiderplant, best at removing gaseous pollutants such as formaldehyde
• Plants with fuzzy leaves were best at removing particulate pollutants such as smoke and grease particles.
• Some that are relatively maintenance-free are Aloes, Cactus, Spider Plants, Pothos, and Dracaenas.

Pictures of many:
http://www.paradisedesigns.com/plants.html

More of a list (Easy to Hard):
http://redwoodbarn.com/DE_houseplants.html

TOP 10 plants most effective in removing:
formaldehyde, benzene, and carbon monoxide from the air.

Plants for Fresh Air
Most green house plants will clean up a variety of pollutants in your home or office. Spider plants and heartleaf philodendron are good at removing formaldehyde from your air (from carpeting, fiberboard, plywood, resins, and natural gas). Also effective at this are azaleas, mother-in-law's tongue, poinsettias, and ficus. English ivy, marginata, and golden pothos combat benzene (found in tobacco smoke, synthetic fibers, plastics, and detergents). Peace lilies and dragon trees can clear up TCE (from paints, varnishes, and wood finishes). So surround yourself with these plants and others for healthier air where you live.

* Areca Palm [LOW LIGHT](with the highest rating of 8.5) "is consistently rated among the best houseplants for removing all indoor air toxins tested. It also has the unique ability to move salt accumulations to selected branches. Its high marks in all rated categories make the areca one of the top 'eco-friendly' houseplants."

* Lady Palm (also 8.5) "is one of the easiest houseplants to care for and is highly resistant to attack by most plant insects. It is also one of the best plants for improving indoor air quality."

* Bamboo Palm (8.4) "pumps much needed moisture into the indoor atmosphere, especially during winter months when heating systems dry the air.This palm is also one of the top-rated plants tested for the removal of benzene, trichloroethylene and formaldehyde."

* Boston Fern (7.5) "is the best [of the plants tested] for removing air pollutants, especially formaldehyde, and for adding humidity to the indoor environment."

* Snake Plant [LOW LIGHT](6.3) "is almost indestructible. The snake plant differs from most houseplants in that it produces oxygen and removes carbon dioxide at night."

Heartleaf Philodendron: [LOW LIGHT]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: [LOW LIGHT]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.