Garden Journal

Clean House with Tropical Plants

Doreen G. Howard

NASA calls it Sick Building Syndrome. I know it as a stuffy house that needs a good airing, as my Mom put it. By the end of January, if it weren’t for the forest of houseplants in my home, I’d open the windows, despite the snow and freezing daytime temperatures. I did open them before I learned that tropical houseplants clean indoor air of pollution.

Houseplants help rid the home of toxins such as benzene, formaldehyde, carbon dioxide and trichloroethylene, all chemicals that off-gas from man-made materials used to build and insulate a home. They can cause leukemia, liver disease and a myriad of cancers. Unfortunately, no houseplant rids the air of tobacco smoke. 

The NASA studies on indoor pollution done in 1989 recommends 15 to 18 plants in 6 to 8-inch- diameter containers to clean the air in an average 1,800 square foot house. That’s roughly one plant per 100 square feet of floor space.

Most of the plants that remove pollutants, scientists found, come from tropical forests where they only get light filtered through the branches of taller trees. Their leaf composition lets them photosynthesize and move air efficiently in low light conditions of the average home.

Soil and roots also remove air-borne pollution. Bacteria and fungi in soil use pollutants as a food source to feed plant roots. If you remove lower leaves on plants to expose as much soil as possible, even more toxins are absorbed to feed plants. Don’t use the picked leaves to make a salad or compost them! Dispose of the leaves safely.

Common houseplants are the most efficient, NASA found. Some of my favorites like sansevieria, Lady palm and heartleaf philodendron are on the space agency’s top plants list. My hanging basket of philodendron crawls and snakes all over the windows, to the ceiling, in the sunroom. It verges on being a weed, but a weed that does an excellent job in keeping that room fresh.

Take a look at NASA Top 15 Plant List below. Add a few to your collection or buy a dozen to get started, knowing you are cleaning house sustainably. How green is that?

English ivy
Spider plant
Spathiphyllum (Peace lily)
Aglaonema (Chinese evergreen)
Bamboo, Lady or Reed palms
Sansevieria (Snake plant)
Heartleaf philodendron
Selloum or tree philodendron
Elephant ear philodendron
Golden pothos
Dracaena marginata (red-edged)
Cornstalk dracaena (also called Magic bamboo)
‘Janet Craig’ dracaena
Dracaena ‘Warneckii’
Ficus Benjamin (weeping fig)

To share your thoughts, questions, and tips, just post a comment in the box below. We'd like to know what you think!


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By Janet February 6, 2009 -

By Janet February 6, 2009 - 5:22 pmA lot of people dont relaly think about it but it is important. My sister had a dog that nearly died from eating on some of her houseplants. Now she (as well as I) is very careful about what plants she keeps around.

Which plants on the list are

Which plants on the list are known to be nontoxic? I have a toddler & have heard a lot of house plants are toxic if accidentally ingested. It's hard to keep all the plants up high. Thanks!

Stay away from the dracenas,

Stay away from the dracenas, and you'll be OK.

Hello! I have enjoyed your

Hello! I have enjoyed your article and helpful list; I too am on a mission to clean my indoor air. I have seen several sites indicate that dracenas are on the "safe-non-toxic" list for houseplants. Yours is the first time (and now I am further researching) I've seen an indication that my little dark green dracena might be a hazard to our 1.5yr old son that puts EVERYTHING in his mouth. Should I get rid of it? Hang it? Why am I now seeing conflicting information on this one? I am so glad I read your article to encourage me to do a bit more research on trusted plants. Thank you!

Some dracaena varieties have

Some dracaena varieties have a thick white fluid in their stems. If ingested, it causes itching, redness and mouth sore.

Re Poinsettias: I lose very

Re Poinsettias: I lose very few leaves and they still look nice after 2 months. The house is on the cool side (65F), so that helps, but I water only when the soil is dry to the touch. Usually it's every 2 weeks, but it's been nearly 3 weeks now. I take them to the sink, slowly pour in one quart of water, then a second quart, and let them drain for a few minutes.

For reflowering, you have to control how much light they get in the fall.

Houseplants and cats

Considering that most dracaena are poisonous to cats, I have to be picky about the plants I grow. Most on the list are toxic to animals. How do others deal with this problem?

2 questions

I'm trying to reflower my poinsettias from this past Christmas. I have an instruction sheet that I'm following. Right now I have 3 plants in front of my living room window for sun. I water them about once a week, full water and then drain them on towels for several hours. My question is that they are browning (more like black) around the edges of the leaves. I'm wondering if I'm giving them too much water even though I drain them well.

2nd question is about my daughters cactus's. She couldn't take them back to her college dorm this time and I have them in the same window for sun only off to the side so they're not getting much. They get watered about every other week. I just lost a 2nd one because it was completely rotted. I'm good with houseplants but not cactus's. Any advice?

Poinsettia & Cactus

Sounds like both plants aren't getting enough light.  They need south-facing windows or supplemental grow-lights.  Water cacti every 4-6 weeks.  In cooler weather, they are like camels, needing no water.  The fact that one cactus rotted shows it was getting too much water.

Thank you so much. I don't

Thank you so much. I don't know how much water my daughter had been giving the cacti but I only put on about 2 capfuls every other week. I'll wait a long while before watering again. I've been thinking about the grow light. The best sun comes in our patio room but we also have baseboard heating in there so can't keep anything too close to the windows. Been tried before and the plants don't like it. Thanks again for your help. Mary


I read somewhere of a gal who watched the Arizona weather and watered her cactus when Phoenix got rain. She claimed it to be succussful!

That sounds like a great

That sounds like a great idea! I may have to do that! These are just little tiny cactus's. The dog knocked a cushion into them and a few fell over and had to be repotted. I think that's also why we've had problems with them.

House Plants

I love having my house plants in my house. I have a problem with gnats in my house & plants. How do you get rid of them w/o throwing the plants out doors?


Mulch soil in containers with white sand or turkey grit.  Gnat eggs can't hatch in those.  You can buy turkey grit at farm stores.  It's also the perfect mulch for lavender plants.

Let the top of the soil dry

Let the top of the soil dry between waterings. Mulching with sand or gravel also works. If it's a thirsty plant you can use Bti (Bacillus thuringiensis subspecies Israelensis) which can be found at most hardware type big box stores in the insecticide section labeled Mosquito Beater "Plunks" or Mosquito Dunks. It's completely safe for indoors used as a soil drench.

plants are amazing

I have been growing plants including several of the tropicals mentioned for ages and always bring them inside for the winter where they brighten up those dreary winter days while helping to clean the air at the same time.


Just wish I knew of plants that would help with dust collection! I enjoy many house plants for their good benefits. Thanks for the reminder to not use dead leaves for muclh; had been doing that.

Sick Building Syndrome

Interesting article, Doreen. I knew there was a good reason, beyond their aesthetic beauty, I loved having houseplants scattered about the house!

sanke plant dying looks like rotting at base.

It was big and beautiful now dying inside the house. Not to much water giving. What can I do?

Not an expert but i suspect

Not an expert but i suspect it was over-watered and probably can't be saved.