Tuesday, August 5, 2014

Areca Palm (Chrysalidocarpus lutescens): Best Air Cleaning Plant #2

The Areca Palm goes by a number of names: yellow palm, the butterfly palm. bamboo palm, or golden cane palm. It's native to Madagascar, where it grows in tropical rain forests or near moist river beds. It has since been naturalized to a number of islands near Africa, the Carribean, and Central and South America, basically any region that's tropical or subtropical and humid. And of course, it's one of the most popular houseplants in the world.

The Areca Palm is the only plant on Dr. Wolverton's list that gets a 10 out of 10 for transpiration--the rate at which it releases moisture back into the air. In fact, a 6 foot areca palm can release about one whole quart of water into the air every 24 hours, making it a great natural humidifier. Of course, this water has to come from somewhere, which means keeping watering it a LOT. You need to keep the root ball ball damp, mist regularly (at least daily), and provide humidity as much as you can, especially in a dry office or home environment (for example, putting it in a subirrigation planter or placing the planter on a bowl of rocks with water).

Ironically, while I talked earlier about how overwatering plants can cause excessive soil mites and fungus gnats, underwatering the areca palm can have the same effect, attracting nasties like spider mites, which thrive under hot, dry conditions.

Of course I can't talk about plants I buy at Kmart without finding something to complain about. And in this case, when I brought the Palm home I first notice a couple scale insects on the leaves (one pest I haven't had to deal with so far), which I immediately plucked off the plan. Luckily, it didn't look like an infestation, probably just a few that migrated over from neighboring plants. Again, great job by the Kmart in Manhattan.

After I got home, I noticed "freckles" (or if you prefer, "speckles" or "spots") all over the stems. Weirder still, I found that if I wiped them with a wet and slightly abrasive cloth (like a paper towel) they'd come right off.


I was perplexed as to what these were. I Googled it, and while I found a few others who encountered the same thing, no one seemed to know what they were. The one thing I learned is that people on the Internet love to talk about stuff they know nothing about. Some people swore these were more scale insects, but after a slight moment of panic I discounter this because they simply don't have the icky "bump" you generally see with scale. Others speculated that it's something called "flyspeck fungus". Some websites report that if you see spotting or speckling on leaves (but they didn't mention stems) it's an indication that there were salts or minerals in the water, as Arecas have the ability to move salt accumulations to selected branches (when the branches get saturated they'll die and you need to remove them, but the damage will be isolated to that frond). And others said this is just a natural phenomenon that happens with all Arecas. 

Just to be safe, I took a paper towel and some dish soap and scrubbed each of the stems. There's still spotting on them but it's a lot less than before.

I brought the plant to the office. Here's what it looks like right now: 



Arecas like indirect light, as direct sunlight can easily burn the leaves. I do have a corner of my office window that never gets direct sunlight, so I'll leave it there for a while. It helps that I have access to spring water outside my office, so I'll use that to water the plant to prevent it from having to deal with things like fluoride and salts in tap water.

My next step is going to be to repot it; while Arecas are okay being pot-bound, the current pot is too small for it to grow from its current height of about 2 feet to its standard indoor size of 6-8 feet (outdoors it can grow to 25 feet). This would require a pot that's about double what I have now.

As for the air-cleaning properties of the plant, this one ranks near the top. It removes benzene, formaldehyde, and trichloroethylene from the air.

Some care tips:

1) Temperature: Keep between 65-75 degrees Fahrenheit.
2) Sunlight: As much light as it can get without getting direct sunlight. 
3) Care and feeding: Keep the root ball damp but avoid having the pot sit in water, which can cause root rot. Mist frequently to keep a good appearance. keep spider mites away, and give it the humidity it craves and will pay back in the form of great transpiration. 





Thursday, July 31, 2014

Dracena "Janet Craig" (dracena deremensis "Janet Craig"): Best Air Cleaning Plant #13

As much as I hate Kmart for the fungus gnat infestations, I do like the fact that they keep sending me free money to use. And so, with the proper precautions, I'll still buy houseplants from them.

I was surprised to see a Dracena "Janet Craig" among the plants they were selling. Of all the Dracenas, this is the one that Dr. Wolverton identified as the best of the best in the dracaena fragrans family for clearing the air, and one of the best plants overall for removing trichloroethylene (TCH). It made it to #13 of my edited list of best air-cleaning plants.



The plant is beautiful, with shiny dark leaves that look much richer and fuller than its close relative the Warneckii (both are cultivars from Dracaena fragrans). There are varying opinions about its origin; some say it comes from Puerto Rico, while others say that it's from the Canary Islands, Africa, Asia, or Madagascar.



It's said to be a very forgiving plant, able to tolerate neglect and low lighting conditions. This particular variety is the "comapacta", which reaches a height of only 1 to 3 feet and grows slower than the regular variety.

If you had to choose just one dracena variety for air purification, this is the one to get. Since they're really popular you can usually find them at places like Home Depot, or find one on eBay.

The last question I have about this plant is--who exactly was Janet Craig? I dug and dug for this answer, but can't find it anywhere. What I did find was that this cultivar was patented on December 27, 1999 and that the inventor's name is James E. Shank, and the plant was discovered in 1995 in Costa Rica, growing on an ornamental plant farm.  I didn't even realize that plant varieties could be patented, nor that it was just 16 years ago that this plant first came onto the market--and has since become one of the most popular houseplants around. "Her" full name according to the patent is "Janet Craig Gomezzi", but there's no indication of who this was; my guess is that it was just a personal friend of the inventor. But whoever she is or was, she'll live on forever now through the thousands of these houseplants scattered around the world--and in my office window.

Some care tips:

1) Temperature: Keep between 60-80 degrees Fahrenheit.
2) Sunlight: It likes partial shade or shade. Medium indirect lighting is best. 
3) Care and feeding: Keep soil evenly moist but not soggy, and don't let the root ball dry. Feed every two weeks in the spring and summer. Water less often in the winter and wipe off leaves when they get dustry. 

Tuesday, July 29, 2014

Getting rid of Fungus Gnats with Drying Out Soil, Cinnamon, Sticky Traps, and Nematodes

Rainman was right. Kmart sucks. At least the Kmart in New York City at 34th Avenue sucks.

For those of you who are used to beautiful, bright Kmarts, this one happens to be in the lower LIRR levels of Penn Station in Manhattan, whose three levels are sort of like Dante's first three levels of hell. Products strewn all over the place, customers with sour looks on their faces and employees who clearly would rather be doing anything else but helping you (the nice young gentleman in the camera department being the exception).

As you know, I've been buying a lot of plants at that Kmart, mostly because they keep giving me free points and I figure, instead of using them to buy junk food I'll use them to rescue the poor, dying houseplants they have in 4" pots and give them a little love, Charlie Brown-style.

A few months ago I bought a big bag of potting soil from them and put it into a corner without thinking. Within a few days, I started noticing tiny flies all around the house. I Googled it, and realized they're fungus gnats. I looked all over for where they might be breeding, and finally stumbled upon that bag of soil in the corner (which I hadn't even opened). But out of tiny holes in the bag little fungus gnats were flying in and out, like some kind of high-rise gnat apartment.

The funny thing is, I searched on Google on how to get rid of fungus gnats, and stumbled upon this post I wrote in 2010 that talked about how to get rid of them.

Now just to recap, fungus gnats aren't tiny flies, they're not mosquitoes (even though they kind of look like miniature versions of them), and they're not fruit flies. They don't bite, they just get really, really annoying. They have a tendency to fly into your face and up your nose because they're attracted to the carbon dioxide you like to breathe out.

The fungus gnats' name sounds a little nastier than it really is. They don't spread fungus, they just like to eat it. They look for it in decaying plant matter and potting soil, including the aforementioned bag of soil from Kmart. And months after getting rid of the bag, I still see them, as they managed to fly their way into a couple of my plants, including a Corn Plant that I'll be writing about shortly.

As for my office, as you know I bought a whole bunch of plants from this same Kmart. Both the Golden Pothos and Warneckii you've already seen came from there, as did a few other plants I bought and haven't posted about yet. Nearly all of these plants, I found, came infested with fungus gnats. Seems that if you're a fungus gnat, 250 West 34th is like Studio 54 for gnats--they're snorting fungi, they're fooling around and having babies. They say a gnat can lay 200-300 eggs at a time, which is why getting rid of them can be a major pain. The only saving grace of gnats is that they don't have a very long lifespan. As larvae (when they actually can do the most damage to your plant roots) they develop for 2-3 weeks on or near the surface of your plants, and they live for 7-10 days as adults. The problem comes when you have hundreds of them flying from plant to plant raising multiple overlapping generations at a time.

So following my own advice from 2010, I did the following

1) I stopped watering all my plants, at home and in the office, until at least the top layer of soil was completely dry to the touch. Now most of these plants are pretty hardy and are known to withstand large periods of drought in the wild, so most of them are okay. But sadly, one of the plants I bought was a small 4 inch Boston fern, and ferns love moisture. I'd hoped to nurse it into a giant plant, but it looks like the gnats may be winning this one.



The browning of the leaves indicates two things--that larvae have infested the root system and are eating away at them until they rot, and that my holding off on water isn't helping the plant any. The problem is, if the eggs and larvae are in the roots, watering the plant won't do anything to kill them, but if I let the roots dry out, the plant will not survive. So I'm playing a bit of a balancing act to try to find the right timing where I can kill the gnat larvae and not be too late to water and mist the plant again. We'll see if the little fern pulls through...hang on little buddy.

2) I placed yellow sticky-fly traps all over the place both at home and in the office. I knew which plants at the office here infested, but at home I placed traps in multiple plants to see where they were breeding the most. I read a great piece of advice on the Web that said that you should place trap vertically to catch flying ones, but also horizontally over the soil that catch youngsters as they hatch and fly into the world for the first time (seems kind of cruel, but hey, their mama shouldn't have picked indoor houseplants as her maternity ward).

The advice turned out to be great as far as determining the source of the infestation--one morning I woke up and while the vertical fly trap had one or two gnats, the horizontal one over the corn plant at home had about half a dozen. It's not surprising to me because I tend to overwater that plant and the root system doesn't seem to suck in water as much as it does with my other plants, so the soil stays damp for a long time. At work, the culprit was the Dracaena Warneckii, so I segregated that plant from the rest of them.

Then one morning on both plants, those same fly traps had DOZENs. Warning--the next few pictures are not for the faint of heart.



It was sort of a fungus gnat Vesuvius, where a bunch of gnats looked like they were just in suspended animation. Interestingly, I find that when they first get stuck they stand upright, because as long as they're still alive they try to fly off. But once they die, the stick flat to the yellow trap. Again, sounds cruel but remember their brains aren't very big and they only live for about 10 days anyway.

A few days later, here's what it looked like.


I told you these pictures weren't for the faint of heart. The yellow traps were working to kill the adults as they hatched--and putting the yellow cards horizontally did a great job of catching dozens of them. But it seems that there were so many of them that at least some were getting through and continuing to lay eggs--and all it takes is one to lay 200 eggs.

All in all, I think Yellow Sticky traps are more useful for supporting other efforts to eradicate gnats, but they won't get rid of them all on their own (although for every one you trap, that's upwards of 200-300 eggs that won't be making it into your plants). For example, you can use them to monitor how well your other methods are working, and of course the more gnats on the yellow traps the less will be laying eggs. I brought myself a new batch of 25 Yellow Sticky Traps from Amazon (these are the same ones they sell at Gardener's Supply).

3) I did the old trick of dusting a layer of cinnamon on the top of the soil, something I had forgotten all about from my post in 2010. I took my big McCormick tub of cinnamon and just spread it to cover the soil on all the plants I knew to be infested, and separated the other plants from them. I don't know if it's the fine powder or the smell or both, but cinnamon is known to repel female gnats (rather than lay eggs on the cinnamon they'll fly around to try to find somewhere else). From what I could tell it's working in my case. And because cinnamon is a natural substance (it's just grated from bark of the Cinnamomum verum or a similar tree), you don't need to worry about chemicals harming you. Plus the lovely scent puts me in the mood for coffee cake every time I walk by the plant. A co-worker of mine dubbed my office "The Cinnamon Lair".

After a bit of research, it seems another advantage of cinnamon is that it kills the surface layer fungi (again, which grows on dead organic material). Now some say that having some fungi is actually a good thing for plants and you don't want to kill it all, and I've also read conflicting reports of how some people say the oils in cinnamon bark aren't great for plants if in excess, so it's best to just give it a dusting. But in my desperation I just poured a good 1/8th inch layer of cinnamon on the soil (it helps that years ago I didn't end up baking all the apple brown betties and apple pies and coffee cakes I thought I would when I bought that McCormick cinnamon years ago).

Sadly, while the cinnamon did seem to lessen the amount of gnats, it didn't wipe them away either. There were some larvae that were just deep enough in the roots that the kept coming.

4) Something else that helps at home is having a vacuum cleaner handy. As I said in 2010 I like to use my Dyson Hand-held because it's got powerful suck and it has a little clear plastic bin where I can see if I got the little guys. At work I don't have that luxury so I have to wait for them to fly by my face and then I do my Mr. Miagi on them (sans tiny chopsticks).

5) Sadly, after trying all of the above, I still had gnats flying around in both the office and at home. I'd think they were all gone and then one day one would fly up my nose. Exasperated, one day I scraped off the top inch or two from the corn plant soil and put that soil in the oven.


In desperation, I took a hair dryer in an attempt to dry out the top level of soil, used Saran Wrap to cover the top of the pot, and used duct tape to block the holes on the bottom.


As you can imagine, these didn't work either, again because the larvae were too deep in the root system to be killed by just wiping out the top, contrary to what a lot of blogs say.

6) Exasperated, I went to Amazon and searched for "nematodes". For those who don't remember from my earlier post what nematodes are, they're microscopic little parasitic worm-like animals that attack larvae of bugs like fungus gnats, but are completely safe for humans, animals, and even beneficial insects.

It's really fascinating to hear how they work--when you apply them to the soil (thousands of them at a time), they crawl through your soil looking for larvae, and once they find it they burrow into the larvae through its body openings and release a toxic bacteria into them. The larvae are killed in a day or two from blood poisoning, and then the nematodes reproduce inside the larvae. Once they reproduce, the exit the dead body and seek out new larvae to infect.

Okay, I know what you're thinking...words like "parasite" and "bacteria" and "toxic" and "infection" sound a bit scary. And it's true, there are some species that are harmful to animals and plants. But again, the ones you buy called "beneficial nematodes" (Steinernema feltiae) are perfectly safe for you, your pets, and your plants. So much so that the EPA doesn't even regulate them. In fact, they occur naturally in the soil but usually not at enough volume to kill larvae--so you're basically helping boost the number of them in your houseplant soil.

I ordered the one from "Dr. Pye". I thought of ordering the one I got last time from Gardener's Supply Company, but that mixed only one gallon and I needed a lot more.

I got the package yesterday. It came with a cold pack which was completely melted at at room temperature by the time I got it. Supposedly, though, nematodes have a shelf life of several weeks if refrigerated properly; mine had an expiration date stamped on it of September.


Here's the Scanmask product I got in the mail. It's basically a small zip-lock bag of what looks like fuzzy off-white powder. 


This company packages most of their nematodes for spraying outside, but I got the smallest package (1 million nematodes) for use indoors. They said to combine the contents of the bag with 1-5 gallons of water. I decided to cut the bag in half, and use half for my houseplants at home and half for the office. 


Once you fill your watering can with water, you dump the nematode "dust" in and wait 15 minutes. Then you agitate the can. This will make sure that the hundreds of thousands of little worms are spread evenly through the water.

You can't really see them with your naked eye, but if you pour them into clear glass dish or container and hold them to the light, you'll see the specks floating in the water. If you look real closely (it helps if you have a microscope or a magnifying glass), you'll see these specks wriggling. That's when you know your nematodes are alive. They may look creepy, and surely enough their cousins are known to be pretty nasty to plants, animals, and even humans, but these are the good guys. Unfortunately with this batch I couldn't really tell--it when I looked closely it looked like a few of mine were moving but most of them seemed awful still.

You do need to pre-water your plants to make sure the soil is moist, and then after that you water the plants with the nematode-filled water. Some people like to apply the nematodes directly to the soil, some like to dig a little hole in the soil to give them a head-start. Finally, you top it off with another watering to make sure they're in there good.

Ironically, at this point the important thing is to keep your soil moist the make sure the nematodes don't dry out but have a good environment to breed themselves, which sort of defeats #1 above.

After weeks of being tormented by gnats, I liked the idea of them munching away at the larvae. Unfortunately, after a while it was clear that these particular nematodes didn't work, probably because most of them had died during shipping. The corn plant (at home) and the fern and Dracena Warnekii (at work) were still so infested that the yellow sticky traps were still full of dead gnats each day, just a few at first but a few days later back to their usual amount. I ordered a new batch of nematodes from Gardener's Supply to see if that would help.

7) Finally, it was time to call out the big guns. I've read on various blogs how you can use hydrogen peroxide to kill gnats. You start out by getting a 3% solution (the kind you can find in the drugstore), and then diluting it with 4 parts water.

Then, you water your plants with the solution, covering the whole top layer of soil and letting the water run out of the bottom of the pot. The soil will start bubbling (sort of like it fizzes when you put it on an open wound)--what's happening is that because H2O2 is an unstable molecule, when it touches the soil it'll break down into an oxygen molecule (O) and a water molecule (H2O). Fungus gnat larvae will purportedly die on contact with the hydrogen peroxide, and as a bonus, the oxygen that's released will help kill fungus and mold that attracts it as well as prevent root rot by providing oxygen to the soil.

When I did this, I saw a flurry of gnats fly out. I was hoping that they didn't come back and their larvae have gone to that giant Golden Pothos in the sky.

Unfortunately, the next day I came to the office to find--you guessed it--a number of fungus gnats still buzzing around. I looked at the soil and saw plenty of creeping things in there. I've learned in my research that soil mites and springtails (both of which I saw in the soil) aren't bad things and one needn't obsess with getting rid of them. But I thought for sure the hydrogen peroxide bath would have at least cleared away some of them.

And so, I'm still fighting to get rid of these things. I'll try another batch of nematodes when I get them, but other than that I think just continuing to let the soil dry out is going to be the best approach.

The most important lesson I learned--DO NOT buy potting soil from the Kmart in Manhattan. Sadly, they are not doing a thing about cleaning up their store--look at what I saw just the other day in a section of Miracle Gro bags of potting soil (again, not for the faint of heart).


I feel sorry for anyone who buys soil from them because they're almost guaranteed to be bringing hundreds if not thousands of gnats and gnat larvae with them.

In fact, if you buy plants from them, keep them far, far away from all your other plants until their soil has completely dried out and you're sure there are no gnats nor gnat eggs.

And if you do buy potting soil anywhere, make sure the bag is sealed. If it has aeration holes, you might want to open the bag outside and let it dry out if you have any suspicion it might have gnat larvae (some have reported for brands like Miracle Gro that their sealed bags actually come with gnats in them).

I think over the years I've dealt with all the common houseplant pests--aphids, whiteflies, fungus gnats. The one common thing is to catch infestations before they start, by identifying where bugs are coming from (it's usually a plant) and cutting off the source, and then being persistent in fighting them before they take over your house or office, which can completely defeat the purpose of raising plants to help you have a clean, peaceful environment.




Wednesday, July 23, 2014

Red-Edged Dracaena (Dracaena Marginata) a.k.a. Dragon Tree: Best Air Cleaning Plant #20

Next on the list is the red-edged Dracaena, or dracaena marginata. Dr. Wolverton's book, he calls it the "Dragon Tree".

This is a lovely plant with narrow green leaves that have a deep green color and a red edge. Like other plants in the Dracaena family, it hails from Madagascar and other parts of tropical Africa. It's a hardy plant and supposedly one of the easiest to grow in the Dracaena family (although I find the Warneckii super-easy to grow too).

I purchased this one from Kmart, and like most plants I buy at Kmart, it was cheap and clearly in need of some TLC; there were fungus gnats in the soil, the tips of the leaves were drying out, and the color in the leaves were light and in some cases spotty. Still, like Charlie Brown and his tree, I figured, "Maybe all it needs is a little love".



I transplanted it into a larger pot, loosened the root ball, planted it in some good Miracle Gro potting soil, and gave it a good watering, but soon practically all the leaves had brown tips.


Dr. Wolverton gave some advice about the Warneckii that I believe I need to follow here with the Marginata: "trim dead tips with scissors, taking care to retain their natural shape".

I took his advice, and also his advice to make sure the soil was always moist but not soggy. Hopefully that should help the entire plant, from root to tips, take up the moisture properly. 

As for air cleaning, Dr. Wolverton rates this a 6/10 for chemical removal and a 7/10 for transpiration rate. He says it's among the best plants for removing xylene and formaldehyde. 

Some care tips:

  1. Temperature: Keep between 60-75 degrees Fahrenheit. 
  2. Sunlight: It likes partial shade. 
  3. Care and feeding: Keep soil moist. Feed regularly in spring and summer with liquid fertilizer or a good plant food like Osmocote Pellets
As a popular houseplant, you should have no problem finding one in a local garden store or Home Depot, or if you prefer there are plenty of Dracena Marginata plants for sale on eBay

Thursday, July 10, 2014

Dracaena Deremensis (Warneckii): Best Air Purifying Plant #17

This seems to be another houseplant with an identity crisis, and it's largely due to the fact that it's a cultivar--a cultivated variation of a plant that's been bred to bring out desirable qualities.

In the case of this plant, it's in the genus of dracaena. Dracena, which comes from the Greek word meaning "female dragon" is a genus with about 40 different species that are native to Africa and parts of southern Asian and Central America.

This particular plant is in the species d. fragrans, also knows as d. deremensis. It's been bred to contain an attractive pattern and given the name "Warneckii". They also call this particular variation "limelight" after the color of the leaves; while other variations are completely green or have white stripes, this one has a beautiful dark green color in the middle and light, lime-color on the outside, resembling the colors of a lime.

dracena warneckei (limelight)


This plant is closely related to other houseplants on the list such as the corn plant, which hopefully I'll be writing about soon.

The plant originated in Madagascar and thrives in other areas of tropical Africa such as Sudan, Mozambique, the Ivory Coast, and Angola. As with many tropical plants, it makes a great houseplant because it can survive brutal conditions and neglect.

It likes medium light, but can tolerate direct sunlight as well as low light conditions. As just one example, after I bought this particular plant I left it inside a plastic bag and unwatered for about a week, but lo and behold, the leaves didn't even start to wilt or turn brown.

As for air cleaning qualities, this whole genus of plant is a rock star, and is especially good at cleaning benzene from the air. According to the Center for Disease Control, air in general contains benzene from a large variety of sources, including tobacco smoke, gas stations, motor vehicle exhaust, and industrial emissions. Indoor air contains higher level of benzene than outdoor air, because in addition to all those sources you also add benzene found in glues, paints, furniture wax, and detergents.

Even low levels of benzene exposure can cause symptoms such as dizziness and headaches. With long-term exposure, it can cause harmful effects on bone marrow, decrease red blood cells, negatively affect the immune system, and lead to cancer or leukemia.

In Dr. Wolverton's ranking, this plant has a 6/10 effectiveness in clearing chemicals from the air and 8/10 transpiration rate, meaning that it can create relatively substantial air movement as water evaporates from its leaves.

Some care tips:

  1. Temperature: Keep between 60-80 degrees Fahrenheit, although it will tolerate colder temperatures for short periods
  2. Sunlight: It likes partial shade, but will tolerate both direct sunlight and low light levels
  3. Care and feeding: Keep the soil evenly moist. Feed during the summertime but not in the winter. Water less often during the winter. 
If you like the look of my lemon and lime colored Warneckii, you can shop your local garden store or find great ones on eBay.

Monday, June 23, 2014

Golden Pothos (Epipremnum aureum): Best Air Filtering Plant #24

I'd published this post earlier naming it as the #1 air cleaning houseplant, since this is the plant that's cited at the top of most lists and the famous TED Talk. The problem is, according to Dr. Wolverton's studies, this plant isn't at the top of the list for either filtering of chemicals nor for transpiration rate. I believe the reason it's at the top of so many lists is because it's so danged easy to grow, and a beautiful houseplant that's growing like a weed is ultimately going to be a better air cleaner than a fussy houseplant that doesn't want to grow at all. So I'll lead with this post again, but we'll give it its real ranking number from the revised list, which is #24. 

The first plant I bought at K-mart was a Golden Pothos. It was $6.99 but thanks to a rare confluence of events with their Shop Your Way rewards program, I managed to get it for a whopping eighteen cents.

The scientific name is Epipremnum aureum (or Scindapsus aureus or one of 23 other names, depending on who you ask). Now the botanists among you may be wondering why it's called "Pothos" but under the genus Epipremnum instead of the genus Pothos. And that's because it used to be classified under that genus, but is no longer. And now you know.

Some people call this the "Money Plant" and thus get it confused with the "Money Tree Plant" (Pachira aquatica). That's a great houseplant too, but not quite the same.

I put this first in the list because it's the one that comes up over and over again in the NASA report. It was one of the best all-around performers, removing 73% of benzene from a sealed experimental chamber in a 24-hour period (the fifth-best on the list) and 9.2% of Trichloroethylene (7th on the list). This plant was featured in a TED Talk by Kamal Meattle as one of the three essential plants for cleaning the air.

According to Dr. Wolverton, this plant originated in the Solomon Islands. It's native to Pacific regions like Australia, Malaysia, Indonesia, China, Japan, and India. It's actually a highly invasive species, meaning that given the right conditions in a tropical jungle, it'll grow and grow and grow. In fact, when the species has been introduced in places where it's not indigenous like Sri Lanka, it's been known to cause severe ecological disruption. This is probably why it's also been given names like "Devil's Ivy" and "Australian Native Monstera" (from the latin monstrum, probably referring to the unusual appearance of leaves).

Of course, the very hardiness that makes the plant so invasive in the tropics is what makes it one of the most beloved houseplants here at home. If you're like my wife and your picture is on plants' post office walls as the #1 most wanted killer of plants, you'll be surprised at how easy it is to grow the Golden Pothos.

The plant itself is lovely. It has heart-shaped leaves that are green and speckled with yellow (ergo, the "aureum" or "gold" in its name).



As for ideal growing conditions, think of the jungle--it grows best when it's not exposed to direct sunlight but in an area of your home or office that has access to bright but indirect light. Let the soil dry out between waterings.

golden pothos cleaning my office air


With very little care, your Golden Pothos will grow and grow and grow, limited only by the amount of sunlight you have and the size of your flower pot. And the more green you see, the more that plant will be pumping out clean oxygen for you and removing ickiness like benzene, formaldehyde, xylene, and toluene from the air.

One very important thing to note is that you should keep this plant out of the reach of cats, dogs, and children because of the presence of raphides (calcium oxalate) which can cause some nasty toxic reactions if swallowed. Raphides are actually tiny, microscopic needle-shaped crystals that botanists believe is a defense mechanism, like pricks on a cactus. To be safe, when pruning the leaves use gloves (the plant liquids can cause irritation), and absolutely do NOT ingest leaves or let animals or children do so.

If you're looking for a golden pothos, you can most likely find one at a local shop like K-mart, Walmart, Home Depot, or a garden store. If you're rather get one online, you can try this product on Amazon or look for one on eBay.

Some care tips:

1) Temperature: Keep between 65-75 degrees Fahrenheit. Never let it drop below 50 degrees.
2) Sunlight: It likes partial shade or shade.
3) Care and feeding: Let the soil dry completely between waterings. Feed weekly from March to August.

Monday, June 16, 2014

The Best Air Purifying Houseplants - For Real This Time

In my last post I shared with you my new obsession--finding the best air cleaning houseplants and putting them in my office.

The problem is that there are dozens and dozens of Web sites out there that claim to have the list of "the best" plants for purifying air, and it seems that none of these lists match. Worse, most of these lists (mine included) draw extensively from the 1989 NASA study. The problem is that most people who cite this list (myself included) just take the list of plants from the study without reading the study. Had they read the study, they'd realize that the house plants chosen for this study were chosen more or less at random, so while all of them were found to have some level of air filtering properties, this list hardly represents "the best".

As I mentioned, the scientist who headed up this study, Dr. B.C. Wolverton, wrote a book on the subject called How to Grow Fresh Air: 50 House Plants that Purify Your Home or Office. I went and bought me a copy on Amazon.


air filtering houseplants book


The book is absolutely fantastic, and gives as definitive an answer as I've seen anywhere on what the top air filtering houseplants truly are.

Something I loved about this book was that Dr. Wolverton goes into the science of how houseplants clean air in a way that's really understandable (unlike trying to read his NASA study, which admittedly wasn't intended for a consumer audience). For example, he does talk, in layman's terms, about the original study, but also provides some intriguing facts, such as:
  • By far the most common toxin in the air is formaldehyde, particularly in office settings. Formaldehyde is found in resins; tobacco smoke; gas stoves; and consumer products from garbage bags to paper towels to fabrics to permanent press clothes to carpet backing and floor adhesives. It's also used materials such as particle board and plywood that make up office walls and furniture. Many have cited the increased us of formaldehyde as correlating to increased numbers of people with asthma, cancer, respiratory disease, and more. And we're not even talking about other pollutants like xylene, toulene, benzene, trichloroethylene, chloroform, ammonia, and acetone. The good news is, we don't need more chemicals to fight this, as the good Lord has already invented the perfect air filtration system.
  • Some people believe that when plants absorb toxins from the air, when that plant dies the toxins will all return to the air. This is not the case--their studies showed that plants actually take airborne toxins and deliver them to microbes living around their roots, which then break down the toxin, literally "removing" them, not storing them in any way.
  • Plants placed in a "personal breathing zone" (a 6-8 cubic foot of space near, say, your office desk, computer, or sofa where you watch TV) can add humidity, remove bioeffluents (pollutants humans expel from their bodies) and chemical toxins in the air, and suppress airborne microbes, resulting in better health!
  • Plants also release phytochemicals that suppress mold spores and bacteria found in the ambient air. Research shows that rooms filled with plants can have 50-60% less airborne mold and bacteria than rooms without plants.
  • Plants really do "breathe". The technical word for it is "transpiration", where water evaporates from plant leaves to create "movement of air". Transpiration rate is a vital factor in removing toxins. Many of the most effective houseplants in the list have unusually high rates of photosynthesis and unusually high transpiration rates. It's the perfect air filtration system, as carbon dioxide is removed from the air and the soil, pure oxygen is released into the air, and toxins are drawn into the leaf and moved to the root zone for microbes to break it down. 
In the rest of the book, Dr. Wolverton rates 50 houseplants using a rating system he devised that combines four elements: 1) its ability to remove chemical vapors, 2) its ease of growth and maintenance, 3) its resistance to insect infestation, and 4) its transpiration rate. If you'd like to see his full list ordered by this rating system, I definitely encourage you to buy the book, which also provides excellent scientific information about air cleaning plants and descriptions and great photos of each of the 50 plants.

plants that clean chemicals from the air


Since I consider myself a pretty seasoned amateur horticulturalist (or so I like to think), #2 is less of a concern for me. And since I'll be growing my houseplants in an office environment where it's difficult for insects to get into unless they have a building pass, #3 isn't too much of a concern either.

So I've taken the liberty of re-ordering Dr. Wolverton's list to focus on the plants he rated most highly for #1, its ability to remove chemicals from the air and #4, the ability of the plant to more or less circulate air on their own.

Here's the re-ordered list:
  1. Boston Fern (Nephrolepis exaltata "Bostoniensis") - Chemical removal=9/10, Transpiration=9/10
  2. Areca Palm (Chrysalidocarpus lutescens) - Chemical removal=8/10, Transpiration=10/10
  3. Bamboo Palm (Chamaedorea seifrizii) - Chemical removal=9/10, Transpiration=9/10
  4. Kimberly Queen (Nephrolepis obliterata) - Chemical removal=9/10, Transpiration=9/10
  5. Gerbera Daisy (Gerbera jamesonii) - Chemical removal=9/10, Transpiration=8/10
  6. Florist's Mum (Chrysanthemum morifolium) - Chemical removal=9/10, Transpiration=8/10
  7. Peace Lily (Spathiphyllum sp.) - Chemical removal=8/10, Transpiration=8/10
  8. English Ivy (Hedera helix) - Chemical removal=9/10, Transpiration=7/10
  9. Rubber Plant (Ficus robusta) - Chemical removal=9/10, Transpiration=7/10
  10. Dwarf Date Palm (Phoenix roebelenii) - Chemical removal=9/10, Transpiration=7/10
  11. Schefflera (Brassaia actinophylla) - Chemical removal=8/10, Transpiration=7/10
  12. Corn Plant (Dracaena fragrans "Massangeana") - Chemical removal=8/10, Transpiration=7/10
  13. Dracena "Janet Craig" (dracena deremensis "Janet Craig") - Chemical removal 8/10, Transpiration=7/10
  14. Lady Palm (Rhapis excelsa) - Chemical removal=7/10, Transpiration=8/10
  15. Ficus Alii (Ficus macleilandii "Alii") - Chemical removal=7/10, Transpiration=8/10
  16. Weeping Fig (Ficus benjamina) - Chemical removal=8/10, Transpiration=6/10
  17. Dracaena "Warneckei" (Dracaena deremensis "Warnecki") - Chemical removal=6/10, Transpiration=8/10
  18. Dumb Cane (Dieffenbachia "Exotica Compacta") - Chemical removal=7/10, Transpiration=7/10
  19. King of Hearts (Homalomena wallisii) - Chemical removal=7/10, Transpiration=7/10
  20. Dragon Tree (Dracaena marginata) - Chemical removal=6/10, Transpiration=7/10
  21. Dwarf Banana (Musa cavendishii) - Chemical removal=5/10, Transpiration=8/10
  22. Dendrobium Orchid (Dendrobium sp.) - Chemical removal=7/10, Transpiration=5/10
  23. Lily Turf (Liriope spicata) - Chemical removal=7/10, Transpiration=5/10
  24. Golden Pothos (Epipremnum aureum) - Chemical removal=5/10, Transpiration=7/10
  25. Dumb Cane (Dieffenbachia camilla) - Chemical removal=5/10, Transpiration=7/10
  26. Spider Plant (Chlorophytum comosum "Vittatum") - Chemical removal=6/10, Transpiration=5/10
  27. Dwarf Azalea (Rhododendrom simsii "Compacta") - Chemical removal=6/10, Transpiration=5/10
  28. Red Emerald Philodendron (Philodendron erubescens) - Chemical removal=6/10, Transpiration=5/10
  29. Peacock Plant (Calathea makoyana) - Chemical removal=5/10, Transpiration=6/10
  30. Tulip (Tulipa gesneriana) - Chemical removal=7/10, Transpiration=3/10
And so, I thought I'd try to "reboot" this series of posts I'm going to make about plants that clean the air by focusing on Dr. Wolverton's latest list. As before, my goal is ultimately to get as many of these plants filling my office as possible and really getting the air clean and pure.

Using Dr. Wolverton's book and all those other Web sites out there reference, I'll share my own personal experiences about growing these plants and talk about which ones from my experience are easy and which aren't.