Spider Plant Care: The Air Purifier

Spider Plant Care: The Air Purifier

I bought my first spider plant three years ago because someone on the internet said it was “impossible to kill.” That person lied. Well, sort of. I did kill my first one by overwatering it into oblivion, but the second one has been thriving on my bookshelf ever since. Now I have four of them scattered around my apartment because they keep making babies, and honestly, I can’t bring myself to throw away a perfectly good plantlet.

Spider plants got really popular in the 1970s when NASA published research showing they could remove formaldehyde from the air. A lot of people still buy them for that reason, though the actual air purifying effect in a normal home is pretty minimal unless you have about 10 plants per square foot. I keep mine because they’re forgiving, they look nice in hanging baskets, and my cat hasn’t figured out how to reach the one in the bathroom yet.

If you’re reading this because your spider plant looks sad, or because you just brought one home and want to avoid my early mistakes, I’ve spent way too much time figuring out what these plants actually need. Not what the care tag says, but what works in a real apartment with inconsistent watering schedules and questionable light.

Best spot for a Spider Plant

Spider plants are from South Africa, where they grow in partial shade under trees and in forest edges. That tells you something useful right away. They don’t want full sun blasting them all day, but they also don’t want to sit in a dark corner.

I keep one on a shelf about six feet from my east-facing window. It gets bright light in the morning but nothing direct after about 10 AM. This plant has the most babies and the deepest green color. The one I tried keeping in my bedroom, which only has a north-facing window, grew really slowly and the leaves got pale and floppy. It wasn’t dying, but it looked depressed.

According to the Clemson Cooperative Extension, spider plants do best in bright indirect light but can tolerate lower light conditions. The catch is that lower light means slower growth and less variegation if you have one of the striped varieties. My variegated spider plant lost some of its white stripes when I moved it to a dimmer spot. When I moved it back near the window, new growth came in with stronger stripes again.

Direct sun is where people mess up. I tried putting one on my south-facing windowsill last summer because I thought more light would equal more growth. The leaves got sunburned. They turned pale brown and crispy at the edges, and the whole plant looked bleached out. Spider plants can handle some morning sun or a bit of evening sun, but midday sun through a window will scorch them.

If your apartment is on the darker side like mine used to be, spider plants will survive under fluorescent lights or even in a bathroom with just a small window. They won’t grow fast, and they probably won’t make babies, but they’ll stay alive. I kept one in my old bathroom for over a year, and it looked fine. Just green and calm, doing its thing.

Temperature-wise, spider plants are pretty flexible. They like normal room temperatures between 60 and 75 degrees Fahrenheit. Mine have been fine down to about 55 degrees in winter near the window. The University of Minnesota Extension notes that they don’t like cold drafts or sitting right next to heating vents, which makes sense. Nobody likes that.

Watering: When the leaves look pale

This is where I killed my first spider plant. I thought “easy care” meant I should water it every few days like a needy fiddle leaf fig. Wrong. Spider plants have thick, tuberous roots that store water. They’re built to handle some drought.

I water mine when the top two inches of soil feel dry. I stick my finger in the pot, and if it feels dry past my first knuckle, I water. This usually ends up being about once a week in summer and every 10 to 14 days in winter. Your schedule will be different depending on your light, humidity, and pot size.

The biggest clue that your spider plant needs water is when the leaves start to look pale or less firm than usual. Not wilted exactly, but less perky. The tips might start to fold slightly lengthwise. When I see that, I water thoroughly until water runs out the drainage holes. Then I don’t water again until the soil dries out.

Overwatering is worse than underwatering. If you water too often and the soil stays wet, the roots rot. This happened to my first plant. The center leaves turned yellow and mushy, and when I pulled the plant out, the roots were brown and smelled bad. According to the University of Georgia Extension, root rot from overwatering is one of the most common ways people kill spider plants.

One thing I learned from the North Carolina State University Extension is that spider plants are sensitive to fluoride and chlorine in tap water. If your water is heavily treated, you might notice the leaf tips turning brown even when everything else is fine. I started filling a pitcher with tap water and letting it sit overnight before watering. This lets the chlorine evaporate. It’s helped a bit with the brown tips, though I still get some.

If you have access to rainwater or distilled water, that’s even better. I don’t usually bother with distilled water because it feels excessive for a spider plant, but when I’ve used rainwater, I swear the plant looks happier.

Above: A close up look at the symptoms.

Why the tips always turn brown

Almost every spider plant I’ve ever seen has brown tips. Mine do. My friend’s do. The ones at the plant store do. It’s so common that I’ve started thinking of it as just part of having a spider plant. But there are reasons for it, and you can minimize the browning even if you can’t eliminate it completely.

Fluoride and chlorine in tap water are the main culprits. Most municipal water contains fluoride, and spider plants accumulate it in their leaf tips over time. The tips turn brown and crispy. The University of Florida IFAS Extension explains that fluoride toxicity is a known issue with spider plants and a few other houseplants like dracaenas.

Like I mentioned before, letting tap water sit out overnight helps. You can also use filtered water or rainwater if you’re really bothered by the brown tips. I’ve tried all three methods, and honestly, the brown tips still happen, just less aggressively.

Low humidity is another factor. Spider plants prefer humidity around 40 to 50 percent, which is higher than most heated apartments in winter. I don’t run a humidifier specifically for my plants because that feels like too much effort, but I do keep one spider plant in the bathroom where the humidity is naturally higher from showers. That one has fewer brown tips than the others.

Overfertilizing can also cause tip burn. I made this mistake when I first got into plants and thought more fertilizer would make everything grow faster. The tips turned brown and crispy almost overnight. Now I fertilize my spider plants maybe once a month during the growing season with a diluted liquid fertilizer at half strength. In winter, I don’t fertilize at all.

You can trim brown tips with scissors if they bother you. I cut just the brown part off at an angle so it looks more natural. Some people say this stresses the plant, but I haven’t noticed any problems. The University of Vermont Extension mentions that trimming cosmetic damage is fine and won’t harm the plant.

The other thing to know is that brown tips can just be older leaves aging out. If the whole leaf is yellowing and browning from the tip down, and it’s one of the outer older leaves, that’s normal. I pull those off completely at the base when they look too ratty.

Soil mix for fast growth

Spider plants aren’t picky about soil, but they do grow faster and look healthier in a well-draining mix. I use a standard potting mix and add about 30 percent perlite to it. This keeps the soil from staying too wet and gives the roots air space.

The thick tuberous roots need oxygen. If the soil is too dense and stays compacted, the roots suffocate and growth slows down. I learned this from the University of Minnesota Extension, which recommends a loose, well-draining potting mix for spider plants.

You can also use a cactus and succulent mix if you have some lying around. I’ve tried this, and it works fine. Spider plants aren’t succulents, but they tolerate the faster draining soil well. Just be aware that you might need to water a bit more frequently because the soil dries out faster.

I repot my spider plants every two years or so, usually in spring. When the roots start coming out of the drainage holes or circling tightly around the inside of the pot, it’s time. I go up one pot size, refresh the soil, and trim any roots that look dead or mushy.

One weird thing about spider plants is that they seem to produce more babies when they’re slightly root-bound. I had one plant that exploded with plantlets right before I repotted it, almost like it was panicking and trying to reproduce before it ran out of space. The Missouri Botanical Garden mentions that spider plants flower and produce offsets more readily when they’re pot-bound, so there might be something to that.

For fertilizer, I use a balanced liquid houseplant fertilizer diluted to half the recommended strength. I apply it about once a month from spring through early fall. In winter, I stop fertilizing because the plant isn’t actively growing. Over-fertilizing leads to salt buildup in the soil, which contributes to those brown tips I talked about earlier.

Above: The tools you need to fix this.

Is it safe for cats to eat?

This is probably the question I get asked most often about spider plants. Yes, they’re non-toxic to cats and dogs according to the ASPCA. My cat, Luna, has nibbled on the leaves a few times, and she’s been completely fine. No vomiting, no diarrhea, no weird behavior.

That said, spider plants have a reputation for attracting cats. Some people think the plants contain compounds similar to catnip, but I haven’t found solid research backing that up. What I do know is that cats seem weirdly drawn to spider plants. Luna ignores my pothos and my snake plant, but she will go out of her way to chew on a spider plant leaf if I leave one within reach.

The dangling plantlets are especially tempting. They swing when the cat bats at them, which triggers the hunting instinct. I had to move my hanging spider plant higher after Luna figured out she could leap from the couch and grab a plantlet mid-air. It was impressive but also annoying.

Eating spider plant leaves won’t poison your cat, but eating a lot of plant matter can cause mild stomach upset. Luna threw up once after eating too much spider plant, but it was just undigested plant bits and she was fine an hour later. The University of California Division of Agriculture and Natural Resources notes that while spider plants are non-toxic, eating large amounts of any plant material can cause vomiting in cats just from the physical irritation.

If you want to keep your cat away from your spider plants, the easiest solution is to put them somewhere the cat can’t reach. High shelves work. Hanging baskets work if your cat isn’t a jumper. I also keep a pot of cat grass on the floor as an alternative, which Luna mostly ignores in favor of trying to destroy the spider plant.

Some people spray their plants with diluted lemon juice or bitter apple spray to deter cats. I tried this once, and it worked for about two days before Luna decided she didn’t care. Your cat might be different.

The good news is that even if your cat does munch on your spider plant occasionally, you don’t need to panic. It’s annoying for you and possibly bad for the plant’s appearance, but it’s not dangerous for the cat.

I’ve stopped stressing about it. Luna gets her occasional spider plant snack, the plant keeps growing, and I trim the chewed leaves when they look too bad. It’s not the hill I’m choosing to die on in the ongoing battle of keeping plants and cats in the same apartment.

References

ASPCA. “Spider Plant.” Animal Poison Control. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/spider-plant

Clemson Cooperative Extension. “Spider Plant.” Home & Garden Information Center. https://hgic.clemson.edu/factsheet/spider-plant/

Missouri Botanical Garden. “Chlorophytum comosum.” Plant Finder. https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=279699

North Carolina State University Extension. “Chlorophytum comosum.” NC State Extension Gardener Plant Toolbox. https://plants.ces.ncsu.edu/plants/chlorophytum-comosum/

University of California Division of Agriculture and Natural Resources. “Safe and Poisonous Garden Plants.” UC IPM Online. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/poisonous.html

University of Florida IFAS Extension. “Fluoride Toxicity.” Environmental Horticulture. https://edis.ifas.ufl.edu/publication/EP111

University of Georgia Extension. “Growing Indoor Plants with Success.” Circular 672. https://extension.uga.edu/publications/detail.html?number=C672

University of Minnesota Extension. “Spider Plant (Chlorophytum comosum).” Yard and Garden. https://extension.umn.edu/find-plants/houseplants/spider-plant

University of Vermont Extension. “Houseplant Care.” Department of Plant and Soil Science. https://www.uvm.edu/extension/horticulture/houseplants