What a Peace Lily Actually Does
A peace lily is a houseplant with dark green leaves and white flowers that grows well indoors with low light. It's popular partly because it looks attractive on a shelf or desk, but also because research suggests it removes certain chemicals from the air around it—specifically formaldehyde, benzene, and ammonia, which can come from furniture, cleaning products, and building materials. The plant absorbs these through its leaves and roots, then breaks them down.
That said, a single peace lily won't clean an entire room. Studies show the effect is real but modest: you'd need several plants, or a very small space, for the air-cleaning to make a noticeable difference to indoor air quality on its own. The bigger benefit for most people is straightforward having a living plant in your space, which research connects to lower stress and better focus.
Key Takeaways
- Peace lilies remove small amounts of formaldehyde, benzene, and ammonia from indoor air, though one plant covers only a limited area.
- The plant thrives in low light and needs water only when the soil feels dry, making it one of the easiest houseplants to maintain.
- Having any living plant nearby is linked to reduced stress, better concentration, and improved mood in studies of indoor environments.
- Peace lilies are toxic to pets and young children if eaten, so placement matters if you have animals or small kids at home.
- The plant signals when it needs water by drooping noticeably, so you don't need to guess or follow a strict watering schedule.
How Peace Lilies Clean Air
The air-cleaning happens through a process called phytoremediation. The plant's leaves have tiny pores that absorb airborne chemicals, and the roots—along with soil microbes—break those chemicals down into harmless compounds. NASA researchers studying this effect in the 1980s found that peace lilies were among the most effective houseplants at removing formaldehyde and other volatile organic compounds, or VOCs.
However, the scale matters. A peace lily in a bedroom removes VOCs from the air when ready around it, but the effect weakens with distance and doesn't replace ventilation or air filters in larger spaces. If you live in a home with new furniture, fresh paint, or frequent chemical use, a peace lily is a useful addition—not a substitute for opening windows or using an air purifier.
Why People Keep Them for Stress and Focus
Beyond air cleaning, research on indoor plants shows that having greenery nearby lowers cortisol (a stress hormone) and blood pressure, and improves attention span. A study published in the Journal of Environmental Psychology found that people working in rooms with plants reported feeling calmer and more productive than those in plant-free spaces. The effect appears to come from both the visual presence of living things and the act of caring for them.
Peace lilies are particularly good for this because they're low-maintenance. You don't need to remember a watering schedule or worry about special lighting. The plant tells you when it's thirsty by drooping visibly, which gives you a straightforward, regular task—something researchers call "micro-care" that can reduce anxiety without feeling like a chore.
Care Requirements and Where to Place One
Peace lilies grow in low to medium indirect light, which makes them ideal for offices, bedrooms, or living rooms away from direct sun. They prefer soil that's moist but not waterlogged; water when the top inch of soil feels dry to the touch, usually once a week depending on your home's humidity. In winter, they need less water. The plant will droop dramatically when thirsty, but it bounces back within hours of watering—a visual feedback that helps you learn its rhythm.
Temperature matters less than consistency. Peace lilies do best between 65 and 75 degrees Fahrenheit, which covers most indoor home temperatures. They appreciate humidity, so misting the leaves or placing the pot on a pebble tray with water underneath can help, especially in dry climates or heated homes. Fertilize once a month during growing season (spring and summer) with a balanced houseplant fertilizer diluted to half strength.
Safety Considerations for Pets and Children
Peace lilies contain calcium oxalate crystals, which are toxic if eaten. For cats and dogs, ingestion causes mouth irritation, drooling, and difficulty swallowing; for young children, it can cause similar oral irritation and stomach upset. The plant is not lethal in small amounts, but it's worth keeping out of reach of pets that chew plants and toddlers who put things in their mouths.
If you have pets or young children, place the peace lily on a high shelf, in a hanging planter, or in a room they don't access unsupervised. If accidental ingestion happens, contact poison control or your veterinarian—they'll want to know the amount and can advise whether observation or treatment is needed.
Peace Lilies Compared to Other Air-Cleaning Plants
Other houseplants also remove VOCs: spider plants, snake plants, and pothos are commonly cited. Spider plants are equally straightforward to grow and non-toxic to pets, making them a better choice if you have animals. Snake plants tolerate even lower light and need less water, but they grow more slowly. Pothos is hardy and fast-growing but is also toxic to pets.
Peace lilies stand out because they combine moderate air-cleaning ability, low-light tolerance, straightforward care, and visible feedback (the drooping signal). They're also the only common houseplant that flowers indoors reliably, which some people find more rewarding than foliage-only plants. The choice between them often comes down to your space, your pets, and whether you want a plant that flowers.
What the Research Actually Shows
The evidence for air cleaning is real but limited in scope. Studies confirm that peace lilies remove formaldehyde, benzene, and ammonia in controlled laboratory settings. However, real homes are more complex: air circulation, room size, outdoor air exchange, and the number of plants all affect how much cleaning actually happens. One peace lily in a large, well-ventilated home will have a smaller effect than the same plant in a small, sealed room.
The stress and focus benefits are stronger and more consistent across studies. Multiple peer-reviewed papers show that the presence of plants indoors correlates with lower anxiety, better mood, and improved concentration. This effect doesn't require the plant to be actively cleaning air—it appears to come from the visual and psychological presence of living things, which humans respond to even unconsciously.
Frequently Asked Questions
Do I need multiple peace lilies for air cleaning to work?
One plant removes some VOCs from the air around it, but the effect is modest. If air quality is a primary concern, multiple plants plus ventilation and air filters work better together than any single approach. For stress and focus benefits, even one plant makes a difference.
Can a peace lily survive in a dark corner with no windows?
Peace lilies tolerate low light better than most plants, but they still need some indirect light to grow. A dark corner with no natural light will cause the plant to weaken over time. A spot near a window with a sheer curtain, or under artificial grow lights, works well.
Why is my peace lily drooping even after I water it?
Drooping after watering usually means overwatering or poor drainage. Peace lilies prefer soil that dries out slightly between waterings. Check that the pot has drainage holes and that you're not watering more than once a week. If the soil stays soggy, root rot may be developing—repot into fresh, drier soil.
Is a peace lily safe if I have a cat?
Peace lilies are toxic to cats if eaten. If you have a cat that chews plants, choose a non-toxic alternative like a spider plant, or place the peace lily where your cat cannot reach it—a high shelf or hanging planter works well.
How long does it take a peace lily to clean the air in a room?
The plant begins removing VOCs as soon as it's in the space, but the effect is gradual and depends on air circulation. In a sealed room, it may take days to weeks to noticeably reduce chemical levels. In a room with windows and air movement, the effect is smaller because fresh air exchange happens faster than the plant can clean.