The peace lily or spathiphylllum (Spathiphyllum spp.), also called spathe leaf or white sails, is one of the most popular houseplants and with good reason. Very few houseplants that bloom so beautifully are as easy to grow. And it’s not just a flowering plant. Thanks to its attractive leaves, it makes a stunning foliage plant as well. It is often offered too as an excellent plant for air purification, although that point is debatable. (Hint, pretty much any healthy plant will clean the air.)
Its botanical name means “leaf spathe”, referring to the white leaflike bract (spathe) that protects the true flowers. The latter are found on a columnar white to yellow structure called a spadix in front of the spathe. They’re very tiny—just little white bumps on the spadix—and scarcely noticeable, although you’ll find them shedding a bit of white pollen occasionally. Often too the flower is faintly scented at night. The inflorescence can last for well over a month, slowly turning greenish. I’ve never seen one produce seeds in a home setting.
The plant forms a rosette of attractively veined, dark green pointed leaves arching outwards, usually quickly surrounded by offsets, and is stemless at first. However, over time, as new leaves appear from the top of the rosette and lower ones are removed, a short stem will appear.
A Bit of Background
The peace lily hails from Central and South America where it usually grows in tropical rainforests, although I’ve seen it positively thriving in full tropical sun in Costa Rica, albeit in very soggy soil. It’s an aroid, that is, a member of the Araceae or philodendron family, a group that includes other popular, low-light foliage plants like pothos, monsteras and syngoniums and also a few flowering plants, like anthuriums.
The common name peace lily derives from the resemblance of the inflorescence to that of the calla lily (Zantedeschia spp.), another aroid. Neither resemble a true lily (Lilium) in any way. Where the name “peace” comes from, though, I have no idea.
There are about 40 species of spathiphyllum, a few possibly still grown as houseplants (S. wallisii, for example), but most spathiphyllums you’ll see today are hybrids. They can range in size from no bigger than a coffee cup to as tall as a human being (notably the giant cultivar ‘Sensation’). Some, ‘Domino’ for example, have variegated leaves.
Growing Spathiphyllums Well
Although spathiphyllums are touted as easy-to-grow houseplants, they aren’t really the toughest plants around. They notably truly dislike drying out and will wilt like lettuce in the sun if you don’t water them regularly. Do that too often—or leave one without water for too long a time—and your plant will be toast! That’s why the main rule in spathiphyllum care is to remember to water them, always. As soon as the soil feels even slightly dry to the touch, pour on enough water to thoroughly moisten the root ball.
Some authorities recommend using the earliest signs of wilting to recognize when the plant needs watering. They’ve got it wrong! Wilting even slightly damages the plant, causing root damage and eventually leading to brown leaf tips. Here’s the real truth: moist soil = happy spathiphyllum. It’s that simple!
How often do you need to water them? That will depend on your growing conditions, the size of the pot and how full of offsets the pot is, but it can be more than once a week under some circumstances. Under low light, though, where the plants struggle a bit more to survive, you have to be careful to water more moderately and certainly not let the pots soak in water for long periods.
The main selling point for spathiphyllums is that they tolerate low light … and they do. But what the salesperson doesn’t tell you is that they won’t bloom in low light, not indoors at least. Maybe in some tropical forest, they would. If you want flowers, they’re going to need at least moderate light and—yes!—possibly some direct sun. Ideally, you’d set them in a well-lit room, but back from the window. They do very well in office settings where most of the light comes from overhead fluorescent lamps … but will bloom better if you set them on top of filing cabinets, nearer the source of light, then on the floor.
Spathiphyllums will let you know if they’re getting too much light (a surprisingly rare phenomenon), as the leaves will start to turn yellow and curl under. Full outdoor sun may even cause leaves to burn, leaving black necrotic marks, so if you put your spathiphyllums outdoors for the summer, keep them in at least moderate shade.
Spathiphyllums grown in bright light will flower abundantly, mostly heavily in the spring, but sporadically throughout summer and fall and sometimes even in winter. Those grown in low light will struggle to bloom at all.
All the rest is routine houseplant care. They like warm temperatures indoors, above 55˚ F (13˚ C) at all times (they’ll tolerate less down to 45˚ F/7˚ C, but why stress them?). They also like good atmospheric humidity, but will put up with dry air. Don’t spray the leaves in trying to remedy this: you can spread diseases (more about that below). Instead use a humidifier or a humidity tray to keep humidity up. They don’t require much fertilizer. I suggest using fertilizer as a reward, applying any all-purpose fertilizer at ¼ the recommended rate whenever they come into bloom.
Cut off or remove faded flowers and yellowing leaves as needed. Dead leaves often cling stubbornly to the stem, as they wrap right around it at the base. Read When Dead Leaves Just Won’t Let Go! to learn how to remove them more easily.
Most spathiphyllums produce offsets (baby plants) at their base and, indeed, the pot often fills with them, creating serious competition for resources, often to the point where the mother plant actually starts to shrink in size and bloom less. So you have to pot spathiphyllums into larger and larger pots over time … and eventually, divide them. When you split them up, I suggest starting off with just one to three plants per pot. You may find this results in dozens of babies to give away!
You can repot them at any time during the growing season, but it’s best not to repot in winter, when they’re a bit stressed out and will take longer to recuperate.
Repot into a container large enough to readily hold the root ball, using just about any potting soil. Set the plant lower in its pot than it was originally so that any bare stem—already covered in short, stubby adventitious roots—is covered. These roots will soon lengthen and come to strengthen the plant. Finish by watering well.
Pests and Diseases
Spathiphyllums aren’t particularly subject to pests, but mealybugs, scale insects and aphids will attack almost any plant, spathiphyllums included. Repeated treatments with insecticidal soap or neem may be needed to control them. The best way of avoiding such problems is to carefully inspect plants before you buy them and keep any houseplants that are so infested away from your spathiphyllums.
Root rot is possible, especially if you overwater a plant that previously had suffered root loss to underwatering. If your plant wilts even when you water well, and if the soil smells like a rotten potato, it probably has root rot. I’d suggest culling such a plant, tossing its soil, and thoroughly cleaning its pot before reusing it. You could, however, always try to save a healthy offset or two … if there are any!
Leaf spots, patches of yellow or dead tissue caused by fungus or bacteria, are possible and are best prevented by not buying infected plants. Since most spathiphyllums these days are grown from tissue culture, that is, in laboratories under sterile conditions, they’re usually disease-free when you get they get to the store. However, if your local supplier doesn’t keep fairly sterile conditions (yes, I do mean those big box stores whose plants always seem half dead!), they can pick them up there. Also, diseases can spread from your other houseplants, notably if you have the bad habit of regularly spraying your plants with water. I recommend only spraying spathiphyllum leaves when you’re cleaning them, something you only really need to do once a year at the most.
Brown leaf tips or edges? This is usually caused by chronic underwatering. Water is simply not making its way all the way to the tip of the leaves. The other cause is soil contaminated with excess mineral salts. You can try leaching to remove some of the contaminants, but repotting into fresh soil is a much better way of solving the problem.
There are dozens of spathiphyllum cultivars — ‘Chopin’, ‘Clevelandii’, ‘Mauna Loa’, ‘Petite’, ‘Sensation’, ‘Sweet Pablo’, etc. —, but the plants you see in garden centers are usually sold without any label. (Typically, nursery owners believe home gardeners don’t care about such things. They’re wrong!) Given the impossibility of getting a correct identification, I suggest just buying a spathiphyllum whose size and appearance suits you. If you want to start collecting known varieties, you’ll be pretty much forced to contact specialized nurseries.
Yes, spathiphyllums are considered poisonous to both humans and pets. Like all aroids, they contain oxalic acid, which can cause a needlelike burning sensation in the mouth and even greater irritation if swallowed. In fact, though, just how toxic they are has never been studied and there appear to be no cases of serious poisoning on record. Simply biting into a leaf causes enough instant discomfort, without doing any serious harm, that the person or animal usually stops immediately.
Peace lilies: easy enough to grow, but if you want flowers, give them more light!