Mistakes Everyone Makes When Watering Peace Lilies (And How To Do It Right)

Some people find peace lilies (Spathiphyllum spp.) among the easiest houseplants they care for and even classify them as one of those plants that seem to thrive on neglect. But others find them among the most difficult to care for properly. Members of the Spathiphyllum genus are certainly particular, and perhaps that makes things difficult for people with different plant care habits. But the watering preferences of the peace lily aren't really that different from those of many other plants. Perhaps the difficulties have to do with being unaccustomed to taking care of indoor plants, or maybe people just feel more stress over peace lilies because they're often acquired in ways with emotional associations, like funerals or illnesses.

Whatever the case, the basics of watering – that is, when and how to water them – aren't difficult to master. Using the "let it droop" method of allowing a plant to wilt before watering is a common mistake that stresses the peace lily unnecessarily, and can lead to discolored and unhealthy leaves. But because water needs are affected by a lot of factors like the season, light conditions, the temperature of the immediate environment, pot size, and other things, it's best to water peace lilies when the soil reaches the right level of dryness. Allow the top 2 inches of soil to become dry, then water the peace lilies until water runs out of the drainage holes. Just be sure to catch the need before they start to droop ... usually 10 to 12 days after the last watering.

If you're used to growing hearty annuals and vegetables that don't seem to care much about the quality of their water, it might surprise you to learn how finicky a peace lily can be about its drinking habits. It seems to be more sensitive to chlorine than most houseplants, and some gardeners believe they're also sensitive to fluoride. So, you may want to hydrate your peace lilies with water that's been filtered or purified to some extent to avoid the negative effects tap water has on some plants. 

You can get carried away, though; whatever the effects of distilled water on plants, distilled bottled water is unnecessary and it's probably sufficient to let water from your taps sit for a day or so to allow volatile chemicals like chlorine to evaporate. You can also use filtered water, so long as the filtration removes chlorine, and both reverse-osmosis water and untreated well water will work as well. Growers differ on the subject of rainwater, but most say it is fine for Spathiphyllum species. Do avoid straight tap water, though, and don't make a habit of watering anything with bottled water.

Because peace lilies are sensitive to cold and to rapid temperature fluctuations, try to avoid using cold water, which can shock the plant's roots. Room temperature or lukewarm water is probably close enough to put you on the right track, but aim for water that is no more than 15 degrees colder than the current air temperature around the plant.

Peace lilies aren't fond of standing around in a puddle. Like a vast majority of plants, the Spathiphyllum genus prefers moist, well-drained soil. But it has a particular dislike of wet soil, so you should put a little emphasis on the "well-drained" part of that guidance. The problem is that we don't always have a clear idea of how to accomplish that in a pot.

Part of the issue is soil. If you choose a potting mix that retains too much water, it can exacerbate any over-watering you might do ... or even any just-right-watering you do. Stick with potting soil that has the right structure and amount of organic material to retain water (remember, you're going to be checking for soil dryness anyway), and avoid a lot of water-holding amendments.

Use a pot with drainage holes, and avoid adding other materials like gravel and pot shards to encourage drainage. The transition from soil to shards can actually inhibit drainage, but a bigger issue might be the fact that drainage material takes up too much space. There is already a certain zone of soil at the bottom of the pot that will be too wet for a peace lily's roots to use (it's called the perched water table, in case you're ever on a trivia show), so combining that with drainage material can leave your peace lily with far less root room than you thought.