How and When to Water Houseplants

Why Houseplants Need Water

If you do an online search for “the number one reason why houseplants die,” you’ll see that just about every top result points to a single culprit: overwatering. If you’re blushing with recognition right about now, you’re not alone.

First, let’s talk about why houseplants need water in the first place.

• Photosynthesis, the process during which plants make their food from the sun’s energy, requires both water and air to create the glucose that provides energy to the plant. 
• Water helps transport the nutrients and sugars produced by photosynthesis, as well as nutrients from the soil, to every part of the plant.
• Water evaporates through the leaves (in a process called transpiration) to help keep the plant cool. 

Plants are up to 95 percent water, and that water is key to strong, healthy cell structure.

Overwatering vs. Underwatering

So, all of this may leave you thinking, since water is so important, more is better, right? Not quite.

• Too much water can prevent oxygen from moving through the soil to reach the plant. 
• If that happens, roots may begin to rot and, ironically, can no longer deliver the moisture the plant so desperately needs. 
• Eventually, the roots will die—and the plant along with it. 

Of course, there’s also such a thing as underwatering (also called, let’s face it, forgetting to water). Without moisture, all the important processes mentioned above can’t happen. The result? The plant stops growing, the leaves turn dry and brown, the stem becomes brittle, and the plant will eventually die. 

Houseplants can be especially susceptible to underwatering in the summer when they’re growing faster, there’s more light, and the surrounding temperature is higher—all of which translates into water disappearing more quickly from the soil through use and evaporation.

How to Tell if You’re Overwatering or Underwatering

• Signs of overwatering include droopy and/or yellowing leaves, leaves (even young ones) that fall off, mushy-feeling stems near the base of the plants, and soggy soil. 

• Signs of underwatering include leaves that droop (but perk up after watering), turn brown, begin to curl, and/or even get a bit crispy. You may also notice a gap between the dry soil and the inside of the pot.

How to Water Your Houseplants Just the Right Amount

Lots of people water their indoor plants every week on the same day, but while that may make it easier to remember, it’s not the best approach for your plants. 

See, your houseplants don’t all use water at the same rate. Some may be thirstier than others, depending on the size of both the plant and pot, the amount of sun it gets, whether or not it’s actively growing, how hot and dry the room is, etc. That being said, it’s fine to choose one day a week as the check-in-on-your-plants day to see if they need watering!

Fortunately, the best way to ensure your houseplants get the right amount of water is the same.

1. Every few days, stick your finger into the soil. Generally, if the top inch of potting mix (two inches for succulents) is dry, it’s time to water. You can also lift the pot to feel how heavy it is–if it feels oddly light, it’s time to water.
    
2. Using room-temperature water (not too cold!), water the soil evenly around the base of the plant until water begins to run out of the drainage holes in the pot—make sure you have a saucer underneath. (If there are no drainage holes, water until the soil is well moistened, then switch to a pot with holes the next time you repot in containers.)
    
3. It’s fine to use tap water, but if you live in an area with heavily chlorinated water, let it sit out uncovered overnight before using it to allow the chlorine to evaporate. Better yet, use water from your rain barrel.

See? It’s a pretty straightforward path to keeping your houseplants happily hydrated. Now, what about keeping your green friends nourished with food? See advice about how and when to fertilize houseplants. 

For more expert advice on growing houseplants, check out our Tips for Keeping Indoor Plants Happy and Healthy Year-Round.