That White Buildup On The Outside Of Your Houseplant Pots, Explained

If you've been tending to your favorite plants for a while—particularly those in terra-cotta planters—you may have noticed a chalky, white residue forming on the outside. Don't worry; it's no cause for alarm. And thankfully, it can be prevented if you're not into the rustic look. Here's why it happens, plus what to do about it.

According to Kierslyn Kujawa, Earth's Ally brand ambassador and plant influencer behind PlantedinPots, this white buildup is the result of a combination of the kind of planter you have and the water you're using to water your plants.

"As the porous material that the planters are made of wicks away excess moisture from the plant," she explains, "it leaves behind minerals that are in your water." (If you're using tap water to water your plants, there are likely trace amounts of salt and other minerals in it.)

This happens because certain porous materials, like terra-cotta, "breathe" out excess moisture, leaving the residue on the outside of the planter. If there's enough moisture for an extended period, mold can even form (which will look fuzzy, as opposed to chalky).

But Kujawa assures mbg, "The white stuff on the outside of planters is typically no reason to panic." And if the look doesn't suit the aesthetic you're going for, here's what to do.

One option, of course, is to invest in planters that aren't porous, and instead go with impermeable options such as glass or ceramic. But if you love the look of your terra-cottas, you can also spring for a clay sealant, or water seal, that can be painted directly on the pot, to help moisture from escaping.

Another option is to use distilled water or rainwater, to prevent unwanted minerals and salt from getting into your precious plants' soil. Some plant experts will recommend letting tap water sit overnight, to help some of those minerals dissipate, but your best bet would be to go for distilled. And if mold is becoming an issue, you might want to give your plants a little more time between waterings.

And not for nothing, it doesn't take much to scrub the residue away if that's the easiest option for you. Simply remove the plant from the planter, make a solution of water and white vinegar, and use a coarse cleaning brush to scrub it away. Easy-peasy!

While mineral buildup is not harmful to your plants, you might not love the look of it. In that case, opt for distilled water, or just give your terra-cotta planters a quick scrub whenever needed—they'll be looking good as new.