Do Rocks at the Bottom of Planters Actually Help?

Should You Put Rocks at the Bottom of a Planter?

Putting rocks in the bottom of a planter is a bit of a hot topic in the houseplant world. The theory behind the myth comes from the idea that adding rocks to the bottom of a planter will prevent root rot and counteract the adverse effects of overwatering.

However, Laura Janney, gardening expert and founder of The Inspired Garden, explains that rocks at the bottom of a planter can do more harm than good to your plant's roots. "Instead of helping with drainage, a layer of rocks, or any different material that is not absorbent, creates a zone of saturation that slowly creeps toward the top of your container," she says.

So, every time you water your plant with rocks at the bottom, you are raising the container's water table. This means your plant's roots are left sitting in saturated soil that never dries out, which leads to root rot. "Rocks or no rocks, if there is water sitting in the bottom of a planter, the plant is in danger of root rot," says Ruth Carll, Rutgers State program leader for consumer horticulture. "This health issue isn’t caused by the substrate, rocks or soil, but rather it is caused by standing water."

She notes that salt builds up in this water and creates an overall toxic environment for the roots. This is also why you should empty any standing water in your plant's saucers. The only reason to put a rock in the bottom of the planter is to cover the drainage hole and keep soil from coming out when you water your plant. Only use one rock per drainage hole.

The best way to prevent root rot is to choose a planter with a drainage hole. Drainage holes in planters allow excess water to escape. But we get it: sometimes you find such a beautiful hole-less planter that you can't help but want to put a luscious green plant inside. If that's the case, there are workarounds you can try. You shouldn't put rocks at the bottom of a planter. If your pot doesn't feature a drainage hole, you can drill one, use the two-pot method, or add a layer of activated charcoal to the bottom. Source