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Best Self-Watering Planters for Patios

A self-watering patio planter keeps a reservoir under the mix, so you fill a tube instead of watering the surface every hot day. EarthBox is that kind of box. This page sums up how they work in general. It was not a hands-on test.

EarthBox Container Gardening System on Amazon

Terracotta-colored rectangular planters on a wooden porch, with black fill tubes rising from the soil. — Planters with fill tubes on a porch. This shows the kind of reservoir planter the page is about. They are not an EarthBox. Photo by GreenFrieda, CC BY-SA 4.0, via Wikimedia Commons. The file’s credit line reads Lechuza.

How it works

A water reservoir sits under a platform or screen at the bottom of the planter.
Part of the potting mix reaches down into the water and wicks moisture up to the roots.
You refill through a fill tube. An overflow hole at the top of the reservoir lets extra water, including rain, drain out.

Why it helps on a patio

Pots in sun and wind dry out fast, and a reservoir gives you a buffer between waterings.
Watering through the tube keeps leaves dry and the surface from crusting.
Thirsty crops such as tomatoes, peppers, cucumbers, and leafy greens do well with steady moisture.

What to watch for

Use potting mix, not garden soil. Garden soil packs down and wicks poorly in a container. See soil for bagged potting mixes.
Keep the overflow hole clear, or heavy rain can waterlog the roots.
Check the reservoir in hot spells. It stretches the time between waterings but doesn’t remove the need.
Mind the weight. Water weighs about 8.3 pounds per gallon, on top of wet mix. Check what a balcony can carry before placing a large planter.
Skip plants that like to dry out, such as succulents and rosemary. Constant moisture doesn’t suit them.