The Planter Size Guide

Planter sizing trips up almost everyone, because pots are sold by diameter but plants care about volume. This page is the reference we wish came stapled to every pot: what each size actually holds, what tends to live happily in it, and the one rule that prevents most repotting disasters.

The one rule that matters

When you move a plant up, go up by one size only: 1 to 2 inches wider for pots under 10 inches, 2 to 3 inches wider for larger pots. A small root ball in a huge pot sits in wet soil it cannot drink, and wet soil without roots in it is where rot starts. If you are unsure between two sizes, take the smaller one.

Planter size chart

Volumes assume a standard-proportion pot, roughly as tall as it is wide. Bowls hold less, tall cylinders hold more. When a bag of potting mix says 8 quarts dry, expect it to settle; buying about 20 percent more than the chart says is the comfortable margin.

Signals it is time to size up

• Roots circling the surface or poking out of drainage holes.
• Water runs straight through in seconds, because roots have replaced most of the soil.
• The plant dries out much faster than it used to on the same schedule.
• Growth has stalled during the growing season despite decent light and feeding.

Two or more of those together is a yes. One alone is a maybe; check the root ball before committing. Our guide to repotting without killing your plant walks the whole process step by step.

Nursery pots vs decorative planters

The plastic nursery pot is a growing container; the pretty pot is furniture. Keeping plants in nursery pots slipped inside decorative cachepots gives you drainage, easy repotting, and the freedom to change looks in ten seconds. If you plant directly into the decorative pot, it must have a drainage hole. No exceptions that end well; our piece on drainage holes explains why.

Get a number for your plant

The planter size calculator takes your current pot diameter and plant type and returns the next pot size, the soil volume you will need, and a rough cost for the upgrade. For choosing material, our terracotta vs plastic vs ceramic comparison covers the trade-offs.