Have you ever stood in the nursery aisle staring at those black plastic pots, wondering what size they are? Up close, most of them appears to be the same shape. The tags say next to nothing and they often have missing information because they is faded or torn off. You want a good-sized rose, but how do you tell which one came in a large landscape container instead of just a small starter can? Such is the picture puzzle.
The chart above shows how diameters and heights varies among trade sizes. It’s your quickie cheat sheet. It prevents you from buying a giant pot for a little shrub you thought was a better deal, and it prevents root rot. But name itself perpetuates the nursery’s greatest myth. You don’t get a gallon for your dollar here; it holds less than three-quarters of a U.S. Liquid gallon, about zero point seven gallons.
How to Choose the Right Plant Pot Size
That difference add up; and affects how much soil you need to fill those pots. Plan on filling each container with as much soil as its label claims, and you’ll be out of mulch by mid-season. See the difference? The littlest, barely a-gallon herb has far less soil than the biggish fifteen-gallon tree. And size of the pot keeps growing much faster then a steady rate. Don’t expect that.
Sometimes label’s gone; then it’s the rim that will help. The rim is about six and a half inches for a small one-gallon pot, or nearly eighteen inches across on a massive fifteen-gallon tree container. That tells you how much root ball there must be inside which allows you to guess.
If you get a tiny can with a tight little root ball in it: right; the thing is primed to thrive. Lots of empty space in an oversized pot, and an airy crown: Maybe the grower got in too much hurry? Or maybe you’re shelling out money for…empty air.
Smaller is where it’s at on retail shelves. Small is mighty: nearly half of all purchases are in that little one-gallon can size. Next come two- and three-gallon sizes. Makes perfect sense. Who doesn’t want a few starter plants for filling in the garden inexpensively? But the price is different story. The larger containers gets the bigger dollars. Typically they will have older (more mature) things inside them. Get the picture? That’s why you’ll find so many small plant at nurseries, they sell lots of each, but biggies make the most money per item.
Most home gardeners fail to understand art of upsizing. When you jump directly to a giant container from a little starter, you’ll drown those roots in unused, wet soil. Follow the visual timeline of a gradual progression to bigger and bigger pots over the years, moving from the plug tray to the one gallon can to a big shrub pot. Roots is able to explore more territory at each step; they aren’t sitting in soaked media. Slow, yes; effective, absolutely.
Water it in when you bring it home, right up to the point where it stops draining out of drainage holes. That way all the rootball gets soaked. No need to replant into any old, soggy soil that may have been in its former container, this will become compacted and suffocate emerging roots. And don’t bury crown; keep it at its original soil line. This will help prevent rot and other diseases, and it will also help make sure your investment lasts longer than if you brought it home.
Pot choice can be difference between a thriving garden and a graveyard of dead plants. Match the root system to the container. Do not do it the other way around. If it’s a tight fit in a little bigger pot, it will grow out. If it has a loose fit in a huge one, it will rot.
The chart shows the measurements. You use your judgment; your eye does the rest. Check the rim; look for fullness. Keep in mind that bigger isn’t necessarily better. It’s about giving the roots enough room to breathe. Don’t strand them in unused, dry dirt. Go big, go home. Start small and go slow. And your garden will flourish.