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Choose the shape by the space it has to fill, then by the look. Square and rectangular planters give the most planting surface for the floor space they take and line up neatly against walls and each other. Round planters soften hard corners and suit a single specimen or tree. Long rectangular troughs build rows and screens, and low bowls suit shallow seasonal planting. Check the opening, not just the outside width, because some shapes are much narrower at the top than they look.
Most planters are chosen by eye, and shape is usually the first thing that catches it. But shape also decides how much soil a planter holds, how wide a root ball it can take, how it sits against a wall and how it behaves in wind. A few minutes with the published dimensions is worth more than a photograph.
Which shape gives the most planting space?
At the same outside width, a square gives more planting surface than a circle. That is plain geometry: a square of a given width has about 27 percent more area than a circle of the same width, because the circle gives up the four corners.
You can see it in two planters of the same 24 inch width. The Montroy Cube at 24 inches has a 21.2 by 21.2 inch opening, about 449 square inches of planting surface. The Lisbon Tall Round at 24 inches has a 20.9 inch round opening, about 343 square inches. Same outside width, roughly 30 percent more surface on the square.
Rule of thumbAt the same width, a square planter has about 27% more planting area than a round one.
Two other shape details change the soil volume more than people expect:
- Taper. A planter that narrows toward the base holds less soil than a straight-sided one with the same rim, because the lower part of the root zone is smaller.
- Narrow mouths. Globes and jars are much narrower at the opening than at their widest point. The Globe at 36 inches across has a 17.4 inch opening, and the Barà Jar at 24 inches across has a 14 inch opening. Lovely as sculptural pieces, but the opening limits the size of root ball you can set in them.
Every size on this site publishes its interior opening alongside the outside dimensions, so you can compare the planting space directly rather than guessing from a photograph.
Round planters
Round planters soften a space. Against the straight lines of a building, a paving grid or a deck, a curve reads as softer and more natural, which is why a round pot is the classic choice for a single specimen plant, an olive, a citrus or a clipped topiary.
"Round" covers several quite different forms, and the differences matter:
- Cylinders are straight-sided, so they hold more soil than a tapered round of the same rim width and height.
- Tapered rounds narrow toward the base, which gives a lighter look and slightly less soil.
- Bullets and tall rounds lift the planting toward eye level. The Saint Tropez runs from 32 to 60 inches tall.
- Urns, jars and globes are statement forms, chosen for silhouette, with the narrower openings described above.
For trees, the opening and the depth matter more than the style, and our guide to planter size for a tree works through both. Browse the full range of round fiberglass planters.
Square planters and cubes
Square planters are architectural. They line up with walls, steps and each other, so a pair either side of a door or a row along a terrace edge looks deliberate. They also make the most of a tight footprint, for the reason in the section above.
Cubes are the simplest version, equal in width and height. The tall tapered squares go the other way: the Toulan runs up to 60 inches tall on a 28 inch footprint, which puts planting at eye level without taking up a large floor area. For entrances, our front door planter guide covers how tall and how wide a pair should be for your door. Browse the square fiberglass planters.
Rectangular planters and troughs
Rectangular planters do the jobs a single pot cannot: a hedge in a box, a screen along a boundary, a row of herbs along a railing, a division between two parts of a terrace. The range we carry runs from 24 to 100 inches long and from narrow boxes 7 to 10 inches deep, which fit along a walkway, to troughs 24 inches deep for larger planting.
Long runs raise their own questions, such as whether to use one long planter or several shorter ones, and how much drainage each needs. Our guide to one long planter or several covers that, and the privacy screen guide works out how tall a screen needs to be. Browse the rectangular fiberglass planters.
What is a corner planter?
Despite the name, a corner planter is not L-shaped or angled. In the Jay Scotts ranges, the corner planter is the square box within a series, made to stand in a corner or to finish the end of a run of the matching rectangular planters at the same height. That makes it easy to wrap planting around a corner with one consistent look. Browse the corner planters.
Low bowls
Low bowls are wide and shallow, so they put the planting on show rather than the planter. The Casablanca, for example, runs from 20 inches across and 10 inches tall to 36 inches across and 18 inches tall. Their limit is depth: they suit shallow-rooted, low or trailing planting and seasonal displays, not shrubs or trees. Browse the bowl planters.
Do plants grow better in square or round pots?
For the plant, shape matters less than size, depth and drainage. The one measurable difference is in how roots behave against the wall. In a nursery study published in the Journal of Environmental Horticulture in 1991, Warren and Blazich grew azalea, holly, juniper and viburnum in several container designs and found that square, stepped and bag containers significantly reduced root circling compared with a traditional straight-walled round container. They also found that no single design was consistently better for top growth over two years.
So a square shape has a small edge on root circling, but a planter of the right size, with drainage, matters far more than its shape.
Which shape for which spot
| Spot | Shape that usually works | Why |
|---|---|---|
| Front door | A matched pair of square or tall round planters | Frames the door and reads as deliberate |
| Narrow walkway or railing | Narrow rectangular | Planting length without blocking the path |
| Privacy screen | Tall rectangular | Continuous height along a line |
| A single tree | Large square or round with a wide opening | Room for the root ball |
| Rooftop or exposed terrace | Low and wide | Harder to tip than tall and narrow |
| A corner | Corner or square planter | Fills the corner squarely |
| Tabletop or accent | Low bowl or small cube | Shows off the planting |
On a roof or an exposed terrace, weight, access and wind come before shape. Our rooftop planters guide covers all three.
Can you mix shapes?
Yes, and grouped planters often look better for it. The trick is to keep one thing constant so the group reads as a set: the same finish across different shapes, or the same shape in different heights. A tall round beside a low square in the same color looks planned; three shapes in three colors can look accidental.
Most of the Jay Scotts planters we carry are finished to order from the same range of colors, which makes it easy to match a round, a square and a trough in one finish.
Shop the collection
Fiberglass planters in every shape
Round, square, rectangular and corner, with the interior opening published on every size.
Frequently asked questions
What is the best shape for a planter?
The one that fits the space and the planting. Square and rectangular planters give the most planting surface for their footprint and line up neatly; round planters soften a space and suit single specimens; low bowls suit shallow seasonal planting.
Do plants grow better in square or round pots?
Shape matters less than size, depth and drainage. A 1991 study in the Journal of Environmental Horticulture found square containers reduced root circling compared with straight-walled round ones, but no design was consistently better for growth.
Does a square planter hold more soil than a round one?
At the same width and height, yes. A square has about 27 percent more area than a circle of the same width, so it holds more soil.
Can you mix square and round planters?
Yes. Keep one thing constant, such as the finish or the height, so the group reads as a set rather than a collection of odd pieces.
What is a corner planter?
A square planter made to stand in a corner or finish a run of matching rectangular planters. Despite the name, it is not L-shaped.
Does a tapered planter hold less soil?
Yes. A planter that narrows toward the base holds less soil than a straight-sided one with the same rim width, because the lower part of the root zone is smaller.
