Sometimes less is more and sometimes more is more. While three pots can make a corner of a deck look fabulous, 33 can be stunning too. It depends on your space and budget. However, there are a few things to keep in mind when grouping pots (though the first thing to remember is that there are no rules except to do what pleases you).
Odd Numbers Look Right
When it comes to plants in pots or groups of pots try to go for an odd number. It just seems to look better.
While these pots are different in color, they are similar in style and the colors compliment each other. Also, each pot is set on a wrought iron plant stand, which helps unify the arrangement. Using terracotta pots in different sizes a grouping is a sure-fire way to get a unified design. Keeping one variable the same is one way to think about it—either color, size or shape—can also help your design to be harmonious.
Mix Pot Sizes
This is a group of succulents on the staircase out my back door. I grouped the three small pots (two teacups and a clamshell) filled with succulents. I put them next to a medium-sized pot and then turned a tall narrow pot, upside down, and placed a pot with a draping plant on top of the inverted pot. This way your eye can travel from the lowest to the tallest. This group works because of the midsized pot. If the teacups were against the larger pot, it wouldn't work as well.
Pots at Longwood Gardens
If you ever get the chance, the pots and combinations at Longwood Gardens in Kennett Square, Pennsylvania, are some of the most extraordinary we've ever seen. Notice how they used very different pots, and used plants in each pot that are a salmon color as well as a deep wine. The textures in all the pots are quite different, but the color echoes make them form a coherent design.
Some of the most successful and formal groupings of planters are achieved by making identical planters and repeating them. The visual impact is great and depending on the planters and the plantings the effect can be very modern or more traditional. These ivy baskets are perfect for this building at Longwood Gardens. Also using repeating planters on staircases or walls or to line driveways or pathways can look amazing.