Consider each pot a mini garden, and choose the contents accordingly. "A single type of plant gets a little monotonous," says Roger. "I like to mix lots of things together." Not just colorful annuals, either. "I'll work in perennials like a gold hosta or an ornamental grass," he says. "Then, in the fall, I'll remove it and plant it in the garden."
How to design a pleasing arrangement in a pot? Place taller plants, like sword-leaved phormium, larger delphiniums, or even a small tree, in the center of the container. Fill in around the central elements with "fluffy" plants like scented geraniums, nemesia, and double impatiens. Along the edge of the pot, install trailers like hybrid vincas or lobelia, or trailing vines like sweet potato, which can cascade over the side.
Test-drive colors and combinations by mixing and matching plants right at the garden center in the early spring. "You'll see what you like and don't like that way," says Roger. "It's much easier to return things to the shelf before you've hauled them home."
Shown: Snapdragons and dianthus spill over the edge of a weathered terra-cotta urn. below: An old stone trough makes a distinctive container for a cottage-style combo of violas and loosestrife.