Flowering container gardens are easy to maintain. They brighten apartment balconies and accent gardens and patios. You can make them using almost any container that is weatherproof and will drain water. How to choose the right flowers for your outdoor container gardens is a matter of taste and a little shopping at the local home center. Your initial investment in container and potting medium is more than for a garden border, but you'll need fewer plants. Choose the right plants to make a noteworthy composition.
Note the growing conditions where you'll be placing the containers. Choose plants that share the same cultural requirements---sun exposure, water, nutrients---for a successful container garden. You may love zinnias and begonias, but they each require different growing conditions and would not be effective container companions.
Find flowers that cooperate or complement each other. Plant shallow-rooted annuals with deep-rooted wildflowers or spring or summer bulbs so their roots won't have to compete for water. Choose flowers of different growing heights; coneflowers or snapdragons provide tall shapes to balance heavy-leaved sedums and bushy salvias. Plant outdoor containers with dramatic canna or orchid lookalikes monkey flower and scizanthus for easy-to-maintain impact.
Choose plants for successive bloom. Most garden annuals, like marigolds and geraniums, bloom all summer long. Perennials (or perennials grown as annuals), like narcissus, tulips, asters and chrysanthemums, have specific periods of bloom. Mix flowers that bloom all summer with those that don't to create a container that changes its look with the season.
Plant flowering shrubs in large outdoor containers for architectural interest. Compact flowering varieties of shrubs like gardenia, camellias, star jasmine---even a shrub rose---can help define spaces or establish formal settings. Shrubs usually occupy containers by themselves since other plants may compete or crowd their roots.
Seek out new varieties of old classics. Every year brings new flower and leaf forms and colors for geraniums and petunias. Don't hesitate to use the standards as container plants; they are popular because they are easy to grow in containers. Add tall accents like dracaena or ornamental grasses and small plants like intense blue lobelia or lavender ageratum (with white or salmon-colored plants) or white sweet alyssum (with intense reds or purples).