Annual Flowers for Containers in Colorado

Geraniums

• Geraniums (Pelargonium) work well in all the Colorado environments, including being dependable wintertime houseplants. They come in pink, red and white bloom colors. The two most common types used in Colorado containers are the zonal geranium (Pelargonium x hortorum), an upright plant with scalloped or variegated leaves and tight clusters of blooms sitting high on each stem, and the ivy-leafed geranium (Pelargonium pelatum), a trailing type with waxy green, ivy-shaped leaves and small, less dense clusters of blooms. Both types are tender perennials in USDA zones 10 to 11. These geraniums are heavy feeders and prefer well-drained soil, with plenty of sunshine. They make great companion plants and look wonderful when planted with petunias (Solanaceae), herbs and other sun-loving annuals.

Petunias and Calibrachoa

• Fragrant petunias and calibrachoa (Solanaceae) are regular favorites in Colorado because they are durable, easy to grow, provide continual color, handle a light frost and provide a vast variety of hues, including pink, red, orange, purple, white and yellow. Tender perennials in USDA zones 10 to 11, both types require plenty of nutrients and full sun to keep them blooming. Calibrachoa, or million bells, has small trailing stems and blooms compared to its larger cousin, the petunia, and works best as a trailing container planting, while the petunia can perform as an upright planting or a trailing one.

Impatiens

• Among the best plants for shady areas, impatiens walleriana (Balsaminaceae) offer a vast variety of bright colors with solids and mixes in salmon, red, oranges, pink, purple and white in single or double blooms. Very susceptible to cold weather, they will freeze when wind chills dip toward freezing. A tender perennial in USDA zones 10 to 11, impatiens provide easy continual color in containers and are beautiful when planted with other shade plants such as the coleus (Solenostemon scutellarioides) and heuchera (Heuchera).

Pansies and Violas

• With or without faces is a personal preference when picking out pansies (Viola x wittrockiana) and violas (Viola) for your containers. Both species are hardy in USDA zones 6 through 10, love well-drained conditions in full sun to partial shade and come in a rainbow of colors that often continue to bloom throughout the winter in protected locations. Supply your violas and pansies with even watering, because they tend to stop blooming if allowed to dry out. Both species will reseed in the spring, offering an unending supply of new plants in gardens where pre-emergent herbicide is not used. Because of their small size, pansies and violas make great filler plants to mix into containers.