Containers are as varied as the plants that are available for them. Plants should be scaled to the size of the container, with the tallest plant being about twice the height of the container. All plants in the container should have matching soil and climate needs.
Ornamental grasses are a bold statement in a container and are available in a variety of heights. Big bluestem (Andropogon gerardii) is one of the tallest of the ornamental grasses, reaching a height of 3 to 6 feet. It grows in a stiff, upright clump of and has blue green foliage. Blue grama (Bouteloua gracilis) grows to a height of 1 to 1.5 feet. It does best in full sun. Blue oat grass (Helictotrichon sempervirens) grows to a height of approximately 2.5 feet. The grass grows in full sun to light shade. It has pointed blue leaves that grow in tufted clumps. The seed heads appear in June. Starting out white, they eventually turn a golden color.
Woody plants can add an unexpected contrast to larger containers. Choose a plant that is easily pruned to keep the size in balance with the container. Woody plants that can be sculpted into shapes will only add to the originality of the container garden. Dwarf Alberta spruce (Picea glauca "Conica") is a pyramidal evergreen shrub that can be pruned to go nicely in a large container. It grows slowly and likes full to partial sun. Japanese Maple (Acer palmatum) are often grown as Bonsai and are striking in a container. They have seven-palmed leaves of green or red that turn to bright yellow or orange in the fall. The Japanese maples have multiple trunks. The Japanese Maple grows to be 10 to 12 feet high, so plan to increase the size of the container.
The astilbe hybrids (Astilbe x arendsi) grow to a height of 2 to 4 feet. Feathery spikes of pink, red, white or salmon flowers appear in midsummer. The rose-like leaves make the astilbe attractive at times the plant is not in bloom. Astilbes grow best in containers that receive partial shade, with the container having a diameter of at least 1 foot. Daylilies need a container at least 16 inches deep and with an 18 inch diameter. The sword shaped leaves of the daylily will be just over 2 feet, but the blooming stalks can reach 3.5 feet. Plant the daylilies in the full sun. Once planted, they need little attention.