Heavy shade, also known as full shade, is an area that is shady all day. Gardeners find shade tricky to deal with, as few plants thrive without light, and soil in shady areas can be wet. But there are several tried-and-true annual shade plants, including coleus, caladium and violets, which can add color to any shady area.
Coleus (Coleus hybridus) is technically a perennial but is planted as an annual in many regions. Native to the tropics, coleus has colorful leaves in shades of green, yellow, chartreuse, salmon, red, orange, purple or brown, and leaves often have some combination of colors. This plant also has a small blue flower spike that is often pinched back to maintain focus on the leaves. Coleus can grow in all zones, thrives in full or partial shade and grows to about 2 feet.
Selected as the 2009 National Garden Bureau annual of the year, flowering tobacco (Nicotiana alata) has showy, trumpet-shaped blooms in red, pink, purple, green or yellow. Foliage is sticky and hairy. Plant flowering tobacco after last frost and it will grow to about 18 inches. Blooms on most varieties lack scent, though the Perfume and Saratoga varieties have fragrance in the evenings. These plants prefer shade in the deep south.
Caladium (Caladium bicolor) is native to tropical parts of the U.S. This plant has large leaves similar to those on elephant ears, though the green leaves are marked with stripes or blotches of white, red, pink, silver, bronze or green. Leaves may be as long as 1-1/2 feet. A perennial in the south, caladium is a shade lover that grows to about 2 feet and thrives in humid regions with rich, wet soil. Caladiums die back when the temperature drops below 60 regularly, but roots can stay in the ground in the warmest regions, like south Florida, all year. In cooler areas caladium is an annual, and the tuberous roots may be dug up and stored for the winter.
Violets (Viola) are a member of the Violaceae family, which also includes violas and pansies. Most often found in woody or rocky gardens, violets have heart-shaped flowers and are usually purple, though some sweet violet (Viola odorata) varieties are available in white or pink. In cooler areas, violets may become invasive. These plants need regular water.