One of the factors that determines whether a plant is an annual--a plant that lives for just one year--or a perennial--a plant that lives for many years--is the location where it is grown. If it is a location with mild to tropical winters, the plants can survive outdoors all year long. If the winters are cold, the plants are killed by frost. All plants need some sunshine in order to grow, but not all need the same level of sunshine. Full-shade locations are those that have less than three hours of direct sun, with filtered sun the rest of the day. Partial shade means three to six hours of direct sun, and full sun means six hour of more or direct sun.
Impatiens (Impatiens wallerana) is also known as touch-me-not, jewel weed and sultana. It is grown as an annual in all but the tropical and subtropical areas of the country, where it is a perennial. Impatiens grows to a height of 8 to 24 inches and the same width. The plant has bright green leaves and produces flowers that can be blue deep red, salmon, orange, pink, white, striped, speckled or bicolor.
Impatiens likes a rich, moist soil and part-sun to part-shade areas, where it gets just three to six hours of sunshine a day. Hot sun will make it wilt, so in areas with hot summers, put the impatiens where it will get more shade. Impatiens is hardy in U.S. Department of Agriculture hardiness zones 4 to 10, all but the coldest zone in the contiguous states.
Wax begonia (Begonia x semperflorens) plants have stems that are succulent--parts of a plant that hold water--and grow in mounds that can be from 6 to 18 inches in height. The begonia produces glossy, oval leaves that can be green, mahogany, bronze, red or variegated and flowers that can be single or double--flowers with extra petals--and red, pink, rose or white. Most varieties like full sun to part shade, but there are varieties that prefer full shade--less than three hours of direct sunlight a day, with filtered sunlight the rest of the time. Wax begonias grow as a perennial only in zones 9 to 11, the two hottest zones in the contiguous United States and in Hawaii. In all other zones, the begonia grows as an annual. Begonias can be dug up in the fall, planted in pots and brought inside.
Nasturtium (Tropaeolum majus) is a perennial in zones 9 to 11 and an annual in other zones. The plant produces circular leaves that have a deep green color with lighter colored veins that grow as large as 4 inches across. Some varieties have variegated leaves. Different varieties grow in different ways as well. Some grow in mounds, and some trail along the ground. The flowers grow to more than 2 inches wide, and the colors can be red, yellow, orange and cream and either brightly or pastel shaded. Nasturtiums do well in partial shade but do appreciate a bit of sunshine. The trailing nasturtiums do well as a ground cover under tress where they will get defused sunlight most of the day.