Roses should be planted in early spring as soon as the ground is thawed enough to be worked, according to the University of Illinois. With more than 150 species in the Rosa genus and thousands of cultivars, most home gardeners have an easy time finding a favorite rose to plant. Most grow in bush form. Miniature roses are tiny and are often grown in containers. Climbing roses have long canes that need to be supported. Some roses have a strong fragrance, while others have none. Roses have single petals or are heavily ruffled, and the blooms can range from just one giant flower to many flowers balanced atop one stem. All roses thrive in rich, well-draining soil and in full sunlight.
Snapdragons (Antirrhinum majus) are an annual flower, which means they must be planted year after year. These colorful border plants are easy to grow and thrive in cool climates. They can even tolerate light frosts, according to the University of Arkansas. Plant them in early spring when the soil is still cool. Snapdragons grow best in full sunlight and in soil that drains well. Deadhead (remove) spent blooms to encourage reblooming.
Pansies (Viola spp.) are another cool-season annual. These small, cheerful flowers, which come in an astonishing array of colors and sizes, thrive in the cool weather of spring. In the northern states, they should be planted in early spring, but they can be planted in winter further south. Pansies are extremely cold-hardy. They can freeze, and then thaw out and continue blooming, according to the University of Arkansas. Plant them in full sun or partial shade in moist but well-draining soil. They will bloom until it gets too hot, at which point they will wilt, fade and need replacing.
Lilies (Lilium spp.) are hardy flowering bulbs. They are easy to care for, according to the University of Minnesota, and can be planted almost any time of the year, including early spring. In fact, many home gardeners stagger their plantings so that they will have lilies blooming from May through September. Plant lily bulbs in the spring when the ground can be worked, but place a 4-inch layer of mulch over the planting site to protect against hard freezes. Once the shoots emerge, you can gradually remove the mulch. Lilies grow best in full sunlight and must have well-draining soil. Too much water in the soil will cause the bulbs to rot.