Summer plants that need full sun are those that require at least six hours of sunlight each day to perform their best. Pay attention to how the sunlight moves through your landscape throughout the year and consider shade cast by large trees and shrubs as they grow. Plant perennial flowering plants for a garden that comes back year after year, or choose annuals that are replaced at the end of the growing season. Some perennial plants that are too tender for cold climates are treated like perennials and replaced as necessary.
Grow shasta daisies (Laucanthemum x superbum hybrids) for their cheerful white blooms that are well suited to mixed borders or for cut-flower arrangements. Shasta daisies grow easily in sunny locations with moist, well-drained soils. Cultivars include 'Alaska', a daisy with single, white, 3-inch flowers that grows up to 3 feet tall, and 'Silver Princess', a 12-inch bushy shasta daisy. Shasta daisies are perennials and grow in zones 5 through 10, depending on the cultivar.
Sunflowers (Helianthus annuus) are often grown for their spectacular flowerheads that turn to follow the sun during the day. They provide a powerful punch of color to a summer garden. Sunflowers prefer open, full sun locations, and nutrient-rich, moist, but well-drained soils. 'Ring of Fire' has fiery blooms of yellow and brick red, and grows 3 to 5 feet tall. 'Strawberry Blonde' is a rose-pink sunflower growing 6 feet in height. Sunflower cold hardiness varies by cultivar, ranging from USDA zones 4 through 11.
Hollyhocks (Alcea rosea) are old-fashioned cottage garden plants 2 to 7 feet in height, depending on the cultivar, and produce tall stalks of flowers ranging in color from white, yellow, pink, apricot or purple. They prefer full sun and well-drained soil. Hollyhocks are hardy in zones 5 through 9.
Zinnias (Zinnia elegans) are rapidly growing, herbaceous annuals, often with pompom-like flowers, and range in height from 7 to 36 inches tall, depending on the cultivar. Zinnas are found in every color except blue and some are multicolored. Grow zinnias in full sun on various soils. They are useful as bedding plants, in containers or as cut flowers for arrangements. Zinnias are hardy in zones 8 through 11.