The best annuals for full sun include angelonia, California poppies, cosmos, signet marigolds, sunflowers and zinnias. Alone, or combined with perennials in garden beds, they are colorful and easy to grow. Some of these annuals are also at home in containers, including window boxes.
Angelonia (Angelonia angustifolia) blooms in summer to fall with violet-blue flower spikes resembling snapdragons above spreading green foliage.
Although angelonia is an herbaceous perennial hardy in U.S. Department of Agriculture plant hardiness zones 9 though 11, it is often grown as an annual throughout the U.S. Starting with new plants each spring is suggested.
Useful in sunny garden beds, it grows to a height of 2 to 3 feet and up to 1 foot wide, and is tolerant of heat and humidity.
With brilliant orange flowers above feathery, gray-green foliage, California poppies (Eschscholzia californica) bloom in spring and summer. Growing to a height and width of 6 to 18 inches, they make a striking visual impact when planted en masse.
In addition to orange, California poppies are available in shades of red, pink, yellow and cream. 'Mission Bells' is one mix that offers ruffled flowers on plants growing 6 inches high.
California poppies tolerate dry soils and self seed.
All parts of California poppy are poisonous when ingested.
Cosmos (Cosmos bipinnatus) grows 1 to 6 feet tall, depending on the cultivar, with summer to fall flowers. The flower colors vary with the cultivar from white to pastel pinks, with yellow centers.
'Daydream,' a variety which grows to 2 to 3 feet high, offers bicolor petals in a darker pink fading to pale pink. Also tolerant of dry conditions, cosmos has fine foliage that spreads 1 to 2 feet.
Smaller and more delicate-looking than other varieties of marigold, signet marigolds (Tagetes signata, syn. Tagetes tenuifolia) have half-inch yellow, red or orange blooms in summer to fall above pungent, lacy foliage.
Although generally grown as an annual, signet marigold is an herbaceous perennial hardy in USDA zones 8 through 11.
'Lemon Gem,' 'Red Gem' and 'Orange Gem' grow to 1 foot tall and are ideal for window boxes in direct sun.
No longer are sunflowers (Helianthus spp.) simply the single yellow-faced variety on tall stalks. Now available in a myriad of heights and colors ranging from cream to maroon, there is a sunflower for every sunny garden.
'Teddy Bear' is a dwarf variety with fuzzy, gold blooms in summer, 3 to 4 inches across, on plants 35 to 42 inches tall. Planted in containers, they reach a height of only 8 to 12 inches.
Especially great for cut flowers, 'Moulin Rouge' is a branching and pollenless variety, growing to a height of 60 to 80 inches. The maroon blooms are 3 to 4 inches across in summer to fall.
Well-known for their heat-tolerance, the different varieties of zinnias (Zinnia spp.) are numerous. They range in height from 8 to 48 inches, depending on cultivar, and summer flowers come every color except blue and black.
'Crystal White' zinnia (Zinnia angustifolia 'Crystal White') is a bushy plant 10 inches to 15 inches high and can be used as edging in the front of a border. Well-known for its disease-resistance, the 'Crystal' series zinnias are also available with orange or gold flowers.
'Persian Carpet' zinnia (Zinnia haageana 'Persian Carpet'), also called Mexican zinnia, offers bicolor flowers in shades of yellow, gold, maroon and orange. It grows 12 to 18 inches tall with narrow green leaves and does well in both borders and containers.