Growing flowering annuals from seed in the garden takes a little more patience than growing flowers from transplants, but it isn't difficult if you pick the species that grow quickly and dependably from seed. Mary McLellan, Extension Master Gardener program coordinator at Michigan State University, said gardeners looking for success with flowers from seed should try the following:
— Sunflowers. Large seeds are easy to handle and quick to germinate and grow. A great variety of plant sizes, flower sizes, and flower colors is available. The tallest may reach 10 feet, with flowers up to a foot in diameter. Others offer multiple flowers per stem, and some are great for cutting. As the name implies, sunflowers do best in full sun. They also tolerate heat and drought.
— Cosmos. Sow seed directly into the garden after the danger of frost is past and thin seedlings to 12 inches. The daisy-like flowers come in shades of pink, lavender, scarlet, and dark red, as well as white and yellow. Plants usually reach a height of three to four feet, though dwarf varieties growing to 12 to 14 inches are also available. Cosmos needs full sun and tolerates heat and dry weather.
— Hollyhocks. These old-timey flowers thrive in hot, direct sun and produce their spikes of single, semidouble, or fully double flowers in a wide range of colors. Most varieties are two to four feet tall, so they're often used as background plants in beds and borders or grown in front of evergreens, fences, or walls. Plant after the soil has warmed up in the spring and thin to 12 inches. Hollyhocks planted in spring will bloom this summer; those planted later in the year may wait until next year. Hollyhocks will reseed themselves, though not necessarily where you expect them.
— Marigolds. A wide range of plant and flower sizes and types is available with flower colors ranging from whitish through golden yellow and orange to brick-red. Marigolds are among the quickest annuals to flower from seed sown in the garden - some varieties take only five to six weeks. And marigolds generally keep growing and flowering all summer. Plant in full sun after the danger of frost is past.
— Zinnias. It's hard to beat zinnias for beds, borders, or cut flowers. A variety of plant and flower sizes, flowers in almost any color you might want (except blue), and varieties with multicolored flowers make zinnias a colorful choice for the sunny garden. Quick to bloom from seed and easy-care, zinnias respond to cutting by growing bushier and producing more flowers. They thrive in heat and full sun. Powdery mildew can be troublesome, particularly in late summer and early fall. Plant in full sun in an area with good air circulation and avoid overcrowding and overhead watering to minimize mildew problems.
— Sweet peas. Like garden peas, sweet peas can be planted outdoors as soon as the soil is dry enough to work. Both climbing and bush-type plants are available, with fragrant flowers in white or shades of pink, rose, lavender, and red. Look for varieties with good heat resistance - they'll last longer into the summer.
— Nasturtiums. Another long-time garden staple, nasturtiums thrive in dry areas and poor soil. Too-rich soil or overfertilizing will produce lush plants with few flowers. Bush, climbing, and trailing varieties are available. All require full sun and produce long-stemmed flowers in shades of yellow, orange, and scarlet. Both leaves and flowers are edible.
— Four o'clocks. Trumpet-shaped flowers that open in late afternoon give four o'clocks their name. Flowers are often striped in white and shades of pink, salmon, yellow, rose, or red. Sow after the danger of frost is past and expect flowering to begin in July and continue until frost. The mound-shaped plants may reach two feet in height.
— Portulaca. This low-growing plant has succulent stems that spread rapidly. Plants flower lavishly in hot, dry sites, producing their first rose-like flowers about 8 weeks after seeding. Think of portulaca (also called moss rose) as a sun-loving flowering ground cover and use it accordingly - in window boxes, beds, rock gardens, or sunny borders. Flowers may be white, yellow, pink, lavender, peach, or red; some are bicolored.
— Nicotiana. The fragrant, star-shaped tubular flowers are a big hit with hummingbirds and night-flying hawk moths. Colors range from white, pink, and lime green to dark red and light yellow. Nicotiana thrives in humid areas and partial shade as well as full sun. It reseeds itself and so tends to come up year after year without replanting. Grow from seed sown in the garden after the danger of frost is past. Dwarf varieties grow to 16 to 18 inches; other types reach 30 inches.
