Serious gardeners plant perennials not annuals, right? Well, yes and no. They plant perennials for beauty that returns from one year to the next, but they also indulge in annuals to bring season-long color to the garden. Annuals fill in bare spaces between newly planted perennials and provide continuous color to augment the shorter bloom-times of most perennials. They supply flowers and foliage for containers, temporary camouflage on fences and arbors, and an unending upply of flowers in cutting gardens.
The easiest annuals grow successfully from seeds you sow directly in the garden. Some, like bachelor's buttons and Shirley poppies, prefer the cool soil and temperatures of early spring, but most germinate best when you sow them in warm soil, after all danger of frost has passed. Try the following five flowers easily grown from seed sown in warm garden soil.
(Cosmos bipinnatus, C. sulphureus) With gracefully filigreed foliage and pert flowers, cosmos belong in every garden. Plants grow from 12 inches to 4 feet tall, depending on the cultivar, so you can find a size suitable to a wide variety of uses and spaces, including containers. Sow seeds in full sun in rows in a cutting garden, in groups or scattered among tall perennials in a border, or in empty spaces in a container after you set in transplants of other annuals. Stake tall cosmos in a cutting garden; in a border, you can let them bend and drape gracefully in the background. Fertilize once or twice during the season if you cut flowers often for arrangements. Cosmos is fairly drought-tolerant.
Uses and Combinations: In a cutting garden, of course. Mix them with perennials or roses for an old-fashioned cottage garden design. Taller sorts belong at the back of the garden; shorter cosmos make excellent edging plants. Cosmos combines well in containers with lobelia, geraniums, poppies, Shasta daisies, and blue salvia.
Uses and Combinations: Edge beds and borders; they combine particularly well with dwarf daylilies, coreopsis, and yarrow. Plant along with tomatoes in the vegetable garden to repel root nematodes. Grow in containers and window boxes with salvias (red or blue), vinca, and nasturtiums.
(Ipomoea nil, I. purpurea [I. tricolor], I. alba) The twining stems of morning glories cover an arbor or fence with masses of heart-shaped leaves and beautiful flowers, each of which lasts for one day. The range of colors includes blue, such as classic 'Heavenly Blue', red, pink, and lavender, often combined with contrasting or deeper markings. For large, pure white, fragrant blooms, try the morning glory's relative, moonflower (I. alba), which begins to open at dusk. For best and fastest germination, before sowing seeds outdoors, soak them overnight in a damp paper towel; then, if you want, knick the rounded end lightly with a nail file or scissors. That is the only tricky part to growing morning glories. Use a sturdy support for the plants, which can become quite heavy as they quickly climb skyward to a height of 10 or more feet. You do not need to fertilize or provide extra water during the season. Plants flower in full or part sun.
Uses and Combinations: Sow morning glories and moonflowers on the same trellis or arbor for morning to evening color. Camouflage an unattractive cyclone or stockade fence: stems will climb naturally up cyclone fencing; use twine or monofilament fishing line on wooden fences.