March 1 2004 12:00 AM

Painting the landscape with colorful flowers may seem easy enough, but bedding plants can present some problems, too. There?s nothing attractive about a bunch of wilted plants on a hot summer afternoon. And what may look like a gorgeous splash in the landscape on Friday may turn to slimy brown mush greeting you on Monday morning. And who hasn?t taken a second look at a growing tip only to find that it is covered with what seems like millions of aphids?

Fortunately, with a little planning, these problems can be reduced or even eliminated. Most bedding plants need rich, loose soil; flower beds benefit from generous use of well-incorporated organic amendments. Good drainage is a must. Regular light fertilization and evenly moist soil will also keep plants pumping out the blooms.

Let?s take a look at some of the more popular choices for annual flowers, from A to Z. Unless noted, these all love full sun.

Ageratum (Ageraturm houstonianum), also known as floss flower, is great for edging a bed. The slightly hairy, soft green leaves are a pleasing background for the blue, fluffy flowers. There are also pink and white varieties available. The plants make a nice neat mound, anywhere from four to 10 inches tall, and as high.

Amaranth (Amaranthus caudatus) is as tall as ageratum is short. This plant grows rapidly, reaching three to six feet. Also known as tassel flower or love-lies-bleeding, the unusual flowers hang below the large leaves like fuzzy ropes of red or golden green. It thrives on heat. Its relative, A. tricolor is grown for its showy leaves, ranging in shades of red to copper to gold.

Asters (Callistephus chinensis) are a wonderful old standard; you can plant a flag with the red, white and blue flowers, or opt for softer shades of pink and purple. Dwarf plants a foot tall or less are good for edging, while taller varieties are great in mixed borders and for cutting.

Begonias are also a popular choice, especially the wax begonia (Begonia x semperflorens-cultorum). Begonias bloom almost nonstop in white, pink or shades of red. The leaves also range from bright green to bronze. Begonias are especially useful because they will tolerate shade and still produce a floral spectacle. Technically, they are perennials, and can be carried over in warm climates if desired.

Browallia (Browallia speciosa) can also grow in shaded locations. Also known as amethyst flower, this heat-lover offers small bell-shaped blue or purple flowers (although there are also white varieties). Browallia does great in containers or hanging baskets, as well as mass plantings.

(Calendula officianalis), is an excellent choice for any landscape where bright orange or yellow flowers are appreciated. Breeders have also produced softer shades of cream and apricot. Growing from 12-20 inches, depending on the variety, it thrives in all but the hottest locations. A tasty bonus is the edible flower petals, which can be used as a garnish in salads or brewed into tea.

Celosia (Celosia cristata) comes in two basic types. The plumed type has feathery, upright flowers in hues of red, yellow, orange, cream and shades in between. This year, All American Selections (AAS) honored two plumed celosias: Fresh Look Red was the floral gold medal winner, while Fresh Look Yellow also won an award. Crested celosia forms tight heads with wavy edges, looking something like a cockscomb (although we used to call them ?brain flowers? because of the way the tops looked.) Of the two, plumed celosia seems easier to grow.

Cleome (Cleome spinosa) is an easy-to-grow tall plant with massive, spidery flowers that top the three to five foot stems. In fact, it is often called the spider flower because of the shape of the flowers, which can be up to six inches across in rose or white. A favorite in old-fashioned gardens, cleome loves extended warmth and is great as a background for other flowering plants.

Although it isn?t grown for its flowers, coleus (Coleus x hybridus) is perfect as a summer annual for shady spots that need a splash of color. Its leaves range from the deepest red to the brightest yellow ? sometimes all together! If the insignificant flowers should appear, pinch them off to extend the life of the plant.

Cosmos is a favorite of finches when it goes to seed. The delicate leaves of Cosmos bipinnatus, known as garden cosmos, make the plants look airy, and the daisy-like flowers come in pink, violet, white and maroon. They can grow up to six feet tall, and might even need staking to hold up the big blooms. C. sulphureus flowers in shades of yellow and orange, with leaves that are coarser than garden cosmos, and the plants are shorter and more dense. Cosmic Orange was a 2000 AAS winner. Both varieties make long-lasting cut flowers.

Dahlias are one of the most diverse of flowers, available as the tiniest button flowers or ?dinner plate? types. The colors as well come in a rainbow of hues, featuring just about every shade but blue. Bedding dahlias are started from seeds, and the smaller varieties are perfect for edging. The larger types can grow up to six feet, and make a wonderful background for floral borders. If desired, the tubers formed by the root system can be lifted at the end of the season and stored for use the following year.

Gazania (Gazania rigens) is a Southwest favorite, as they love hot, arid climates. The daisy-like flowers are white, cream, orange and yellow; usually the centers contrast with the edges. Gazanias can be perennial in mild winter areas, but will die early if humidity is high.

(Pelargonium spp.) are also a classic garden accent for good reason. P. x hortorum, or the bedding or zonal geranium produces vibrant, show-stopping flower clusters in red, white, pink, orange and all shades in between. The soft, slightly hairy foliage can be bright green or variegated with darker green or a reddish tone. They are great planted in masses. Its cousin, P. peltatum, is known as ivy geranium and is a perfect choice for hanging baskets ? or even as a ground cover. In mild-winter climates, these plants are perennial.

Impatiens (Impatiens wallerana) are made for the shade . . . especially when summers are hot. They are the most widely sold annual of all, for good reason. Easy to care for, everblooming, tidy and beautiful, impatiens look great planted in masses. There are many different varieties; breeders have produced large flowers which ?self-clean.?

Who doesn?t love marigolds? The two most commonly planted species, Tagetes patula and T. erecta, offer a long, dependable blooming season. Newer varieties drop the flowers before seeds form, eliminating the need for ?dead-heading.? T. patula, the French marigold, grows to one foot or less, with flowers about one to two inches across ? great for edging or containers. T. erecta generally grows two or three feet tall, and boasts showy flowers in the yellow/orange range.

Nicotiana (Nicotiana alata) is related to commercial tobacco, but don?t wrinkle your nose ? the fragrance is sensational. The tubular flowers are white and shades of rose and pink, with a surprising lime-green flowered variety. If fragrance is what you?re after, look for the old-fashioned varieties such as N. alata ?grandiflora.? Newer varieties are not as fragrant, but are more compact and have a longer blooming season.

Any article on bedding plants wouldn?t be complete without mentioning petunias (Petunia x hybrida). They offer a huge diversity of colors ? everything but green and orange. The grandiflora types can be striped or starry with amazingly intense colors. The edges of the flowers are usually wavy. The multifloras may have smaller flowers, but they tolerate heat a little better. Plus, the softer colors appeal to many people. Multifloras are the choice for container plantings.

Pinks (Dianthus spp.) are another bedding plant that offers a huge range of choices. The classic carnation is part of this family, but for summer color the China pinks are preferred. They flower in shades of pink, red and white, and have a frilly appearance and soft fragrance. The National Garden Bureau has declared 2004 as the year of dianthus.

Salvia (Salvia splendens) is a favorite of hummingbirds, with its spikes of scarlet flowers. Blooms can also be pink, violet, purple and white, but the red varieties are the most common. The tidy flowers withstand summer rainstorms with ease and thrive in areas where the nights are warm and humidity is high. (Plant in partial shade in the deep South and arid Southwest).

Snapdragons (Antirrhinum majus) are another garden classic that has been bred to offer a wide range of sizes and colors. Diminutive dwarf varieties barely reach eight inches tall, while the older varieties tower to three feet. The tubular, pouched flowers come in every color but blue, with some bi-colors. Did you ever pinch the throat of a flower to make it open and close?

If you?re looking for fragrance, be sure to include stock (Matthiola incana) in your garden design. Unlike nicotiana, new varieties offer the same sweet fragrance as the old-fashioned types, but come in a wider range of sizes. Keep in mind, though, that even the dwarf varieties reach to about 18 inches high. They look great planted in masses or mixed with other annuals in mixed borders.

Violas (Viola spp.) and pansies are both in the same family. Pansies are great for winter color in mild climates or as a fall planting in cold climes. Use them to fill in where summer annuals have given up the go to extend the flowering season. Violas do best in moderate temperatures and thrive in shady spots. Plant them as early as possible in the spring.

Zinnias (Zinnia elegans) are a garden favorite because of the wide range of colors, shapes and sizes, as well as their ease of culture. The flowers can be as large as seven inches across or as small as an inch-wide pompom ? in every color but blue. There are three main categories. The dwarf type make tidy mounds from about six to 12 inches high and wide. They are recommended for containers, mass plantings and edging. Tall varieties reach three feet, and can be used as a background for other blooming plants. They also produce a wonderful cut flower. Finally, Z. augustifolia, the ?classic? zinnia, gets about 10 inches tall, but sprawls to two feet wide. Flowers are golden orange, and its relaxed growing habit makes it great for rock gardens, accents and hanging baskets.

So, whether you are looking for a show-stopping display or a cheery accent, there is a bedding plant to suit your needs. Celebrate spring with colorful flowers!

Editor?s Note: Helen M. Stone is owner of Stone Peak Services, a horticultural communications and management firm based in Las Vegas, Nevada.

March 2004