How to Grow the Most Popular Flowers

Roses, sunflowers, hydrangeas and daffodils are some of the most popular flowers in American gardens. Some have a high-maintenance reputation (roses, we're talking to you). Others sail along with little care.

Grow annuals, perennials, shrubs and ground covers with different bloom times, and you'll have a colorful show from spring into winter. Gardens are magical, but there's no wizardry required. Just visit the USDA Gardening Zone Map to find the right plants for your climate, and we'll tell you how to grow the most popular flowers.

Prima rosa is Latin for first rose, and primroses (Primula) are among the first spring flowers. Most cultivated types are hardy in Zones 5 to 9 and behave like short-lived perennials. In other zones, they're grown as annuals. Look for primroses in white, yellow, pink, red, purple, violet-blue and orange. Some grow to 24 inches tall but most mature at 8 to 12 inches.

Sow primrose seeds indoors in late winter or outdoors in a cold frame and transplant them when they have two sets of leaves. Most primroses like cool weather, partial shade, regular water and slightly acidic, well-draining soil mixed with organic matter. Plant young plants outdoors about two weeks before your last expected frost, spacing them every 6 to 12 inches. Protect them with frost cloth if there's a freeze.

Cheerful pansies (Viola x wittrockiana) bloom in early spring. These short-lived perennials get leggy and produce fewer flowers in warm weather, so most gardeners treat them as annuals. In mild-winter areas like Zones 7 to 10, pansies flower through the winter, wilting but perking back up after a frost. They also provide cool-weather color in Zones 4 to 6, although they may go dormant when temperatures drop very low.

Give pansies six hours of daily sun and organically rich soil. Mix in slow-release fertilizer at planting in the amount indicated on the fertilizer label. Southerners can sow pansy seeds outdoors in the fall and all gardeners can start seeds indoors for blooms in 10 to 12 weeks. Pansies grow best with night temperatures in the 40s and days in the 60s. Water them regularly while they're actively growing and let the soil dry out slightly between waterings.

All types of cosmos, including Cosmos bipinnatus, C. sulphureus and C. atrosanguineus, are grown as annuals in the US and bloom from late spring or early summer until frost. After your last frost, scatter the seeds over loose, well-draining soil or sow them in shallow trenches in full sun. Cover them lightly. If you prefer, start the seeds indoors four weeks before your last frost; put the seed trays on a heating mat and cover them to retain humidity. Gently water the soil and keep it moist until the seeds germinate. For a steady supply of flowers, sow more seeds every 4 weeks.

After all danger of frost has passed, transplant cosmos into your garden 9 to 12 inches apart. They need well-draining soil with moderately low fertility and a neutral pH. Don't fertilize. When the seedlings are 6 inches tall, pinch them just above the first or second leaf node to encourage branching. Deadhead faded flowers or let them set seeds to drop and self-sow.