How to Grow Petunia
Annual
Petunias are among the most popular bedding plants in the United States, prized for their trumpet-shaped blooms in nearly every color and their long, dependable flowering season. Home gardeners grow them because they thrive in sun, adapt to beds, borders, and containers, and keep blooming from late spring until frost. They are treated as warm-season annuals across most of the country.
Planting
Petunias are almost always started from transplants set out after all danger of frost has passed and the soil has warmed, though seed can be started indoors about 10 to 12 weeks before the last frost date. Choose a site with full sun, meaning at least 6 hours of direct light per day, since shade reduces flowering and leads to leggy growth. Plant in well-drained soil enriched with organic matter, spacing plants roughly 8 to 12 inches apart depending on the type. Set transplants at the same depth they grew in their pots and water them in well to settle the roots.
Care
Keep the soil evenly moist but not waterlogged, watering deeply when the top inch begins to dry; containers dry out faster and may need water daily in hot weather. Petunias are moderate to heavy feeders, so work compost into the bed at planting and feed regularly through the growing season for the best bloom, especially in containers. Pinch back young plants once to encourage branching, and shear leggy stems by about a third at midsummer to renew flowering. Deadhead spent blooms on older garden types, and remove plants after the first hard frost since they will not survive winter in most regions.
Bloom time
Petunias bloom from late spring through the first fall frost, giving several months of nearly continuous color when kept watered, fed, and trimmed.
Garden uses
They excel in flower beds, borders, hanging baskets, window boxes, and mixed containers, where trailing and spreading types spill attractively over the edges. The flowers also draw pollinators such as bees and hummingbirds and add mass color to sunny plantings.
Tips
For the tidiest results, choose spreading or self-cleaning types that shed old blooms and need little deadheading, while older grandiflora types benefit from regular grooming. Avoid overhead watering late in the day so foliage dries before nightfall, and give plants good air circulation to reduce disease. If plants stretch and stop blooming by midsummer, a firm shearing plus consistent feeding and watering usually brings them back into full flower.
General guidance for US gardens. Timing and hardiness vary by region; check your local frost dates and hardiness zone. Page updated Aug 4, 2026.