Petunias are annuals that bloom through summer and into autumn. Petunias grow well in all zones except the coldest and come in a variety of colors. You can use petunias for hanging baskets, in window boxes or as groundcover. In full sunlight, these annuals will bloom repeatedly with minimal care and add great splashes of color to any garden scene.
Buy compact, stocky plants from your local gardening center when you’re ready to plant. It’s possible to grow petunias from seed indoors, but the tiny seeds can be difficult to manage. The easiest way to get petunias quickly blooming in your garden is to purchase the young plants.
Wait until the danger of frost passes and the soil is warm before you plant petunias. Look for sunny spots in your garden or to place your pots, hanging baskets, or flower boxes. Petunias grow best in full sunlight.
Prepare your soil. Petunias like well-drained soil. Spread a layer of peat moss, or any kind of organic compost 2-3 inches thick. Till the earth to incorporate the new dirt into the old, breaking up the clay and hard-packed earth. This will help the soil hold in moisture, improve drainage and allow sunlight in.
Plant your petunias. Grandifloras and multifloras need to be spaced 12 inches apart in full sunlight. If they’re in a shadier space, you can put them a bit closer together. Millifloras need to be 4-6 inches apart, while the spreading varieties should be 1-1.5 feet apart. If you’re putting petunias in a container, plant them closer together to create a more pleasing display.
Water your petunias when they need it. Spreading petunias and container petunias will need a heavy daily watering. Other varieties need less; water your petunias every other day or as needed.
Deadhead you petunias when you can. Plucking off past flower blooms will increase blooming. Container petunias will need frequent deadheading; with spreading petunias, deadhead when and where you can.