Annual petunias add color to flower beds and containers. Petunias are available in a variety of colors and include double- and single-petal varieties. As a warm-weather flowers, petunias do not tolerate freezing, so protection is necessary during late-spring or early-fall freezes if you wish to prolong their lives. They also need to be protected from hot, drying winds in the summer, as these can lead to dry soil or premature petal drop. Protect and care for your petunias to ensure they bloom all season long.
Transplant petunias outside in spring after frost danger is past and once the soil temperature reaches at least 60 degrees F. Plant on a cloudy afternoon to protect the petunias from sun scald while they adjust to their new bed.
Apply a 2-inch layer of organic mulch, such as bark or straw, around the plants to preserve moisture in the summer heat and to guard the roots against an unexpected freeze.
Cover the plants with burlap sacks or place an upturned box on top of the petunias at night if a light freeze is predicted in late spring or early fall. Remove the sack or box once the frost danger has passed.
Bring potted petunias inside if a frost is expected. Place them in a sunny window and move them back outdoors once frost danger is past.
Check for aphids on the plants at least once weekly to protect the petunias from the spread of viruses. Look on the underside of leaves for spotting or small colonies of insects. Dislodge the aphids with a spray of water or treat the plants with insecticidal soap.
Water the petunias when the soil begins to feel dry, especially in summer when they are more prone to heat stress. Water once a week with about 2 inches of water or twice a week during hot, dry periods.