To care for petunias, transplant after the danger of frost, water weekly and fertilize monthly. Remove any spent flowers to encourage more blooming. Spreading petunias and those planted in containers require more water.Continue Reading
Most gardeners transplant petunias rather than growing them from seed. Plants should have a minimum of three leaves before transplanting. Once the danger of frost passes, space the plants approximately 1 foot apart in loose, lightly drained soil. For a more abundant show of flowers, choose a location with full sun and protection from the wind. If necessary, the plants flower in partial shade, but expect fewer flowers. Choose a soil-less mix for growing petunias in containers.
Petunias are drought tolerant and require watering about once per week; however, flowers growing in containers and the spreading variety require more frequent watering than others. Water the plants thoroughly each time, and increase frequency for prolonged periods of drought.
Fertilize petunias once per month to encourage growth. For the double flowering varieties, increase the fertilizer frequency to every other week.
Leaving spent or wilted flowers on the vines causes them to slow their flower production. Pinch the flowers off the plant after they are spent.