Petunias need to be planted in light, well-drained soil in full sun after the last spring frost. Petunias can grow in partial shade, but they will have fewer flowers. It’s better if the plants have shelter from the wind. Petunias are tolerant of heat so you don’t have to water them regularly. A thorough watering once a week should be sufficient (unless there are prolonged periods of drought in your area).
Fertilize your plants monthly to ensure good growth. Double-flowered cultivars like a biweekly dose of fertilizer. Remove faded/dead flowers to prolong blooming.