Petunias are popular, sun-loving flowering annuals. Provided they receive enough light, water and general tending, these flowers will cheer your garden for several months during the spring and summer. Gardeners new to growing petunias may, however, inadvertently skip some steps necessary to keep the flowers blooming. A few simple steps help keep these flowers blooming longer throughout the warm months.
Water petunias at soil level only. Never spray the blossoms. Petunia flower petals are delicate. Extension.oregonstate.edu suggests using a soaker hose to water petunias. These flowers will close up for days after being rained upon--whether the water on the petals comes from the sky or your sprinkler.
Pinch off spent petunia blossoms--this is known as deadheading. According to the University of Minnesota Extension, you should remove the entire dead bloom, including the green area near the stem where seeds will form. In other words, do not simply pull the colored petals off--pull the entire flower head off.
Fertilize your petunias with appropriate fertilizer at the right times. If your petunias are planted in your garden, University of Minnesota Extension suggests using a balanced fertilizer (look for those labeled with the same number across the board--8-8-8, for example) in the soil before planting. After that, fertilize weekly or every three weeks with a liquid fertilizer. For potted petunias, fertilize every two weeks with flower fertilizer, unless the potting soil contains a time-released fertilizer.
Check petunias frequently for harmful insects such as aphids, advises extension.oregonstate.edu. The insects may sap life from the plants or spread diseases. Control insect pests with organic or chemical sprays, if necessary.