More than a decade after the introduction of the Wave petunia, it’s one of the most popular varieties. Unlike standard petunias, Wave petunias are covered in 2-inch blooms and spread quickly. They are more disease-tolerant, stand up better to warmer and cooler temperatures and bounce back quicker from heavy rain. "Old-fashioned petunias were stringy and demanding, needing a lot of pinching and deadheading. Now you can just plant Wave, feed and water, and you have a wow display of color," said Stephanie Cohen, author of "The Perennial Gardener’s Design Primer."
Spread Wave petunia seeds or seed pellets sparingly on top of a container of clean, damp potting soil or milled sphagnum moss about 10 to 12 weeks before you can transplant to the early spring garden.
Water with a fine mist until thoroughly moistened or until the pellet dissolves off the tiny seed.
Cover the container with clear plastic and place it in a bright spot (but out of direct sunlight) that is warm, 70 to 85 degrees, until seeds begin to sprout, usually in seven to 10 days.
Remove the plastic cover once the seeds begin to sprout.
Place the container under a fluorescent light fixture in a cooler spot, about 65 degrees.
Turn on the fluorescent light for 16-18 hours a day, raising the light as the seedlings grow so that there is always 4 to 6 inches between the tops of the plants and the light.
Transplant into peat pots or packs when seedlings have three true leaves.
Add diluted liquid fertilizer every two weeks.
"Harden" the plants by putting them outside on sunny, warm days and bringing them back in at night for several days before planting them outside.
Set plants outside after about 10 to 12 weeks, once the danger of frost has passed, at the same plant depth as the pot or pack.
Choose a bright spot that gets at least six hours of direct sunlight.
Space the plants 12 to 24 inches apart in garden beds depending on how dense you want the planting to be.
Water every morning (on non-rainy days) so Wave petunias don’t dry out.
Add a liquid fertilizer every 10 to 14 days or a combination of liquid and slow-release fertilizer throughout the growing season if the plants are in the ground.
Add a liquid fertilizer more often, at least once a week, if your plants are in containers.