Wave petunias are an improved cultivar of petunia that is easier to grow, hardier and more disease resistant than traditional petunia varieties. Wave petunias are low-growing, spreading petunias that look good as a ground cover or tumbling out of the sides of a hanging basket or planter. Although Wave petunias are trademarked and should not be propagated from cuttings at home, you can purchase seeds to start Wave petunias at home for instant color as soon as all danger of frost has passed. Petunia plants are very difficult to grow from seed, according to the University of Minnesota.
Select Wave petunia seeds in packets at a garden center or nursery. Popular varieties of Wave petunias that you can purchase from seed include Shockwave, Double Wave and Tidal Wave.
Fill a seedling tray with peat moss. Sow the seeds sparingly directly into the top of the peat moss. Wave petunia seeds are as fine as dust, and need light to germinate.
Water with a fine mist to wash the seeds into the soil and to get the soil as damp as a wrung-out sponge.
Cover the seedling tray with plastic and place it on a seedling warming mat well away from light. Wave petunias should not be placed in sunlight until they sprout. The seeds will germinate best at temperatures between 78 and 80 degrees. The seedlings should germinate in seven to 10 days.
Remove the plastic once the seeds germinate and place the seedling tray 6 inches below a bright fluorescent lamp. The seedlings will grow best in temperatures from 55 to 65 degrees. Raise the lights as the seedlings grow so that they always remain 6 inches from the tops of the plants.
Attach the lamp to a timer and adjust the timer so that the petunias receive light for 16 hours daily.
Transplant the seedlings into 4-inch-wide containers filled with peat moss when they sprout three true leaves. To do so, fill the containers with peat moss. Hollow out a planting pocket in the planting mix and place the root ball of the petunias in the planting pocket. Cover with peat moss and water until the peat moss is as damp as a wrung-out sponge. Place the pots beneath the fluorescent lights.
Move the containers of Wave petunias outdoors into the shade during daylight hours for three consecutive days to harden them off once all danger of frost has passed and the soil has warmed to about 60 degrees.
Transplant wave petunias into containers or into the ground once the soil reaches 60 degrees and the plants are hardened off. To do this, open a planting pocket into the soil that is twice as wide as the root ball, but no deeper. Place the root ball in the planting pocket and fill in around the sides with soil. Water until the ground is as wet as a wrung-out sponge.