Wave petunias, known for their rapid spreading habit, are a great choice for groundcover, containers and hanging baskets. Although they are usually seen for sale as seedlings, wave petunias can be grown from seed by starting them indoors in late winter, about 10 to 12 weeks before the last frost. Seeds are readily available from commercial growers and will produce plants true to type. Since the wave petunia is a hybrid, seeds gathered from existing plants may not produce seedlings true to the parent type.
Soak the peat pots in water for at least one hour, or soak peat pellets until they expand completely.
Drain excess water.
Fill peat pots, if using, with growing medium to within 1/2 inch of the tops.
Sprinkle seeds on top of the peat pots or peat pellets.
Press the seeds into the peat, using a wooden spoon. Push hard enough that the seeds stick to the peat, but are not covered by it.
Cover the peat pots with cling film.
Place the pots in a warm, sunny spot, but not in direct sunlight. Choose a spot with stable temperatures that do not fluctuate during the day.
Wait 10 to 12 days for the seeds to germinate.
Remove the cling film when seeds begin to sprout.
Water as needed, when the peat begins to dry out slightly, until the petunias are ready to transplant.
Look for pelleted wave petunia seeds. Pelleted seeds are coated to make them larger and easier to handle, which makes planting easier.
Don't bury the seeds under the peat. Petunia seeds need to be exposed directly to light in order to germinate; they will not grow if buried under the soil.