When to Plant Wave Petunias

Spring or Summer

• Plant wave petunias in full sun after your area is no longer threatened by frost. This date will vary from area to area, but generally occurs between March and July. Petunias will suffer cold damage if subjected to frost, so don't be tempted on a warm spring afternoon to plant your petunias and other cold-sensitive plants just because they're available in your local nursery. Check the average local last frost dates for your area to determine when to plant your petunias.

Heat Tolerance

• If possible, plant your wave petunias outdoors at least several weeks before the summer heat hits. Some varieties, such as "Tidal Wave Silver," are extremely heat-tolerant, even for summers that are regularly above 90 to 100 degrees Fahrenheit, and may fare better than others if planted shortly before the first heat wave.

Planting Seeds

• Plant wave petunia seeds indoors about 10 to 12 weeks before the last expected frost. Depending on where you live, this could be anytime from January to May. Transplant them to larger containers before taking them outside after the last frost.

Hardening Off

• If your wave petunias are used to your home or greenhouse, they will experience shock when you plant them outdoors unless you get them accustomed to it first. Simply take your petunias outdoors to a shady area for about two to three hours and then bring them back in. The next day, keep them outdoors for two or three hours longer, but half the time spent in the sun. Each day for about 5 to 7 days, lengthen the amount of time they spend outdoors in the shade and sun so they slowly acclimate to their new climate.