Volunteer Petunia

In Texas often the winters are so mild that petunias volunteer the next year. This means a hardy root structure exists and the petunias will return large and strong. These petunias are in their third and fifth year of volunteering. This means they made it through the winter of 2010, which was a much harder winter than 2011.

This is why petunias are a good choice, other than the fact that once the nights reach 85 to 90 degrees, the petunias and geraniums stop blooming. So … that’s not good. However, these are lovely, lovely until the July 4 and they will resume blooming in October.  Deep purple looks wonderful in the late fall and works well with the Encore azaleas.   The Encores rally in the fall with a light crop of blooms.  Nothing spectacular and hardly worth the effort but there you have it.  Nurseries love to sell them!  I would rather see mums in the fall than a weak repeat of azaleas.

A volunteer petunia is a petunia plant that grows on its own, without being intentionally planted. These typically come from seeds dropped by petunias from a previous growing season. The seeds overwinter in the soil and germinate when conditions are right—usually in spring.

Which Petunias Are Most Likely to Volunteer?

1. Heirloom or open-pollinated petunias – These are most likely to come back true to type and reseed easily.

2. Old-fashioned Grandiflora and Multiflora types – These can drop viable seeds, especially in garden beds.

3. Wave® petunias and hybrids – Less likely to volunteer because they are hybrids and often sterile or don’t come true from seed.

4. Petunia integrifolia – A wild species that reseeds freely in warm climates like much of Texas.

5. Supertunias (by Proven Winners) – Rarely volunteer; bred to be sterile or less seed-producing.

Texas Considerations:

• East Texas: Mild winters can allow seeds to overwinter more successfully in mulch or loose soil.

• Central Texas: Hot summers and occasional hard freezes reduce volunteer success. Volunteers may germinate after mild winters but will need watering during drought.

Q1: What conditions encourage petunias to volunteer in Texas gardens?
A: Warm, mild winters and moist, well-drained soil increase the chance of self-seeding. Petunias that were allowed to go to seed in the fall, especially in mulched or protected beds, are more likely to reappear in early spring.

Q2: Are volunteer petunias likely to resemble the original plant?
A: If the original petunias were open-pollinated varieties, the seedlings often look similar. However, if they came from hybrids (like Supertunias or Wave petunias), volunteers may have unpredictable or less vigorous traits due to genetic variation.

Q3: How can I encourage volunteer petunias without replanting?
A: Allow some of your petunias to go to seed in late summer. Avoid heavy mulching or digging in the fall, and water lightly in early spring to support germination. Avoid using pre-emergent herbicides in areas where you want volunteers.

Q4: Do volunteer petunias bloom as well as planted ones?
A: Sometimes. Volunteer petunias may bloom later and be less uniform, especially if they come from hybrids. However, in fertile, moist soil, they can perform well, particularly in East Texas.

Q5: Are volunteer petunias reliable in Central Texas?
A: Less so. Central Texas winters can be too cold for seeds to overwinter reliably, and early spring droughts can limit germination. You may see some volunteers in mild winters, but irrigation and shading are often needed to help them thrive.