How to Plant, Grow, & Care for Petunia Flowers

Are petunias perennials or annuals?

Although they are actually classified as tender perennials, they won't tolerate frost so they are commonly grown as annuals in most climates.

Sun or shade?

Full sun

Bloom time:

Summer

Color and characteristics:

You can find them in just about any color, even black, as well as striped, veined, and speckled patterns. The variety of flower forms is also impressive, ranging from petite to palm-sized in single or double blooms with ruffled, fringed, or smooth edges.

When to plant:

In spring, after the threat of frost has passed.

Where to plant:

For the best performance, plant in full sun (at least six hours a day). They will tolerate some shade, but may not flower as prolifically.

Soil:

They grow best in a light, fertile soil that provides good drainage and is slightly acidic (pH 6 to 6.5). In heavy clay soils, work some compost, or other organic matter into the ground before planting. When planting in containers, use a free-draining soilless potting mix fortified with a slow-release fertilizer.

Grow petunias from seed:

You can also grow many types from seed if you’re after a certain variety not available as a transplant. Because petunia seeds are very tiny and slow to germinate, you’ll have better success starting the seeds indoors 8 to 10 weeks before the last frost date in your area and transplanting the seedlings into the garden once the soil warms up.

Water:

Petunias need regular watering because their shallow root systems dry out quickly. However, make sure the soil is well drained because soggy soil can cause root rot and yellowed foliage. Petunias grown in containers may need more frequent watering, possibly every day, especially in hot weather.

Fertilizing:

To keep petunias blooming vigorously throughout the summer, apply a monthly dose of liquid fertilizer or a slow-release granular fertilizer at the time of planting. Plants in containers often need more frequent fertilizing because the nutrients get washed out.

Pruning and deadheading:

The amount of pruning required often depends on the variety you’re growing.

• Traditional grandifloras require the most work and need frequent deadheading to prevent plants from going to seed.
• Self-cleaning and spreading varieties do fine without pinching or pruning. Occasional deadheading will boost flower production and create fuller plants.
• If your plants begin to get leggy and have fewer blooms, cutting them back will encourage new growth and more branching.

Pests and diseases:

Petunias can be bothered by pests like aphids, thrips, mites, caterpillars and budworms; as well as powdery mildew.

Get more advice on keeping your petunias blooming all summer long:

Caring for Supertunias® (from Proven Winners)

Nearly all petunia plants sold today are hybrids. Some new petunia varieties and hybrids have become so popular, they have created a class of their own, such as the Supertunia®.

Supertunias®:From Proven Winners®, vigorous bloomers that produce flowers in a broad range of colors.

• Supertunia® Vista: Landscape plants with medium-sized flowers, growing up to 2 feet tall and 3 to 5 feet wide.
• Supertunia® Charm: Densely-branched container plants with small flowers.
• Supertunia® Trailing: Strongly trailing plants with medium flowers.
• Supertunia® Double: Plants bloom with fully doubled flowers.

Spreading, or Wave® petunias: Introduced by Ball Seed Co., energetic growers with trailing stems that spread up to 4 feet or more.
Grandiflora petunias: One of the oldest types, producing large flowers, although fewer; mounding to 15 inches.
Multiflora petunias: Blooms with smaller flowers and has a more compact growth habit.
Floribunda petunias: Hybrids of grandiflora and multiflora, producing grandiflora-like blooms with the vigor of a multiflora.
Milliflora petunias: Only about 8 inches tall and wide and produce tiny 1-inch blooms.

Petunias are very popular flowers for adding instant color to a garden. They are incredibly versatile and can be used in many ways. Here are some ideas:

• Plant them as colorful additions to seasonal landscape beds
• Grow them individually in hanging baskets and window boxes or along with other strong growers
• Use them in containers as the filler or spiller component
• Plant petunias in masses for a dramatic blanket of color
• Cover bare spots in your garden quickly and prevent weeds