How to Plant and Grow Petunia

One of the most popular annuals, petunias add mountains of color to garden beds and containers. These tough plants are capable of producing loads of blooms all season long and come in a wide variety of colors and patterns. Most petunias available nowadays are hybrids. New varieties come out every year in novel shades and patterns. Countless color options are available, along with patterns like stripes, splashes, and even hearts. The blossom size selection is quite diverse as well. 

Whether you’re looking for a low-growing groundcover, a mounding type for containers, or a rambling wild plant to fill up some space, there is a petunia for every situation.

Where to Plant Petunias

Whether you plant petunias in garden beds or pots, they should get a minimum of 6 to 8 hours of direct sunlight per day. Pick a location where the soil is well-drained, with a pH in the neutral to slightly acidic range (6.0 to 7.0).

For the best visual effect, plant petunias in closely spaced groups or drifts. Trailing petunias look best when spilling over walls or containers and hanging baskets. Wherever you plant petunias in the landscape, make sure that they don’t get shaded too much by other plants, and keep in mind that they grow taller as the season progresses.

How and When to Plant Petunias 

Petunias can be planted when the soil has warmed to at least 60 degrees F and there is no more danger of spring frost. Loosen up the soil in the planting area and dig a hole at least twice the size of the root ball for each plant. Place it in the hole and backfill with a mixture of soil and compost. Gently tamp down the soil around the base and water the plants immediately. 

The spacing depends on the variety and location. Multiflora and grandiflora petunias should be spaced about 12 inches apart when planted in full sunlight and a couple of inches less when planted in partial shade. Trailing petunias should be spaced at least 18 inches apart. The compact milliflora petunias can be planted much denser, about 4 to 6 inches apart.

Petunia Care Tips

Light

It is important to plant petunias in full sun. Partial shade, especially in the hot afternoon hours, is acceptable in warm climates but too much shade can lead to fewer blooms and lanky plants. In shady locations, the soil also stays wet longer after a rainfall, increasing the likelihood of rot.

Soil and Water

Petunias are unfussy in terms of soil as long as they are planted in well-drained soils. Poor drainage, however, can lead to rot and fungal issues.

Petunias do not need lots of water, with two major exceptions: potted petunias and trailing petunias need frequent watering. In the absence of rain, in-ground petunias should be watered about once a week, more often during a heat wave. Container plants need daily watering. Petunias in hanging baskets might even need to be watered twice daily in hot summer weather.

Temperature and Humidity

Petunias are heat-loving plants. Hot weather is not a problem for them but they don’t handle high humidity well, so they are not the best choice for locations where summers are hot and humid.

Fertilizer

Because petunias are such vigorous bloomers, they need a substantial amount of nutrients to keep up their blooming power. Plant them in soils rich in organic matter and fertilize them regularly throughout the growing season with a balanced complete fertilizer.

Pruning

Petunias are fairly low maintenance, but many older varieties may require deadheading to keep up a constant display of blooms. Meanwhile, most new types are self-cleaning, so deadheading is unnecessary.

If they get too leggy, some petunias may also benefit from an occasional shearing back to help encourage a new flush of compact growth.

Potting and Repotting

Plant petunias in pots filled with well-draining potting mix and large drainage holes. Unglazed ceramic and terra-cotta pots are ideal because they let excess moisture evaporate. Potted petunias can be planted more densely than petunias in garden beds, depending on the variety, you can fit up to 3 plants in a 12-inch pot. They will need more regular watering than petunias growing in the ground. Repotting is usually not necessary as petunias conclude their life cycle with the first fall frosts.

Pests and Problems

Similar to flowering tobaccos, a close relative, petunias can attract some pesky bugs, especially during the heat of the summer, but rarely in large enough quantities to be of concern. Keep an eye out for whiteflies and aphids, as they are the most likely to show up.

Planting petunias in locations with poorly draining, wet soils, especially in partial shade, can make plants more susceptible to fungal diseases.

How to Propagate Petunias

Most petunias are hybrids that do not come true from seed. Some nurseries offer petunia seeds though the selection is much more limited than when buying plants.

Start the seeds indoors 8 to 10 weeks before the last frost in your area, in pots or seed trays filled with soilless potting mix. The seeds need light to germinate so do not cover them. Keep them evenly moist. At temperatures between 75 to 80 degrees F, the seeds should germinate in 7 to 14 days.

Harden off the seedlings before planting them outside after the last spring frost when the soil has warmed to at least 60 degrees F.

You can propagate petunias from cuttings taken from non-patented varieties, so if you break a stem from your plant, you can grow a new plant. Here’s how:

Remove a cutting about 6 inches long and strip all flowers and all leaves except the top pair. Place the cutting in a pot filled with moistened potting mix and firm it around the cutting. Place in bright, indirect light and keep the potting medium moist. After 2 to 3 weeks, your cutting should begin to show new growth.

Types of Petunia

Petunias have always been known for their vast selection of colors and patterns. The options seem almost endless. Here is a list of popular types:

‘Cascadias Bicolor Purple’ Petunia

Petunia ‘Cascadias Bicolor Purple’ is a heavy-blooming variety bearing purple flowers with a white star in the center. It has a trailing habit.

‘Cascadias Cherry Spark’ Petunia

Petunia ‘Cascadias Cherry Spark’ is a floriferous selection with pink flowers veined in dark purple. It has a trailing habit, making it good for hanging baskets.

‘Cascadias Sunray’ Petunia

Petunia ‘Cascadias Sunray’ is a trailing petunia with medium-size soft yellow flowers veined in rich yellow.

‘Double Wave Blue Velvet’ Petunia

Petunia ‘Double Wave Blue Velvet’ bears double, purple-blue flowers on vigorous plants that reach 6 inches tall and 2 feet wide.

‘Dreams Fuchsia’ Petunia

Petunia ‘Dreams Fuchsia’ is a large-flowering petunia bearing many bold fuchsia-pink flowers all summer. It grows 15 inches tall and 12 inches wide.

‘Easy Wave Blue’ Petunia

Petunia ‘Easy Wave Blue’ is a spreading petunia bearing tons of dark blue-purple flowers. It grows 12 inches tall and 40 inches wide.

‘Easy Wave Coral Reef’ Petunia

Petunia ‘Easy Wave Coral Reef’ is a spreading petunia with an abundance of dark coral-pink flowers. It grows 12 inches tall and 40 inches wide.

‘Easy Wave Mystic Pink’ Petunia

‘Easy Wave Mystic Pink’ Petunia is a spreading selection that bears creamy-soft pink flowers with a white center. It grows 12 inches tall and 40 inches wide.

‘Easy Wave Pink’ Petunia

‘Easy Wave Pink’ Petunia is a spreading hybrid with bright pink flowers all summer long. It grows 12 inches tall and 40 inches wide.

‘Famous Lilac Picotee’ Petunia

Petunia ‘Famous Lilac Picotee’ is a vigorous variety with a semi-trailing habit and lilac-purple flowers edged in white. It grows 1 foot tall and 2 feet wide.

‘Fantasy Pink Morn’ Petunia

Petunia ‘Fantasy Pink Morn’ bears soft-pink blooms with a white throat on compact plants that grow 1 foot tall and wide.

‘Madness Yellow’ Petunia

Petunia ‘Madness Yellow’ is a floriferous selection with clean yellow blooms, great branching, and season-long performance. It grows 15 inches tall and 18 inches wide.

‘Merlin Blue Morn’ Petunia

Petunia ‘Merlin Blue Morn’ offers rich purple flowers with a glowing white center. This award-winning variety grows 18 inches tall and wide.

‘Merlin Rose’ Petunia

Petunia ‘Merlin Rose’ produces beautiful pink blooms with a white and yellow throat on plants that grow 1 foot tall and wide.

‘Opera Supreme Pink Morn’ Petunia

Petunia ‘Opera Supreme Pink Morn’ bears bright pink flowers with a soft white center. This award-winning variety grows 6 inches tall and 3 feet wide.

‘Orchid Daddy’ Petunia

Petunia ‘Orchid Daddy’ is an award-winning selection with 4-inch-wide lavender-pink blooms that bear darker veins. It grows to 1 foot tall and wide.

‘Picnic White’ Petunia

Petunia ‘Picnic White’ is a mini petunia with an abundance of small white flowers. It grows 1 foot tall and 2 feet wide.

‘Pirouette Rose’ Petunia

Petunia ‘Pirouette Rose’ bears frilly, double, pink-and-white flowers on 1-foot plants. It’s not as heat-tolerant as many other petunia varieties.

‘Supertunia Bermuda Beach’ Petunia

‘Supertunia Bermuda Beach’ Petunia is an easy-growing selection that produces an exceptional number of salmon-coral blooms. It grows 10 inches tall and 2 feet wide.

‘Supertunia Bordeaux’ Petunia

‘Supertunia Bordeaux’ Petunia shows off soft pink flowers with rich purple-red veins. It’s a vigorous plant that bears a lot of flowers and grows 10 inches tall and 4 feet wide.

‘Supertunia Citrus’ Petunia

‘Supertunia Citrus’ Petunia is a vigorous selection with soft yellow flowers veined in rich yellow. It’s good for hanging baskets and can trail to 1 foot.

‘Supertunia Lavender Skies’ Petunia

‘Supertunia Lavender Skies’ Petunia is a vigorous variety that covers itself in lovely lavender-blue flowers that seem to change color throughout the day. It grows 10 inches tall and 4 feet wide.

‘Supertunia Mini Blue’ Petunia

‘Supertunia Mini Blue’ Petunia graces gardens with small, dark blue-purple blooms. It grows 8 inches tall and can spread to 6 feet.

‘Supertunia Pretty Much Picasso®’ Petunia

Rich purple flowers with deeper purple veins are edged in a bright chartreuse green.

‘Supertunia Raspberry Blast’ Petunia

A new color pattern in petunias, ‘Raspberry Blast’ has bright pink blossoms with a deep violet edging for an interesting new effect.

‘Supertunia Royal Velvet’ Petunia

‘Supertunia Royal Velvet’ Petunia displays an abundance of rich, blue-purple flowers all summer long. The vigorous selection grows 10 inches tall and 4 feet wide.

‘Sweet Sunshine Compact Lime’ Petunia

Petunia ‘Sweet Sunshine Compact Lime’ is a delightful double-flowering petunia with chartreuse-yellow flowers all summer long. It grows 14 inches tall and wide.

‘Sweet Sunshine Compact Nostalgia’ Petunia

Petunia ‘Sweet Sunshine Compact Nostalgia’ shows off beautiful, double soft-pink flowers touched with creamy yellow on a 14-inch-mounding plant.

‘Vista Silverberry’ Petunia

‘Vista Silverberry’ Petunia offers silvery pink flowers on vigorous, long-blooming plants that grow 2 feet tall and wide.

‘Wave Blue’ Petunia

‘Wave Blue’ Petunia liberally splashes bright purple-blue color through the garden, growing rapidly to 4 feet and blooming profusely all season.

‘Wave Misty Lilac’ Petunia

‘Wave Misty Lilac’ Petunia shows off silvery, soft-lilac flowers on a plant that grows 6 inches tall and 4 feet wide.

‘Wave Purple’ Petunia

‘Wave Purple’ Petunia is an award-winning selection with magenta flowers on 4-inch-tall plants that can spread 4 feet wide.

‘Wild’ Petunia

Petunia integrifolia is native to areas of Mexico and bears magenta flowers all summer long. It scrambles to 2 feet and often self seeds.

Petunia Companion Plants

Sweet Alyssum

Sweet alyssum, with its dainty, fragrant flowers, is frequently used in containers and hanging baskets to spill over the edges, creating a soft, frothy look. It’s also a great edging plant because of its tidy, compact habit. Regardless of how you use it, sweet alyssum does best in the cool conditions of spring and fall (or use it for winter color in very warm climates). In cool-summer conditions, such as in the northern third of the United States, sweet alyssum will bloom steadily through the summer. It halts bloom in summer in warmer areas.

Heliotrope

Even without its fabulous scent, heliotrope would be widely grown in the garden. The scent, somewhere between cherry pie, grape ice pop, and vanilla, makes it one of the most intriguingly scented plants in the garden. As a bonus, this tropical plant, grown as an annual, bears big clusters of rich purple, blue, or white flowers. Heliotrope thrives in a spot with full sun and moist, well-drained soil. It is also a great container plant. For the strongest scent, group several plants together where
they can get afternoon sun, which helps release the fragrance.

Salvia, Sage

There are few gardens that don’t have at least one salvia growing in them. Whether you have sun or shade, a dry garden or lots of rainfall, there’s an annual salvia that you’ll find indispensable. All attract hummingbirds, especially the red ones, and are great picks for hot, dry sites where you want tons of color all season. Most salvias don’t like cool weather, so plant them outdoors after all danger of frost has passed.