Petunia: Ultimate Growth and Care Guide

Looking to add vibrant, long-lasting color to your garden? Petunias, with their large trumpet-shaped blooms and a variety of striking colors, are a gardener’s favorite. From hanging baskets to garden beds, these versatile flowers bring charm and vibrancy to any outdoor space.

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Introduction to Petunias

Petunias are part of the Solanaceae family and native to South America. They are cherished worldwide for their vibrant colors, diverse patterns, and versatile growth habits. Available in hues ranging from soft pastels to bold reds, purples, yellows, and even black, petunias come in both single and double blooms with ruffled or smooth textures. Some varieties, like the Wave and Supertunia series, offer exceptional spreading or trailing habits, making them perfect for hanging baskets, window boxes, and garden borders. 

Petunias bloom profusely from Spring until the first frost, providing season-long color when properly cared for. They thrive in full sun, needing at least 6-8 hours of direct light, well-draining soil, and regular feeding to maximize their flowering potential. Petunias not only bring beauty but also support pollinator activity, attracting bees, butterflies, and hummingbirds with their nectar-rich blooms. Though relatively low-maintenance, regular deadheading helps encourage continued blooms, though some newer cultivars like Supertunia self-clean.

In my younger years, I abhorred the high maintenance Petunias of my generation. But, in the last decade and the evolution of the self-cleaning Petunia, I now use Petunias in every zone of my gardens. When it comes to modern petunias, the saying “these aren’t your Grandma’s petunias” fits perfectly.

Characteristics of Petunias

Petunias are known for their vibrant hues, ranging from solid colors like red, white, and purple to striking patterns like speckles, stripes, and starbursts. With proper care, Petunias bloom non-stop from spring to fall and can withstand light frosts and still maintain their vigor. Their trumpet-shaped flowers are perfect for filling out garden beds or cascading from containers.

Size and Growth Habit

Petunias offer a wide range of growth habits, from compact mounding types like Potunias to vigorous, sprawling varieties such as Wave Petunias, which excel as colorful ground covers. Among the most celebrated are Supertunias, a trademark series from Proven Winners, known for their exceptional branching and prolific blooming, making them a favorite among gardeners seeking reliable, showy displays. Compact typically grow between 6 to 12 inches tall and wide, while more vigorous spreading and trailing types can reach up to 4 feet, making them perfect for creating lush, cascading displays. 

Leaves and Flowers

Petunia foliage ranges from light to medium green, with a slightly fuzzy or sticky texture that releases a mild, earthy scent when brushed or handled. The small to medium-sized leaves provide a subtle yet attractive backdrop, allowing the vibrant, eye-catching blooms to remain the focal point.

The trumpet-shaped flowers of petunias vary from 1 to 3 inches in diameter and are available in a dazzling spectrum of colors, including solid hues, bicolors, stripes, and speckled patterns. Petunias come in both single and double-bloom forms, with some varieties showcasing ruffled, scalloped, or fringed edges for added texture and visual appeal.

Are Petunias Annual or Perennial?

Petunias are typically grown as annuals in most regions due to their sensitivity to hard freezes (below 26°F). However, in USDA Hardiness Zones 9–11, they can behave as tender perennials and continue blooming year-round if protected from cold temperatures. In Zone 8, Petunias are treated as annuals but can have an extended growing season if a hard frost is delayed or if they are grown in sheltered conditions. In Zone 8b, Petunias may survive as evergreen all winter. In Zone 8a, depending on the freezing temperatures, some of the more hardy Petunias can survive as root-hardy perennials. For gardeners in cooler climates, Petunias can also be overwintered indoors in bright, frost-free environments, allowing them to be replanted the following spring.

Best Varieties of Petunias Tested

Best Variety #1: Supertunia Vista Bubblegum & the Supertunia Series Petunias

Hands down the most popular varieties of Petunias are the Supertunias, a trademarked variety of Petunias owned by Proven Winners. And, of the Supertunias, the most popular by far is Vista Bubblegum, a bubblegum pink variety. Superior branching, early to bloom, super hardy and a self-cleaning ~2” bloom make Supertunias the #1 Petunia in America.

Best Variety #2: Wave Petunia

The original purple wave Petunia debuted in 1995. Since then the universe of Wave Petunias has expanded significantly. Known for its vigorous growth and spreading habit, Wave Petunias are ideal for ground cover or in large hanging baskets. There are 5 different varieties of Wave Petunias … the original Wave, Double Wave, Easy Wave, Shock Wave, and Tidal Wave, each having different characteristics. There are 6 that have received All America Selections (AAS) designations. In sum, these super fast growing Petunias can cover some ground or rock a container or hanging basket. They span in size from 2 feet to more than 5 feet in diameter (Tidal Wave Series). They are self-cleaning and very popular with gardeners. Ranking wise, many came along 10-20 years ago before trial gardens were in place and consequently there are few rankings to relate but needless to say they have survived this long as gardener favorites for a reason.

Best Variety #3: Crazytunia Black Mamba Petunia

Black Petunias have grown in popularity over the past 5 years and it is now a staple at many garden centers. Although there are several black Petunias, the only black Petunia to receive a 5.0 rating in test trials is the Crazytunia Black Mamba Petunia, which makes it the best variety, end of discussion.  

Best Variety #4: Bee’s Knees AAS Petunia

In recent years, Ball Horticulture has made huge advances in Petunia genetics resulting in a recent All America Selection (AAS) designation for the bright yellow Bee’s Knees Petunia. It also won a gold medal from AAS, which has not been awarded to a Petunia variety in 50 years. Bee’s Knees is both vibrant and resilient, adding a sunny yellow touch to any space.

Best Variety #5: Aquamarine Mini-Vista Petunia & Mini-Vista Series

You can’t argue with independent trials … the Proven Winner Mini-Vista Petunias has extremely high rankings and their mini-Petunias measuring about 1” in diameter tend to be more compact with less spread. The size of the blooms is comparable to Calibrachoa, but with the hardiness of Petunias.

Honorable Mention #1: Crazytunia Moonstruck & Crazytunia Series

Crazytunia, a Petunia brand from breeder Westhoff, is crazy good. Fifty-five (55) unique Petunia color combinations, and about half with great trial ratings in the 4.8-5.0 range. Can’t go wrong with Crazytunia.

Honorable Mention #2: Headliner Night Sky & the Headliner Series

The Headliner series of Petunia, by breeder Selecta North America, are mesmerizing, particularly the Sky series with its white speckles and high trial ratings (most from 4.8-5.0).  are premium. Making headlines everywhere.

Honorable Mention #3:  Surfinia Heavenly Blackberries & Cream and the Surfinia Series of Petunia

Surfinia, a fun and highly rated series by breeder Suntory Flowers, provides some rich color combinations not always found in other series of Petunia. 

How to Grow & Care for Petunia

Petunias are a garden favorite known for their vibrant, trumpet-shaped blooms that add a pop of color to flower beds, containers, and hanging baskets. Their low-maintenance nature and wide range of colors make them a versatile choice for gardeners of all skill levels.

Planting Petunias

Plant Petunias after the last frost; while they are frost-resistant, Petunias thrive best in warmer conditions. Use well-draining soil enriched with organic matter to provide essential nutrients, and space plants according to their growth habits to promote airflow, reduce disease risk, and encourage healthy growth. For hanging baskets, place 2-3 plants in a 10-inch basket, adding one plant for every additional 2 inches in size. In containers or troughs, space plants 6-8 inches apart to allow for natural spreading.

Sunlight Requirements

Petunias require 6 to 8 hours of direct sunlight daily for peak blooming. While they can tolerate partial shade, excessive shade will reduce flower production. In areas with extreme heat, afternoon shade can prevent plant stress and wilting. Adequate sun exposure ensures vibrant colors and steady blooms throughout the season.

Soil Requirements

Petunias prefer light, well-draining soil rich in organic material. The ideal pH range is slightly acidic, from 5.5 to 6.5. Soil that is too alkaline can hinder nutrient uptake, resulting in poor plant health. For heavy clay soils, incorporate compost or soil conditioner to improve drainage. For container growth, a high-quality, lightweight potting mix with good drainage is essential to prevent waterlogged roots and promote healthy growth.

Watering Needs

Petunias are more drought-tolerant than Calibrachoa but still perform best with consistent moisture. Water deeply, allowing the top layer of soil to dry slightly between waterings to avoid overwatering. Hanging baskets and containers dry out faster than garden beds, often requiring daily watering, especially in hot weather. During extreme heat (90°F or higher), check soil moisture twice daily to prevent dehydration. Though petunias can look wilted and stressed when dry, they recover remarkably well with a thorough soaking, often bouncing back without significant yellowing or bloom loss. This ability to recover from drought stress is why experienced gardeners prefer Petunias over Calibrachoa.

Fertilizer Needs

Petunias are heavy feeders that benefit from a consistent supply of nutrients. Apply a 6-month slow-release fertilizer at the time of planting for long-term feeding. To support steady blooming, supplement with a water-soluble fertilizer every 1 to 2 weeks throughout the growing season. Choose a fertilizer with a balanced or phosphorus-rich formula to encourage continuous flowering. Be cautious with nitrogen-heavy fertilizers, as they promote leaf growth at the expense of blooms. Periodic calcium additions, whether through eggshells or organic and inorganic fertilizers, are also helpful in maintaining bloom vigor. With Petunia, watch for yellowing of green foliage as this most often suggests the need for Epson salts (MgSO4) as a lack of Magnesium prevents nutrient uptake.  

Pruning & Deadheading

All of the new Petunia hybrids are self-cleaning which means spent blooms drop off naturally, eliminating the need for deadheading. However, to maintain a tidy appearance and promote fresh growth, trim back leggy stems or pinch back one stem per week. This method encourages bushier growth and increased flower production. For plants that begin to look sparse in midsummer, a more significant trim will revitalize the plant’s shape and vigor.

Common Pests

In comparison to its cousin the Calibrachoa, Petunias are less likely to be attractive to pests such as aphids, spider mites, and thrips. However, regular investigations should be performed, especially around 2 months after the last frost, as budworms become prolific. Budworms feed on tender flowers, such as Petunias, often causing plants to stop blooming. Use Bacillus thuringiensis (BT), a biological control that targets caterpillar larvae. Ensure flowers are completely covered and within a week, your plant will begin budding and blooming again.

Common Diseases

Petunias are not generally susceptible to fungal diseases. Maintaining good airflow, avoiding evening watering, and ensuring soil drains properly will deter fungal diseases.

Common Mistakes

When it comes to growing Petunias, even experienced gardeners can encounter challenges. Here are the three most common mistakes to avoid:

1. Allowing Petunias to Overgrow
   Petunias are fast growing, hardy plants and they will rapidly overtake and bully other plants in a combined container. To maintain a lush, full appearance, aggressively cut back Petunia plants until other container plants can catch up. After less vibrant plants are caught up, pinch back one branch or stem from Petunias weekly and aggressively cut back Petunias when necessary. This encourages denser foliage and promotes continuous blooms.
2. Allowing Plants to Dry Out
   Because Petunias are aggressive growers and will fill containers quickly, containers are especially vulnerable to drying out, particularly in temperatures exceeding 90°F. If the soil dries out completely, Petunias revive quickly but big plants in a small pot make Petunias unhappy. Repeated cycles of drying and "crashing" can permanently damage the plant, making it unsightly.
3. Failing to Fertilize Adequately
   Even nutrient-rich soil can only sustain plant growth for a limited time - typically 90 days. Petunia are heavy feeders. Without additional feeding, plants may exhibit poor growth and reduced blooms. Apply a slow-release fertilizer at planting time and supplement with fertilizer heavy in phosphorus every 1-2 weeks to keep plants performing at their best. Don’t forget the need to add Epsom salts if yellowing occurs.

Common Misconceptions

Several misconceptions about Petunias still persist among gardeners. Clarifying these misunderstandings can lead to better plant performance and overall success.

1. These AIN’T Your Grandma’s Petunias
   95% of all Petunias sold today are self-cleaning. In sum, the Petunia’s your Grandma kept that required deadheading to keep them looking good are extinct. Gone. Ended. No Longer. The new hybrids are self-cleaning which means that the spent blooms naturally fall away, keeping the plant looking fresh. Only the inexpensive Petunia varieties comprising bedding flats require self cleaning. 
2. Petunias Are Bullies
   Petunias are fast growing, hardy plants that will bully any other plant placed in a shared container. Don’t be fooled… cut back your Petunias aggressively where necessary so that you don’t have to forsake your companion plants
3. Heat Causes Petunia to Stop Blooming
   When Petunias stop blooming during the peak of summer, many gardeners assume the heat is to blame. However, the true culprit is often the budworm—a pest that feeds on tender flower buds, interrupting the bloom cycle. To resolve this issue, apply Bacillus thuringiensis (Bt) to the affected plants. Blooms typically resume within a week of treatment.

Using Petunias in the Garden

Petunias are a versatile addition to any garden, offering vibrant color and a variety of growth habits to suit different spaces. Spreading varieties including waves and Supertunias can make an impact as borders in the garden. Trailing varieties excel in hanging baskets and containers, where their cascading blooms create eye-catching displays. Compact Petunias or Potunias are perfect for fillers in garden containers and for providing a tidy, colorful border throughout the season. 

Hanging Baskets

Petunias are ideal for hanging baskets, thanks to their trailing and cascading growth habits that create a striking waterfall of vibrant blooms. When combined with complementary trailing plants, hanging baskets filled with Petunias add dynamic beauty to patios, porches, and balconies. Regular pinching for legginess and to prevent Petunias from overtaking slower growing plants, as well as fertilizing will ensure continuous blooms and a lush, overflowing look.

Garden Beds & Borders

Fast spreading Petunias such as Wave & Vista Supertunia varieties are perfect to form mats of color in garden beds. Place these with other fast growing prostrate plants such as sweet potato vine for striking color contrasts. Center spreading petunias around a contrasting colored Thriller (grasses or coleus) for unique and expansive garden coverage.

Compact upright Petunia such as Potunia varieties make excellent edging plants for garden beds and pathways. Their uniform height and prolific blooms create a colorful, tidy border that defines garden spaces beautifully. They can be paired with taller background plants, such as ornamental grasses or perennials, for added depth and contrast. With proper spacing and care, Petunias maintain their neat appearance throughout the growing season.

Pollinator Gardens

Petunias are a magnet for pollinators like bees, butterflies, and hummingbirds, making them a valuable addition to wildlife-friendly gardens. Their brightly colored, trumpet-shaped flowers are easy for pollinators to access, providing both nectar and visual appeal. Planting Petunias alongside other pollinator-friendly species, such as lavender, salvia, or milkweed, enhances biodiversity and supports local ecosystems. Choosing single-flower varieties over doubles will further encourage pollinators, as they are easier to navigate.

These AIN’T Your Grandma’s Petunias

Ready to bring their cheerful blooms to your garden? Purchase Petunias online today and enjoy a season full of stunning color and beauty!