Emma DowneyByEmma Downey
Updated on 10/4/2022

Petunias: Where To Start, How To Grow Them, And How To Care For Them

Petunias are one of the most popular flowers due to the excellent blooms they produce and the extended amount of time that they are in bloom. Because, like most annuals, they get lanky by midsummer, you will need to clip the shoots so that they are approximately half as long as they were before. Find out how to plant your petunias and take care of them, so they continue to blossom.

About Petunias

Petunias are cultivated annually in most parts of the world; however, in Zones 9 through 11. They may be grown as sensitive perennials. The flowers bloom in various hues and designs from spring until the first frost of the season.

These vibrant annuals are typically used in borders, pots, hanging baskets, and even as a seasonal groundcover, and they can make a front lawn stand out with their splash of color. A few of them even have a very faint aroma. Their height may range from 6 inches to 18 inches, and their width can be anywhere from 18 inches to 4 feet along the ground. Their size can also fluctuate.

Various Forms Of Petunias

There are many distinct groupings of petunias, most of which are distinguished by the size of their flowers:

  • Petunias with many flower heads are the hardiest and most productive of the bunch. Because their blooms are less showy but more numerous, they are an excellent choice for summer bedding or use in a mixed border (because they are more tolerant to wet weather).
  • Petunia grandifloras produce exceptionally enormous blooms and do best when planted in pots or hanging baskets because of their compact growth (because they are more susceptible to rain damage). Because of how sensitive they are to rotting in the south's hot, humid summers, these huge petunias often do not fare as well in that region.
    • Floribundas are plants that fall between Grandiflora and multiflora in their flowering characteristics. They produce flowers of a size somewhere in the middle of those produced by the multiflora types, and they blossom freely.
  • Millifloras: Milliflora petunias are far more compact than any other kind of petunias now available. Although the blooms are just 1 to 1 1/2 inches across, there are a lot of them, and they endure the whole season.
  • Petunias that trail or spread out are low-growing flowers that may cover an area of up to three to four feet in width. Because the blooms bloom over the whole length of each stem, they provide a stunning groundcover that is rich in color. They are also suitable for use in hanging baskets or window boxes.



Petunias must have direct sunlight, or else they will have spindly stems. They tend to not blossom very well in shady areas.

In particular, the soil in containers has to have good drainage and should not be too damp. The soil should be relatively rich to promote the healthiest development. Before planting, amend soil that has low quality using finished compost.

When Should Petunias Be Planted?

  • The most convenient option is purchasing young plants from a nursery that offers petunias in flats. Look for plants that are small and dense in their growth. Petunias already loaded with blooms and tall and leggy won't establish themselves as quickly.
  • If you wish to produce petunias from seed, you should start the seeds indoors eight to ten weeks before your area's final spring frost. (Check the frost dates in your area.)
  • After the date of your area's last spring frost, it is safe to plant young petunias outside; nevertheless, you should keep a careful watch on the weather forecast and protect young plants from late frosts.

How To Get Petunias To Grow

  • Petunia seeds are very minute (they resemble dust!) and need a great deal of exposure to light to germinate.
  • Once the baby plants have developed three leaves, it is time to put them outdoors.
  • Leave a distance of roughly 1 foot between each plant.
  • When planting petunias in pots, use a potting mix specifically formulated for containers, which should allow excess water to drain away.



  • Because petunias can tolerate high temperatures for more extended periods, you won't need to worry as much about the need to water them often. A deep watering once a week should be adequate to keep the plant alive (unless there are prolonged periods of drought in your area). It's best to steer clear of watering plants too lightly since this might lead to weak roots.
  • It is important to note that petunias that spread and those grown in containers will need to be rinsed more often than those planted in the ground.
  • Petunias need to have a balanced fertilizer applied once a month to maintain their vigorous growth and prolific flowering. A dosage of fertilizer once every two weeks is ideal for double-flowered varieties.

What To Do With Petunias That Have Gone Leggy

  • By the middle of summer, most petunias tend to become leggy and produce flowers at the very end of long stalks that are now leafless. We cut down the branches of the petunias to approximately half their original length to keep them looking neat and encourage bloom production. This will stimulate the development of more branches as well as additional blooms.
  • After the plants have been pruned, they should be fertilized and well-watered to produce new growth and blossoms. In the beginning, the plants could have a ragged appearance, but with time, they will recover and produce more color and flowers.
  • Older garden petunia plants may be trimmed severely (to within a few inches of the base) to re-encourage vigor, particularly in colder areas; nevertheless, the remaining leaves should be allowed to stay on the plant.
  • Petunias with more giant flowers benefit the most from "deadheading," which is the process of removing spent, wilted, or dead blossoms. This improves the number of blooms and the plant's overall appeal. Removing spent blossoms and stems, also known as deadheading, prevents seed pods from competing with the flowers for the plant's resources. For recycling, clippings may be placed in a compost pile.


  • The 'Carpet Series' has garnered a lot of attention. They are great for use as ground cover due to their small size, early blossoming, flowers ranging from 1.5 to 2 inches in diameter, and vast range of color options.
  • The 'Primetime' series maintains its compactness and uniformity while being covered with blooms that measure 214 inches.
  • 'Heavenly Lavender' is an early, compact, double, deep lavender-blue variety with flowers measuring 3 inches and plants measuring between 12 and 14 inches.


  • 'Sugar Daddy,' which is part of the Petunia Daddy Series, has purplish blooms and black veins.
  • 'Rose Star,' a variety in the Petunia Ultra Series, has rose-pink blooms with a white center, giving the appearance that the petals are striped.


  • Petunias of the 'Celebrity' series are dwarf and may thrive in wet conditions. The diameter of the blossoms ranges between 212 and 3 inches.
  • Petunias from the 'Madness' series feature large blooms measuring three inches across and come in various solid and veined hues. They are tiny and bloom until the first frost, and they quickly recover after a rainstorm.
  • Petunias known as 'Double Madness' are dense and floriferous, producing large blooms measuring up to 3 inches across the growing season. The 'Double Madness' petunias, similar to their single-flowered cousins, recover after rainfall in hours.


  • The word "fantasy" conjures up images of tidy, condensed piles.

Trailing Petunias

  • In the category of spreading petunias, the cultivar is known as 'Purple Wave' was the pioneering variety. This plant produces large, deep rose-purple flowers. It can withstand high temperatures in the summer, as well as dry conditions and damage from rain. Purple Wave never reaches a height of more than 4 inches.
  • Petunias from the 'Wave' series are offered a broad spectrum of color options. Most of these versions are not nearly as low to the ground as the original. They can withstand adverse conditions, are immune to illness, and produce many flowers.


Petunias are not very susceptible to disease or harmful insects, although aphids and slugs may be a problem. When you water, don't get the leaves and flowers wet, which will help keep diseases at bay.

Petunia Insect Problems And Various Diseases


Type: Insect


Distorted and yellow leaves, twisted blooms, falling blossoms, sticky "honeydew" (excretion) on the leaves, and black mold on the plants.


Use a water spray to get rid of them, use insecticidal soap, carefully check young plants, use fertilizers with a delayed release, and stay away from excess nitrogen. Promote the presence of aphid-eating predators such as lacewings, lady beetles or bugs, and spiders.


Type: Mollusk


Holes in the leaves and flowers that aren't normal, a sticky secretion on the plants and the soil, and seedlings that “disappear.”


Handpicking; avoiding heavy bark mulch; using copper plant collars; avoiding overhead watering; laying boards on the soil in the evening; in the morning, lifting the boards, and disposing of the pests in hot, soapy water; are some of the methods that may be used. Suffocate in a deep container containing half an inch of beer or a mixture of sugar water and yeast that has been buried to ground level; put a strip of diatomaceous earth measuring one inch wide around plants.

Are you finally aware of how to grow petunias? Hopefully, this article has been able to help you in some way.