Oglala Lakota College

Agriculture & Natural Resource Department

Cooperative Extension Outreach

PO Box 490

Kyle, SD  57752




Fact sheet                                             Growing Petunias                                  Spring 2006

2006-g001                                           by Michel Melvin

Agricultural & Natural Resource Instructor


Petunias are one of the most popular flowering annuals and among the most popular bedding plants purchased each spring and summer.  They have a long flowering period, are easy to grow and are available in many forms and colors.


It’s no wonder petunias continue to rank among the most popular flowering annuals.  They’re bright and lively, bloom from spring until frost, and scent the air with lovely fragrance.  Best of all, they’re amazingly easy to grow, both in the garden and in containers.


This favorite annual flower was first discovered in South America more than two centuries ago.  The earliest petunias were small-flowered and lanky and were found in only two colors, white and purple.  But even as early as the beginning of the nineteenth century, European breeders were experimenting with crossbreeding to develop larger flowers and more colors.


Today, petunias are available in shades of white, yellow, pink, blue, purple, and red as well as bicolor, and as single or double flowers.  Many have a light, sweet fragrance, especially the blue petunia varieties.  Petunias make excellent cut flowers and will last for four to six days.


When you are buying bedding plants, look for plants with healthy foliage and plenty of buds.  There should be no signs of dried out or spotted leaves or powdery mildew.


For container planting, use a soil-less mix.  If you are planting petunias in the ground, choose a location with light, rich soil and good drainage.  (Petunias will grow in almost any kind of soil but do best in this soil.)  Work in some peat moss or compost before planting.  Mulch to help keep down weeds and retain soil moisture.


Petunias like full sun (at least six hours a day) but will do fine in partial shade.  However, in part shade the plants will flower less and the stems will stretch more.


These summer annuals are drought-tolerant, so don’t worry about watering unless there are prolonged periods of drought.  Window boxes and containers, especially those located under overhanging eaves, should be checked every few days, however, and watered as needed as the soil tends to dry out more.


By midsummer, your petunias may have stretch out stems and fewer flowers.  Prune them back severely to encourage new shoots and flowers to develop.  Don’t cut back trailing petunias.




Petunias can be transplanted into the garden after the danger of frost has passed.  In South Dakota, the last frost usually occurs around mid to later May.  Once the soil warms to about 60 degrees and danger of frost has passed start planting.


Plan to provide some protection from midday sun for the first few days, if weather is hot or windy with few clouds at transplanting time.  Plant petunias about 12 inches apart.  The spreading types should be planted 2 to 2 ½ feet apart.


Whenever feasible, it is a good ides to remove faded flowers, including the portion below each flower where seeds develop.  This practice, called “deadheading” encourages blooming by preventing seed maturation.  Although it may not be practical to deadhead masses of petunias in the garden, it’s a must for flowering annual containers.  Deadheading not only helps prolong blooming, it also keeps plants looking fresh, healthy and well-groomed.


Petunias have few serious insect or disease pests.  Aphids may be a problem.  Slugs feed on petunias and can be control led by the use of baits.  Avoid wetting the foliage and flowers to help prevent disease.


If you have an abundance of petunias blooming in the garden, it won’t hurt to cut a length of stem here and there to take indoors for use in bouquets and floral arrangements.  Just be sure to remove any leaves that will be submerged in the vase, where they would deteriorate rapidly.




Contact us at the Agriculture and Natural Resource Department of Oglala Lakota College

P.O. Box 490

Kyle, SD  57752


Leslie Henry, Dept. Chair


Theresa Lone Hill, Adm. Ast. 455-6085

Michel Melvin, Instructor












Julia Goings, Outreach Coordinator 455-6121

Randy Two Crow, Field Aid 455- 6121

Benny Rosales, Field Aid 455-6109