Petunias are an old favorite of many gardeners. They are easy to grow and maintain, come in a variety of colors and patterns. They do require deadheading (removal of spent blooms) to continue blooming throughout the growing season.
Petunias that we see today are based mostly on a couple of species discovered in South America back in the 1700s. Through extensive cross breeding, we now have an extensive selection petunias for any color palate a garden may want to use.
Petunias are classified into 4 broad categories:
Multiflora:the multiflora can be single or double blooms, which produces flowers all season long. Multifloras handle adverse weather conditions often found throughout many climates during a typical growing season.
Grandiflora: do best in cool temperatures. In high temperature areas the stems tend to stretch out. Grandiflora petunias have some of the largest blooms in the petunia family. They can be solid, bi-color, striped, or deeply veined. New cultivars of grandiflora petunia are more compact and disease resistant than many older varieties.
Spreading: these petunias are typicall low-growing (reaching only 4" - 6" in height and are often used as a spectacular annual ground cover. This category includes the trademarked Wave Petunia. Spreading petunias can withstand heat and humidity without problem.
Floribunda: available in both single and double flowered plants. Floribunda petunias are really just improved multiflora petunias. They flower earlier and are more extreme weather resistant.
Petunias love to be in full sun (6 or more hours in the north, slightly less than 6 in hotter southern climates), but will also tolerate partial shade. With reduced light levels, petunias will become leggy with fewer flowers.
Soil: petunias can adapt to most soil conditions, but grow best if the soil has good drainage. Add compost or peat moss before planting.
Fertilizer: a well-balanced garden fertilizer should be applied monthly during the growing season.
Water: petunias are quite drought-tolerant and usually don't require daily watering if planted in the ground. Container grown petunias should be kept evenly moist and avoid allowing the soil to dry out completely.
Deadheading: petunias produce more and better blooms if faded blooms are periodically removed by pinching off the spent bloom.
Pruning: petunias produce new blooms at the end of the stems and as the season progresses this results in leggy plants and fewer blooms. Cutting these stems back severely will produce new shoots and more flowers to finish the season in grand shape.