About Petunia Flowers

Types

• Petunia cultivars generally fall under one of four types: grandiflora, milliflora, multiflora and groundcover (or spreading petunias). The largest petunia flowers are grandifloras, which can reach a diameter of 4 inches. Grandifloras grow best in dry climates and may be damaged by high levels of humidity. Multiflora flowers are not as large as grandifloras, but they bloom in larger numbers. The smallest version of petunias are milliflora, which are usually 1 inch in diameter. Groundcover petunias reach less than a foot off the ground, but can spread as much as 4 to 5 feet in a year. Some horticulturists also recognize a fifth group, the floribundas. These petunias are medium-sized, falling between the grandifloras and the multifloras.

Growth Requirements

• Petunias require at least five to six hours of sunlight per day to grow best. Longer periods of sunlight benefit petunias even more. If setting multiple petunia plants, give the petunias at least a foot of space between each plant. Grandiflora, multiflora and milliflora have a high degree of drought tolerance and only need to be thoroughly watered once per week. Groundcover petunias should be watered daily or every other day. Well-drained soil is preferable for growing petunias.

Landscape

• Gardeners plant all types of petunias for ornamental purposes because of the brilliant array of colors available. Use petunias to create a border for a flower garden and seasonal groundcover. Grandiflora and multifloras make the best border plants, while spreading petunias cover the ground effectively. Germinating petunias from seed is tricky, but experienced gardeners can extend the growing season by starting seeds indoors two to three months before planting the petunias in an outdoor bed. Move the plants outside after the threat of frost has passed and the soil has warmed above 60 degrees Fahrenheit.

Damage Control

• Petunias are susceptible to various plant diseases such as aster yellows, powdery mildew and root rot. Most diseases found on petunias are the result of overwatering, the primary causes of mildew or root rot. Some diseases come from bacteria caused by other plants. Faded leaf coloring and brown splotches are signs of disease. The best way to prevent diseases on petunias is proper watering and removal of infected leaves or flowers. Petunias are also susceptible to invertebrate pests, including caterpillars and mites. Pesticides are effective in dealing with mites, while handpicking is the best way to deal with caterpillars.