Though easy-to-manage petunias bring interest to your gardening space through their ruffled to fringed textures, sweet fragrance and colorful palette, these seemingly ideal annuals may appear smaller than expected due to a variety of problems. Diseases induced by pathogens or improper growing conditions may result in dwarfed flowers; these problems are easily avoided through proper maintenance. Grow petunias in full sun exposure and light, well-drained soil with a pH of 6.0 to 7.0, according to the Clemson University Extension.
Nutrient disorders commonly result in the development of small flowers on petunias. This lack of essential nutrients also causes a reduction in the amount of leaves and flowers on your plants that develop later than their usual growth times, according to the University of California Integrated Pest Management Online. This problem is complex, though home gardeners need only perform a few tests and changes to correct this issue. A local county extension agent or other licensed professional can perform a test to determine nutrient deficiencies. Home gardeners may then add the necessary nutrients to soil. However, petunias in need of nutrients might be planted in perfectly balanced soil while experiencing an inability to absorb them. Inhibited absorption is typically caused by poor conditions like extremely wet or dry soil or incorrect pH. Gardeners should make the necessary efforts to create the environment most conducive to petunia growth.
Impatiens Necrotic Spot Virus (INSV)
Viruses often lead to petunia flowers that appear dwarfed or smaller than expected. Impatiens necrotic spot virus, INSV is a virus that attacks petunias as host plants, among others such as fuchsias, calendulas, impatiens and snapdragons, according to the University of Tennessee Agricultural Extension. Other symptoms that distinguish this disease from other problems include stunted growth of the entire petunia plant, flower death, leaf spots and stem cankers. INSV often spreads by virus-carrying pests like western flower thrips that transmit the disease while feeding on your petunias. Preventing INSV is heavily dependent upon close observation of plants and employing control to rid pest infestations. To control an infection that does occur, gardeners should keep weeds at bay, as they attract pests into the garden. Additionally, growers can remove and destroy affected plant parts, though there is no chemical cure for viruses.
Tomato-Tobacco Mosaic Virus
Tomato-tobacco mosaic virus can result in small flowers on your petunias. This virus affects a wide array of other host plants including flowers, weeds and vegetables. As the name suggests, this virus also results in mottled discoloration and blistering on plant surfaces. The virus lives on contaminated equipment and in debris, and is carried by insects. Transfer depends on contact with wounded plant material. Home gardeners should watch for pest infestations and implement management methods when necessary to reduce potential for transfer. Additionally, as the name suggests, tobacco is a carrier of this virus, so gardeners must keep tobacco products away from plants and should sanitize hands and other surfaces after they come into contact with tobacco. As there is no cure for this virus on petunias, growers need to remove plant debris, keep weeds controlled and practice sanitary care of equipment, according to the University of Minnesota Extension.