If you prune them back they will come back with a second flush of healthy growth and blooms. The fungus invades the roots, and takes in the water before the petunias can. By the second week the leaves turned yellow and brown I do have flowers but I wouldn’t say alot of them. Petunias are susceptible to Fusarium, which is a fungus rather than a true disease. are easy-care, flowering beauties usually grown as annuals and discarded at the end of the season. Below are common diseases affecting petunia plants: Root, Stem and Crown Rots – Root, stem, and crown rots commonly affect petunias planted in areas of poor drainage or that are chronically over watered. ! Water and fertilizer are key to growing healthy and attractive hanging baskets. I water it well. I know its a good drought plant so Im not sure which is it. Regular petunias (not Supertunias or Wave Petunias) need to have the developing seeds that are under the wilted flowers snipped off in order to keep blooming. White Mold Sclerotinia sclerotiorum. For the past several weeks, my wave petunia has been getting more & more sparse, and the leaves are turning brown and dying. Yesterday there wasnt rain and I didnt water. The leaves on the plant are yellowing (with brown veining). Petunias' foliage will turn brown when they are at a certain stage in their growth cycle. This plant looks like it needs deadheading as well. Many are, in fact, herbaceous perennials that thrive in U.S. Department of Agriculture plant hardiness zones 9 through 10. All Topics Topic Home & Garden Gardening & Plants » Wave Petunia leaves turning brown martina59 Posts: 63, Reputation: 3. Petunia foliage turning yellow is never a good sign. I drowned the whole yard Tues and Wed. it poured all day. Petunias are tender perennials grown across much of the United States as summer annuals. I have a hanging basket of Supertunias in full sun. Help! Leaves wilt in too dry soil. Petunias (Petunia spp.) They did wonderfully well all summer long. Is it becuase theres not enought water or too much? The leaves turn bright-violet, their edges curl, on the surface appear brown spots with excessive light as a result of sunburn. Leaves wilt despite regular watering and stems may begin to soften. Junior Member : Aug 19, 2008, 05:34 PM Wave Petunia leaves turning brown. If leaves have yellowed, become brittle or begun to turn brown, cutting the petunia back may revive it. Some of the stems don’t have any leaves at all. Jacks Petunia feed at the nursery thats what the woman suggested. Leaves on the entire plant or single branch wilt and turn brown; Stems turn tan to off-white where infected; Fluffy, white cotton-like fungal growth may been seen growing on the discolored stem when humidity is high As the woman said they look leggy should I cut those back. Brown leaves. You may also see yellowing or browning of the leaves as well. I pick the leaves off as they die I’ve also fed the plants. Petunia Diseases. Diseases: Fungal diseases can cause brown spots on leaves too, as the fungus attacks a localized spot on a leaf (usually where water is allowed to sit on a leaf, or there is wound on the leaf surface) causing the cells to die and turn brown. have several baskets of wave petunias. 3. Just like an under-watered plants, this leads to wilting. Recently the leaves turned dry and brown. Its about 101 out so its very very hot. My petunia's leaves are turning dark brown...? Without adequate water, petunias may cease blooming, or foliage may wilt and die, within a day or two during hot, dry weather. Could it possibly be getting too much sun? The leaves turn yellow and fall off when the soil is viscous due to excessive watering. 2. The leaves on my Mexican Petunia are turning yellow and dropping. WIthout seeing your plants it … Petunia Leaves Turned Brown and Dried Out. It's not looking good. What could have caused this? They get sun from around 10 am until it sets. The ends of the leaves twist in too dry air.