Petunias Wilting, Dying - Knowledgebase Question

Gainesville, Fl
Avatar for bmcdade07
Question by bmcdade07
May 15, 2010
I saw your answer about potted petunias that wilt and die one by one. You said that it might be a fungus in the soil. My potted petunias were doing great, blooming, etc. but parts of the plant are now wilting & dying. How can I determine if it is fungus, and what type? Can the soil be treated? Can the fungus be killed? I do not see any pests (such as slugs) around the petunia plants. Thank you.

WI (Zone 5b)
Avatar for davidg2156
A comment from davidg2156
June 9, 2018
Both my petunias AND the impatiens succumb to this, but usually not until mid to end of August when the humidity is so great here in the Midwest. I always consider it inevitable...I can't water without getting the tops wet, unless they are in pots. Those seem to last longer.

Jacksonville, FL
Avatar for Gadsden
A comment from Gadsden
June 9, 2018
The same problem happens to me and I'm in NE Florida, so maybe we can assume climate has nothing to do with it!
The theory about watering from above is illogical to me, because in Nature that's generally the only way plants get water.

Avatar for gettysburga
A comment from gettysburga
June 25, 2018
My petunias were doing the same thing. I simply pruned off the spinney and dead growth, dead-headed, added about 2 inches of fresh soil to the top and some fertilizer for flowers. They are doing amazing now!!!! You should see them. Very full, healthy dark green foliage and huge mound of flowers. It was such an easy fix. I usually have to do this in August but because heavy rains have washed away the fertilizer and soil I figured I should do earlier. I will probably have to do it again in August or maybe sooner if this rain continues. They will love you for it!

Answer from NGA
May 15, 2010
Photo by jmorth
Petunias are susceptible to Verticillium wilt and it's easy to diagnose. Cut one of the stems and look for dark colored streaking within the tissue. You'll want to cut off an affected stem and then cut it in half long-ways. The streaking will be within the vascular tissues. If the cause is indeed verticillium, you should change the soil and clean the planters thoroughly with a 10% bleach solution before replanting petunias.

If you see no obvious signs of fungus or rot, your Petunias may be wilting for other reasons. The plants may simply be showing stress from heat and humidity. If this is the case, pinch out the wilting stems and foliage (back to healthy growth). Try to keep water off the tops of the plants, and allow the soil to dry somewhat between waterings. These measures should decrease humidity and encourage healthy new growth.

Good luck with your petunias.

Morrisonville, NY
Avatar for DDragon121016
Answer from DDragon121016
June 10, 2018
So this might be something everyone knows, but with my experience with petunias esspecially in pots are you need to water every morning and make sure the pot drains. If the pot doesn't drain i fear for root rot. Also watering in the morning is typically better than watering after work because once the afternoons start to get colder your soil could be too wet for the temp. Also petunias like food. Your standard miracle grow would do the trick, but at my local garden store they sell petunia food. Doing this 2-3 times a week or whatever the box recommends will go a long way. Also deadheading the plants are usually a must. I don't plant petunias anymore because you have to deadhead them, and they just get too high maintenance, but i know my petunias died or wilted if i didn't deadhead them. If I did stay on top of deadheading them, they grew into this great big healthy plant with lots and lots or beautiful flowers.

Name: Marcia Kuma
Buffalo NY
Avatar for Owllady
A comment from Owllady
June 10, 2018
I've never deadheaded petunias in my life, I've always found them to be mostly self-cleaning. I do find it helpful to give them a shearing back in mid-summer, cutting a third to half the plant away. That seems to rejuvenate them for the rest of the summer.

The advice on watering is good I think. Also some folks - me included - have a tendency to overwater their garden and too much water can cause problems. When I'm more careful about how much I water, my plants do better.

Name: Frank Mosher
Nova Scotia, Canada (Zone 6a)
A comment from fwmosher
June 12, 2018
Just one thought about not deadheading - the flower will fall off, but leave behind the start of a seed pod, and that's what should be deadheaded, otherwise, it saps the plant of energy to put into new flower growth.

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