Hi grny28, I am going to refer to The Ortho Problem Solver, seventh edition on this, because I am no expert on Petunias (zinnias are my "thing"). The book's coverage on Petunia problems starts on page 262 and continues onto page 264. It has articles on Gray Mold (everywhere in the US), Smog Damage (limited to relatively small coastal areas), Caterpillars, Cutworm Damage, and the last article on Crown and Root Rot (everywhere in the US) seems the most likely culprit. Crown and Root Rot is caused by Phytophthora (I don't think you can say that without spitting a little), a fungus that lives in the soil. It initially attacks the roots or stem at or just below the soil level. The dark dry decay of the lower stem tissue and roots reduces the flow of water to the leaves and flowers, causing the petunia to wilt and die. Crown and Root Rot is common in heavy poorly drained wet soils. The fungus (Phytophthora) is spread by contaminated soil, transplants, and tools. The solution is to remove and destroy infected plants and all the soil within 6 inches of their roots. How do you destroy soil? Well, I guess you could throw it into an incinerator, but I would just put it a plastic bag and send it to the landfill with the rest of the garbage. To prevent a recurrence of Crown and Root Rot, you should improve your soil drainage and drench it with a fungicide containing Captan. That's what the Ortho book says. Repeat the drench monthly during the growing season and let the soil dry out between waterings. I try to avoid problems of this sort with my zinnias by adding a lot of sand to my garden soil to create a sandy loam, and I add Perlite to my indoor growing medium to increase its drainage. "They were planted in larger containers along with other plants that are fine, What are the chances of a disease from so many different nurseries?" Many plants aren't susceptible to Phytophthora, and the problem is in your soil or growing medium, and not at the different nurseries. ZM (not associated with any product or vendor mentioned or linked)

Your roses might not be dead; there could be live cane below the soil line, or at the soil line. I would prune off the dead wood, and see what happens this spring. I'm not familiar with Don Juan, but it might be prone to dieback in a cold zone.

It's the old adage that "you can't grow rhubarb (or tulips :) in the south". Supposedly because it doesn't get cold enough in the winter and gets too hot in the summer. But really it is the lack of sufficiently cold winters that the plant needs to go dormant for a period. Then it has to deal with hot humid summers. Here for example, my ground never gets cold enough for it to grow as a perennial. Refused to believe it and tried for years to keep it going. But it will work for me as long as I keep it in a big container since the soil in the container gets much colder than the ground and come hot summertime I can move them into shade. I have 2 plastic 55 gallon drums cut in half that are full of rhubarb. Going into their 5th year now and going strong. Dave

Could have been any number of reasons why it died as stated above, we don't know what conditions you gave it...other than 'probably' poor soil. My first thought would be starvation from being in the same pot/soil for o19 years. I assume by 'dirt' you mean potting mixture? I know in the US garden soil is referred to as dirt on occasions. Etiolaion could also cause total collapse. If it's been in the same pot for 19 years, either it was way overpotted to start with, or at its end it was too crammed in and rootbound as I'm assuming it had grown somewhat? Was it ever fed, how often was it watered, did it get a teaspoon of water or a 5 hour soaking each time, did it have adequate light, had it been moved into a draughty area for some reason, where was it kept? I know say it thrived but without pics we can't even be sure of that....have you any pics of the deceased? There is a vast difference between someone's vision of a thriving plant and one that is actually only clinging to life in reality. If you decide to buy another one, best advice is to at least change its mixture more frequently than you did do. However, please give us more info, only then 'maybe' we can guess better. Gill