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)

What is the water like that you are using now? Could that be the problem? Asking because I have large amounts of iron in my water. None of the plants mind and grow well here as long as I repot often and use a light mix for everything because the soil seems to compact much faster and gets rather funky after a length of time. Before I did this nothing lived all that long...Years ago too much lime was an issue where I grew up, pots were always heavily crusted with white...

i dont know.. but one thing for sure.. it has nothing to do with ONLY too much water.. because they do the same for me.. with too little water on high drainage mineral sand ... after being fully established ... i also wonder if they are not just very short lived .... do you ever see pix of large plants [which of course we will as soon as someone wants to prove me wrong.. lol] .... [but then.. did iseli grow it big .. and ship it to dave .... meaning he may have skipped all the 'hard part'] the finally.. there is the theory that dead needles accumulate on the inside.. to the point of the rotting material causing bacteria .. molds .. mildews .. which eventually weaken the plant ... i will leave the more scientific explanation to others .... one thing for sure.. they will suggest you go anal on them every year and clean them out ... i doubt you will get a proven theory ... i predict it will be more along the lines of my speculation ... now all that said.. you dont mention if these were new this year .... if so, add the following variables .. shipping and transplant shock.. along with hardening off to your sun [dont recall where you are] .. as compared to iseli .... and perhaps whether or not the tiny babes are shadehouse protected .. and then you slam them out into much more intense sun ... bottom line.. based on all those variables.. WHO THE HECK KNOWS .... ken ps: honestly now.. has anyone grown one of these from tiny to big.. ???? pps: i wonder if the rocks retain extra heat.. and have some negative side effect ... on plants that grow less than an inch per season ... i mean really.. there isnt much room for error.. if you fry all of this seasons growth ... compared to say a pungens which puts out 18 inches of growth, when happy ... all your damage is near a rock .... and hot rocks.. deep into the night.. can increase molds and mildews.. and all the other bad stuff.. they may not be cooling off enough at night???? [at least i think that is a rock in the first 2 pix]

Arthrum: good point, the temps in my house are only kept above 65 degrees, but it still seems that some temperature hardy plants still show dislike of my repotting... Dbarron: oh my! Sounds like a tragedy! I get upset enough when I break of a new shoot! Vtandrea: thanks for the suggestion! I'll definitely try it on one of my oncidiums! Jane: I live in the Oakland hills in the SF Bay Area. I grow almost all my indoor orchids in the same spot, positioned around a fireplace to control the amount of light. The facing of the house isn't the best. 80% of the light is late morning to afternoon sun . 90% of the windows are west facing :( like the house... The problem might be I repotted at the wrong time. I didn't a lot of reporting in the winter/ late fall (whoops...)