Susan,

"The leaves on the stems also turned brown about half way up."

When the lower leaves suffer, the most common cause is a nutrient deficiency, usually potassium. Zinnias grow fast and are heavy feeders, so it is unlikely that your new bed had enough nutrients for them. I feed my zinnias with Miracle-Gro Tomato Formula and my zinnias and tomatoes love it. During hot weather, zinnias also respond well to foliar feeding, once again, with the Miracle-Gro Tomato formula according to the instructions for foliar feeding. The petals on the blooms are much more sensitive than the leaves, so when your zinnias have blooms, cut the foliar feeding strength to one-quarter the normal strength. And/or try to avoid spraying the blooms themselves.

"Our summer was one of extreme heat - 60 plus days of over 100 degrees. I did water them often, but the soil was dry when I did. "

Zinnias thrive in heat. The 60 days of triple digit temps could have contributed to some fantastic zinnia growth if they had been fed (and watered) well.

"Any clues? I [plan] to grow some single flowering types next year, like Will Rogers..."

Will Rogers is a double red dahlia flowered zinnia. It is an old heirloom variety, that most seed companies now no longer carry. If you are interested in single zinnias, the Whirligig strain of zinnias has a fairly high percentage of singles, depending on which seed source you get. This is a picture of some of my Whirligigs this year.

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Those particular Whirligigs were from Stokes Seeds, whose strain runs more to the doubles. The Whirligigs from Parks Seeds have a higher percentage of singles. Single Whirligigs can look quite good, because the single flower form shows off their bi-color and tricolor color combinations to a good effect. I breed zinnias as a hobby, and I prefer un-zinnia-like flower forms, like this example.

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I refer to that zinnia flower form as "toothy". I will probably come up with a better name as time goes on.

"...and need help figuring out what the problems are."

Zinnias are considered easy to grow, so we should be able to help you be successful with them next year. Incidentally, if you are able to post pictures of your zinnia problems, that could help all of us diagnose solutions for your zinnia problems.

ZM
(not associated with product or vendor mentioned or linked)

I am LOVE with your Zinnia 'Toothy'!! Did the butterflies love it, too?

I grow the Zinnias for the butterflies and they prefer single flowering varieties. I used to have a pink flowering single that the Monarch butterflies adored.

Any suggestions are welcome. Thanks for the input on fertilizing. For some reason, I got it in my head that they do not need/like rich soil. I couldn't have been more wrong.

Susan

My Zinnias did great this year, both my Benary Giants and Zowie Zinnias. I live in Louisville, Ky. and I too had 40 days of near 100 degrees. The Zinnias have no mildew yet and are still going strong. I cannot wait until next spring to plant them again. The butterflies love them too.

Betty

Betty, congrats on the performance of your Zinnias! My Zinhias planted in 2 other locations did fine. But, they have much better soil than the ones I had problems with. Can you tell me what varieties you grew?

Susan

I had some brown leaves on my Zowie Yellow Flame zinnias but it was so hot and dry this year, I was blaming that. Maybe my soil needs some potassium as well. Whatever it was, Scarlet Flame tolerated the conditions a little better than Zowie. Zowie had more blooms per plant but had some spotty dry leaves. Scarlet Flame looked healthier but not quite as many flowers. The butterflies liked both of those a lot.

My local source for Scarlet Flame went out of business this summer. : ( I will have to order them next time.
I haven't grown Will Rogers so I can't say how well it would attract butterflies. I love Zowie but they're expensive for zinnia seeds. I don't think I'll order those again until the price has come down.

Hi Christie,

I only purchased one pack of Zowie Zinnias, and that was all I needed. Each plant gets so huge, and I actually gave 4 plants away that I started in pots. I put grass clippings around all my flowers in my backyard and boy does that make the flowers beautiful. It breaks down fast and gives nutrients to the flowers. I use pine needles as mulch only in my front yard.

i dont claim any proficiency in zinnia ..

but our very cold may ... stunted everything in the yard ...

and since that is planting time in my z5 .. the zinnia in particular.. had an off year ...

EVERYTHING that was seed started.. struggled ... and was 2 to 4 weeks late ....

the 6 weeks of drought and near hundred degrees.. on very small late-starting plants did not help either ...

ken