Hi merryd,
If I were you I would cut back the zinnas to a set of new leaves,(maybe 3"), water them good and see what they do, What have you got to loose, they were a bargain. I live in zone 5 and mine still have new buds on them so I cut them back, this will promote new growth and blooms.
Good luck!!!
Marsha

Annuals that have been in a cell pak all summer with spent bloom will not recover from lack of space and nutrients. They have completed their life cycle in poor conditions and will die...not a bargain. You're lucky if you get one to bloom again. Sorry for the seeming negativity, but this is life/death. Chalk it up to experience. Start fresh next summer.

I forgot to answer your frost question. Zinnias are tender annuals that die with frost. You have to start with new seed and new plants each summer. They're worth the trouble!

Thanks for the replies. They are actually in 8" pots with two plants each. The sick ones remind me of tomato plants that have reached the end of their usefulness-pale leaves with little rust speckles that turn crispy and the stems eventually die back. I take it if the whole stem looks dead now there will be no growth coming from the bottom? Would that be the case even early in the season? would some fertilizer help? I read they do best with at least 6 hours of sun-I don't have that much. Some areas get about 4-5 in mid day, but where I'd like to put them get less. I'm also thinking of future plantings.

Zinnias are a full sun plant. They can be kept going all season long if they are routinely dead-headed, but I honestly don't think that you would be satisfied with their performance with only 4 hours of sun.

I'm disappointed at garden centers that put something like this on sale in September. It is a very poor business practice. Annual losses should be figured in as part of their overhead.

I am no expert, but when Zinnias start down, they are done.

Some of mine take a long time to do that, others do it prety fast depending on the water and year, etc. (I think they are susceptible to some kind of fungal disease, and when they start getting brown and crispy - lights out.) Last year I had a big fancy one in a pot and sprayed it with fungicide all summer. Waste of time, money and space.

That's why I switched over totally to the profusion zinnia series. I have had flats of them melt clean to the soil and then spring back from a stub. No fungal problems and they hang in there through the heat of summer and get nice again in early fall. I also think there are few real "bargains" in annual plants put on sale late in summer. Most of them don't resurrect well.

Since zinnias are so easy from seed, I'd skip buying plants and plant seeds directly in the garden or plant the seeds in your own pots and I think you'd have more success. With plants that are very easy from seeding, such as zinnias, I think people waste their money buying plants, especially if the plants have been neglected and are past their prime.

I second the idea of growing them from seed. I have a bunch in a long border that have been simply incredible all summer long and are still going strong. Simply my best plant this summer.

thanks again for more input. I'm not sorry I bought them they were pretty while they lasted and I've learned something I wouldn't have otherwise. I'd never been a fan of zinnias because I've usually seen them displayed in mixes of colors where I prefer larger clumps of the same color. This Coral Dreamland appealed to me because of the varying shades of bright coral-pink maturing to salmon.

AS I looked around at more yards with them I can see that they do seem to die out like tomatoe plants do, so the ones that have gone or nearly so will be dumped and I'll lok into seeds for next year. Can I get seeds from these plants?

I wouldn't trust seeds from malnourished plants. They may be deformed, sickly or not even viable. Seed catalogs and garden centers have plenty of varieties, and you can get all one color if you like.

I've become a zinnia fan in recent years thanks to the wonderful improvements in breeding. Like Calliope, I will grow Profusion every year from now on. They performed flawlessly in the garden and in containers. No sign of any black spot or powdery mildew all season long.

I also recommend the little Crystal series for a constant mass of yellow, orange, or white flowers. Again, these were amazing in the soil or in containers. Tiny little flowers!

Try the Magellan series for those big zinnia blooms, but great disease resistance. I had some problems with black spot in containers, but not in the garden (heavy clay soil). They didn't slow down all summer long.

I grow all my annuals and perennials from seed. It's the only way you can be assured of finding the best hybrids and the best selection!

Here is a link that might be useful: {{gwi:24027}}