There's an Annuals forum that might be better suited for this question. Mine still look great as well, but I know they'll likely be gone within the next month after cold temps arrive. Never easy to say goodbye.
Annuals Forum

So true. Thanks for the suggestion. I will look on that forum.

I keep old, worn-out sleeping bags and comforters around to use to cover the garden in the spring and fall. No reason why that wouldn't work for marigolds as long as you aren't expecting rain during the night.

BTW, you can deadhead the dried flower heads and scatter the seeds where you want flowers next year for free, healthy, hardy seedlings. Nowadays I only buy marigold packets when I see an unusual variety I'd like to try growing.

We get cold snaps all the time - as you probably do. We have to be careful because a forecast of 37 degrees F usually means 30-32 degrees at our house. Taking that into consideration - we cover flowers with a frost blanket when the temp at our garden is expected to be 35 degrees or below - if we don't want them to be damaged. It is too hard to predict just how cold it will be - so we allow a fudge factor (35 degrees) to be safe. There are so many variables that can affect actual temps on the plant! We remove the blanket after the snap and the plants continue to do well until the next cold snap! When the frost blanket no longer protects the plant from frost - game over - haha

Thanks. Have you ever left the blankets on for a couple of days or do you take them off and put them back on at night.

Schneibs - we look at the weather pattern and decide - but usually we leave them covered during the day too during a cold snap. We have left them covered for up to a week at a time because the cold snap also brought cold (and snowy) daytime temps with little or no sun. We have to stake the cover in our climate because of the wind - sometimes I will remove the stakes on three sides and fold the cover off the plants during the day to let them have some sun - it all depends on weather conditions. I have never had a plant respond negatively for leaving the frost cover on too long but I have had many plants get damaged because I was negligent in getting them covered quick enough or removing the cover too soon.