My wife oversees the Deity flower garden which produces flowers for garlands and vases. As the end of the frost free season is approaching, the clock is winding down on how much longer marigolds will produce. To extend the season we bought 108 chrysanthemums. They can take a frost and keep producing.
We will try to extend the marigolds as long as possible by covering some with floating row cover to fend off the early frosts but the mums will go later into the season.
I found a local guy who is a school teacher and grows mums as a sideline. He sold them to me for 2/3s the cost of what I could have bought them at a big box store.
The other thing is that he assured me they are hardy mums. When you buy them at a big box there is no such assurance. With hardy mums there is a chance they will over winter given proper care and then come back next year.
I also tried an experiment growing on some late planted calendulas (pot marigolds).
They are also frost hardy and can extend the growing season. Late year I tried growing some but planted them at the same time as other flowers in the spring. By the time fall rolled around they were played out. This year I planted them the 1st of July an d they are coming into full bloom now, which works out much better.