Nothing says fall like chrysanthemums. Although Moms are perennial plants, in the north of the United States most growers call them to fall mums or garden mums, because they are not hardy. Once the winter cold settles in they have a 50/50 chance to survive, and they hardly do.
Mums are mostly bred for flower size, flower color, and plant shape. They look fantastic and can fill up our gardens with spectacular showy flowers, but much of the hardiness that mums used to have, has been bred out during their production.
Unless you live in a warmer climate, where the plant can thrive even if they lose all their flowers, it is better to treat them as annuals. You have to get them in the ground early in the growing season for them to come back.
Mums should be planted by August if you want them to make it through the winter. If you try to plant them in October or November, they won’t have enough time to root and get established in the soil, and the roots may heave up out of the ground.
Even if you get the mum to survive the winter, you will have a plant without flowers taking up space in your garden throughout the summer. So, are they annuals or perennials? The answer is, depending on where you live and the reason why you plant them.