Mums are a fall favorite with avid and beginner gardeners alike due to their vivid colors and tight, bountiful blooms. Mum-lovers usually can't wait to style their front porches in potted chrysanthemums, and we get it—we adore them, too. But even though retailers start selling annual mums well before fall begins, you may want to hold off on buying them just yet.
“If it’s still sultry and 100 degrees, they’ll only last a couple of weeks—so you’ll have to replace them faster,” says Justin Hancock, a horticulturist at Costa Farms. Justin says he comes across a fair number of customers who can’t wait for the start of fall and begin decorating as soon as mums are available in August. Unfortunately, putting mums out when the weather is still quite warm means gardeners may end up replacing their plants two or three times between when they first start using purchased mums in containers and garden beds and when it gets cold.
For best results, keep your potted mums in the garage or inside your house until temps drop. And when picking out plants at your retailer, choose mums that are still budding and not in full bloom. That way you'll be treated to a longer blooming cycle once you have plants in place.
Two other factors to consider: what type of mums you're buying and where you want to use them. If you're simply hoping to use mums as an annual in a potted display or garden bed, you can opt for florist (or cutting) mums, which are typically grown in greenhouses and primarily used for indoor use. Enjoy them until the blooms die off and then compost them.
Hardy (or garden) mums are a different story. These mums are actually perennials as long as they're properly planted and given the right care. They're best planted in the spring once the ground is free of frost, giving them summer to establish their roots in the soil before they become knockout bloomers in the fall. If you pick up hardy mums in the fall with the intention of keeping them around until the next blooming season, consider using them in pots this year, and bring them into your home over the winter to keep them alive.
Long story short: There’s not a "best" time to put out your annual mums, but you’ll get optimal plant performance in cooler weather. Mid- to late-September is ideal if you want to love your mums for longer.