Crysthanemums, fondly called “mums” by many a passionate flower gardener, are arguably the floret of fall. They appear in everything from Halloween door wreaths to cooler-weather bridal bouquets. The trick to getting the most out of your fall mums is avoiding buying chrysanthemum plants already blooming. Why? They only stay in bloom for about three weeks. If you usually buy a plant in half or full bloom at the end of summer, you’ll only have pretty petals for the first month or so of fall.
Mums are perennials, but many nurseries (and, therefore, gardeners) treat them as annuals — primarily for sales reasons. What’s the difference? In the annuals vs. perennials debate, the former lasts only one season; the latter, many years. A cold-hardy mum planted in spring will keep blooming year after year, but a garden center plant may not last the winter as it’s cultivated for abundant flowers, not longevity. Once planted and with the right conditions and care, you can expect a hardy chrysanthemum to live for about three to four years, possibly longer.
To buy or grow?
If buying mature chrysanthemum plants online or from a garden center, look for mums covered in buds, not fully-fledged blooms. Buds take six to ten weeks to turn into flowers. Aim to purchase the plants with buds in late summer; you’ll get blooms well into the middle of fall. You can also look for late-blooming varieties that typically flower in October and beyond. The daisy-like “Hillside Sheffield Pink,” available at nurseries across the U.S., is a good example.
Another way to ensure long-lasting mum blooms is to grow the plants yourself from seeds, seedlings, or cuttings. Chrysanthemums started in winter will be ready to plant outdoors in late May in most U.S. hardiness zones. Alternatively, you can sow the seeds directly into beds or pots in September and October. Just keep in mind that growing your mums this way is a long game, and it may take a number of years before they hit their peak.
Overwinter your chrysanthemums
If you want to grow mums in containers and keep them thriving through successive autumns, you need to learn to overwinter them, as potted plants don’t enjoy the insulation benefits of the ground that planted mums receive. While mature, planted mums can live with temperatures as low as 20 degrees Fahrenheit as long as you provide a nice blanket of mulch, you’ll need to bring container mums indoors for the colder months and leave them in a cool, dark location. Then, you can gradually re-introduce them outside once the temperatures warm.
There are other tricks to get a more colorful show from your chrysanthemums late into fall. Make sure to deadhead your plants, which involves cutting off flowers after they die. If you’re growing hardy chrysanthemum varieties, feed your plants in the spring with a 5-10-5 or 7-6-5 garden fertilizer; you don’t need to do this for nursery-purchased plants treated as annuals as they’ll already be fertilized. Make sure, too, you leave about 12 to 18 inches between each plant. Mums hate overcrowding and won’t bloom well if they’re feeling cramped.
