Garden mums, often just called mums, are the gardener’s harbinger of fall. Their bronze, yellow, and orange hues brighten up patio containers and flower beds. They also come in whites, pinks, and purples if you aren’t into the sunset tones. They are incredibly floriferous. They will continue to bud and open flowers until first frost.
You might think that because they typically stop flowering when it gets cold, mums are annuals. However, this is only partially true. Most mums are indeed grown as annuals, though technically they're perennials. When planted in mid fall, they often do not develop enough roots to survive the winter. If you live in a mild climate and you plant mums early in the season (think late summer, not fall), they MIGHT develop enough roots to survive the winter and earn a spot in your perennial garden. This is why garden mums are sometimes referred to as hardy mums. If cared for properly, they are usually hardy down to Zone 5. If you really wanted to make sure your mums survived the winter, you would be better off planting them in spring after the last day of frost. By letting them grow all summer, they grow a much better root system which helps them overwinter better. However, it is difficult to find mums in the springtime.
It's easier to grow mums as annuals, and here's why. When frost does hit, the stems and flowers will die back. The roots will be fine, but in colder areas you will have to protect those roots. The best way to do that is to leave the dead stems on the plant, and pile some mulch around it. The dead stems and mulch create a protective microclimate that will keep the area immediately around the roots warmer than it would be without that bit of protection, but then you have to look at dead stems and odd piles of mulch all winter. While some plants still look good past their prime with pretty seed pods or similar features, mums look awful with dead stems. It feels extra sad because of how beautiful and heavily flowered they are immediately before this twiggy phase.
If you are a mum aficionado and you want to special order your mums and care for them in your perennial garden, go for it! However, if you’re like most people and you just want to enjoy their ephemeral fall beauty, here is how:
Garden mums lend themselves really well to mass plantings. Pick colors in a color family (red, bronze, and yellow for example) to make a beautiful flower bed. The mounds of vibrant color are delightful. They also plant well in containers. Mix them with ornamental kales and marigolds for beautiful combos. Or, you could have a mum centerpiece surrounded by gourds and pumpkins for your last outdoor parties before winter.
Garden mums often have vigorous roots. This root ball needs to be broken up when planting in the ground or in containers. This will help the plant take on enough water post-transplant so as to avoid stress.
Garden mums like full sun. Plant them in a sunny spot that gives them 6+ hours of direct sunlight a day.
These guys are heavy drinkers. When you first plant them, make sure to give them a good soak, then water every other day or whenever the top of the soil gets dry. Mums do not like dry down cycles. Do not let them wilt. Try not to get water on the foliage in order to prevent disease.
Because we are growing them as annuals, there is no need to fertilize!
Pests & Diseases
They can get a few fungal diseases, powdery mildew, rust, and botrytis. The best option for these diseases is prevention. Avoid getting water on the foliage and flowers. In the fall, it becomes increasingly important to irrigate in the morning so the plants have the whole day to dry off before night. Pay attention to the weather forecast and try to time your watering to avoid watering on cloudy and foggy days.
They also get a few pests, mostly leaf miner, aphids, and spider mites. Clip off damaged/infected foliage. If the infestation moves beyond a few flowers, use a spray of insecticidal soap (early in the morning on a nice fall day).
Almost none! If you are craving some garden chores, you can take some clippers and snip off the spent flower buds to make room for more. However, this isn’t strictly necessary as the plant will grow up and cover all the spent flowers anyway.
In the garden world, nothing screams fall more than a garden bed full of mums. Sip your coffee and stare at the beautiful mounds of color in the crisp autumn air until they peter out.