Garden Mums: Autumn Jewels
The garden mum (Chrysanthemum x morifolium) graces front porches in autumn, flowering in shades of red, yellow, orange, white and pink.
Garden mums have been hybridized for compact growth and to produce plenty of flowers. They typically flower from August to November.
Are garden mums hardy?
As a general rule of thumb, garden mums are not hardy and should be treated as an annual. Chrysanthemums are technically hardy in zone 5-9, but many new varieties have been bred to flower prolifically, and not for hardiness.
That said, there are varieties of mums that are likely to survive the winter. For the best chance of overwintering your mum, try planting a Belgian type. They are compact growers that bloom prolifically and do not require pinching to maintain their nice, compact shape. They also have stronger branching, so their branches are less susceptible to breakage. Buy them early in the season, and try to get them into the ground in September so they have a chance to establish before winter sets in. Most of the Dinter Grown mums we grow in our greenhouse are Belgian Mums.
Basic Chrysanthemum Care
If you want to over-winter a hardy mum be sure to remove it from it’s pot and plant it. Keeping a potted mum through the winter might be difficult. Ideally, perennial mums are planted in August or September so their roots have lots of time to establish before winter.
Mums like full sun to partial shade. If you are planting annual mums they will tolerate more shade, but too much shade will cause their leaves to yellow.
Mums are thirsty plants and require lots of water. When growing them in a pot, water the soil surface until water begins to drain from the bottom of the pot (make sure the pot has drainage holes). Water should drain freely through the soil and out the bottom of the pot. Soil should remain moist, but not soggy. Soggy soil can cause root rot and other diseases.
Hardy mums like excellent drainage. Avoid planting them where there is winter wet.
Make sure you don't plant your mums near a street light or a source of light at night; they need the longer nights to tell them it's time to flower.
Don't cut your perennial mums back until spring. The stems will trap snow and give added winter protection by insulating the crown of the plant. You can also insulate the crown of the plant with mulch or leaves.
Pinch perennial mums in late May or June when the shoots are 6 inches tall to encourage branching and a nice, bushy appearance. Continue pinching until July 4, or more simply, wait until the middle of June and then cut the plant back by half, cutting just above a leaf node (where the leaves join the stem). Not only will the mum fill out, it will also reduce in height, lessening the probability of staking in the fall.
Other Chrysanthemums:
Korean mums (Chrysanthemum sibiricum) are a wild mum with vigorous growth and good branching. They tend to be 4 feet tall with flowers that come in a range of colors from pale yellow and dusty pink to burnt orange
Chrysanthemum rubellum grows 2 to 3 feet in height, and spreads to form open and loose clumps which often require staking and are hardy to zone 4. They are sturdy and easy to grow. Common varieties include: Clara Curtis, Mary Stoker, and Duchess of Edinburgh. Although classic perennial Chrysanthemum is ‘Sheffield Pink', also known as 'Hillside Sheffield Pink' or just 'Sheffield'. It is generally classified as a rubellum.
For the horticulturally-inclined, taxonomy nerds out there — In the late 1990’s taxonomist split the Chrysanthemum genus (comprising over 200 species) into many groups, putting those common mums into the genus Dendranthema. After much discussion and confusion it was decided to reinstate the name Chrysanthemum for all those fall-blooming “mums”, since the name was so widely used.
Read this New York Botanical Garden article for more information.
