How Big Do Chrysanthemums Grow?

Florist Mums

• Nurseries usually label the mass-produced, foil-potted mums as simply “Chrysanthemum.” The flowers are any and every color, from lavender to bi-color to bronze, and they are usually eye-catching pompom or anemone forms. The potential size of these mystery mums ranges widely. Because most nurseries pinch back the growing mum to produce tidy mounds, the potted size is not an indicator of future growth. As a general rule of thumb, large-flowered mums are also larger plants, growing up to 3 feet tall and nearly as wide. Likewise, smaller-flowered varieties may remain half that size.

Small Mums

• Cushion mums form neat, well-mannered plants that rarely grow over 12 inches tall and have relatively small, 2-inch button flowers. These are useful in borders, along walkways or tucked into rock gardens. What cushion mums lack in size they make up in number: a cushion mum in full bloom seems to have more blossoms than leaves. While some cultivars have specific names, such as the orange-bronze Inca, many cushion mums are anonymous and identified only through their color.

Medium Mums

• If you are lucky enough to find a nursery with named cultivars, you may find a medium mum with large, 3- to 4-inch flowers on a 2- to 3-foot tall plant. Many of these medium-sized mums produce surprisingly large flowers, although some, like the vibrant purple Royal Pomp, have smaller, scented blossoms. The flower form ranges widely. Zonta produces bronze pompoms, similar to a cushion mum, but Rosy Glow has large 4-inch flowers with incurved petals.

Tall Mums

• Tall mums grow up to 4 feet tall. The Maxi-Mum, a trademarked variety, stays below this height but spreads up to 30 inches wide. Many of these varieties require pinching, or pruning plant tips with your fingers, to keep the plant from becoming leggy. Large mums are relatively rare in flower gardens, but named varieties offer big, show-stopping flowers from summer until late fall. Gold Country has 4-inch double flowers in late summer, while Centerpiece flowers have maroon, pointed petals and a deep yellow eye. Give tall mums plenty of room -- like most perennials, they grow larger the second year than their first.