Division. One of the simplest ways mums can be reproduced is through division. Over the years, mum roots become tangled and clumped, making nutrient, oxygen and moisture absorption difficult. As a result, the mums do not produce as many flowers as in past years.

Do mum plants spread?

Spreading Mums Chrysanthemums are often grown as annuals, especially in climate zones north of USDA zone 5 or south of zone 9. However, mums grown as perennials spread rapidly and may become unsightly and overgrown.

How much do mums spread?

A: Hardy chrysanthemum plants can grow 1 to 3 feet tall, depending on the cultivar, with a spread sometimes equal to the height. To keep them growing optimally, they should be planted in a full-sun location that receives at least six hours of direct sun per day.