Garden Mums for the Home Garden

Introduction

Garden mums (Chrysanthemum x morifolium) are known for their vibrant blooms and resilience and are a popular choice for adding color to gardens and landscapes in the fall. They are one of the best perennial plants for late summer and fall bloom. They are important in many Virginia landscapes, flowering during September and October when few other plants are in bloom. They bloom over a long period, exist in a very wide range of flower forms and colors, and require a minimum of care.

While they are typically hardy in zones 5 to 9, individual cultivars can vary in cold tolerance because of their complex genetic makeup. Winter survival may also vary with location, culture, site, when they were planted, or winter severity.

Garden mums can be planted in many areas around the home. Tall varieties make excellent background plants and can be used for cut flowers. Medium- height varieties are used for pot plants, planters, and in containers on porches and terraces. The "cushion" mums (low-growing varieties) can be used for edging a flower border.

Chrysanthemums can be transplanted at any time, from early spring until they are in bloom. Some homeowners move them when in bloom to fill vacant places in their flower beds or borders in late fall. But the best time to transplant is before flower buds set in late summer.

Culture

When growing garden mums for the first time, it is advisable to buy well-rooted cuttings from a reputable dealer, likely from the internet, in spring to early fall. The reasons are that the cuttings are insect-and disease-free upon arrival, available when desired, desired varieties and number of plants can be obtained, and the cost per cutting or plant is usually small.

Garden mums may survive and bloom well in one location year after year, but they usually are best in the first year and then start to decline. Therefore, it is desirable to use new plants each year or every other year.

Garden mums should be planted in May or early June. Plant in full sunshine where they will not have competition from other plants and where the drainage is very good. Plant in fertile, highly organic, well-drained soil. Set the plants 18" to 24" apart. The spacing depends upon the variety and whether a few exhibition-size blooms or numerous smaller flowers are to be produced. Mulch to help retain soil moisture and control weeds.

Tall, cut-flower types should be staked to keep them upright because they tend to break or fall over. The lower-growing varieties do not require staking if they have been properly pinched, fed, and watered.

The quality of the plants and the quality and quantity of flowers depends on the care given to them during the summer. The important cultural practices are pinching, feeding, and watering.

Pinching

Pinching is removing the tips of the soft new shoots to induce the plant to branch. When the plants reach a height of 6" to 8", pinch-off or cut-off about 1/2" of the tip. This makes lateral or side shoots develop. When these branches are 8" to 10" long, remove about 1/2" of their terminal ends. Some varieties may need a third pinch if they are extremely vigorous, but two pinches are usually enough. Pinching should not be done after mid-July. Garden mums are short-day plants and will be developing their flower buds at this time. Late pinching could delay flowering so that the flowers don’t open before the first frost.

Fertilization

The amount of fertilizer needed to produce top- quality garden mum flowers varies considerably, depending on the soil. Plants with heavy stems and thick, dark-green leaves are probably getting all the nutrients they need. Small, light-green leaves and spindly, weak stems are probably indicators of something lacking in the soil. A feeding solution of a tablespoon of 5-10-5 fertilizer per gallon of water applied every week to ten days, until flowers show color, has been a successful feeding program. It is better to apply a weak fertilizer at frequent intervals than a heavy one infrequently.

Watering

A garden mum in full growth needs lots of water. During droughts, water the plants when the soil becomes too dry. Soak the ground thoroughly every week or two so the plants keep growing continuously. Leaf diseases are less troublesome if the foliage is kept dry, especially during the night.

Flower Types

Garden mums not only come in a wide range of flower colors, but they also have a variety of flower types. The common flower types include Anemone, single, pompom, spider and decorative.

• Anemone – Prominent center of disk-florets‌
• Single – Classic, daisy-like appearance with a yellow center
• Pompom – Globular flowers
• Spider – Long, tubular flowers‌
• Decorative – Large to medium full-looking blooms

Flower Bud Removal

To enhance the flowering of your garden mums, you may want to include a flower bud removal practice. The three main flower bud removal practices include zero bud removal, disbudding, and center bud removal.

You can grow mums without doing any flower bud removal. This practice is called zero bud removal (ZBR). This may result in slightly smaller flowers than if you practiced bud removal.

Disbudding (DB) is the removal of lateral buds so that the terminal flowers will be larger. However, it is not practiced with most modern hardy garden chrysanthemums. This practice is usually used on tall varieties, so you end up with one large bloom per stem, great for cut flowers. Disbudding is done as soon as you can handle the lateral buds.

Center Bud Removal (CBR) is the removal of the center (or terminal) bud on each main stem, leaving the lateral flower buds. This is done as soon as the center bud has separated from the lateral buds surrounding it. Be careful when removing the center bud to not damage the lateral buds.

Propagation

Chrysanthemums are relatively easy to propagate from cuttings or by division of the old crown. Only healthy plants should be used for propagation.

Divide early in the spring before new growth begins. Dig the clump and break or cut off the shoots from around it, leaving a mass of roots on each piece. Discard the center. It is last year's roots and stems and is of no value.

Softwood cuttings from the tips of the new spring growth can be taken and rooted. When the new growth is 6" to 8 " long, remove about 3" or 4" of the tip. This is called a tip cutting. Remove the lower leaves for easy insertion in clean sand, vermiculite, perlite, or various combinations of these materials.

Keep the propagation medium moist but do not overwater. In approximately two to three weeks, the cuttings should be rooted sufficiently to be transplanted to containers, flower beds, or gardens.

Overwintering Potted Hardy Mums

While garden mums are typically hardy in zones 5 to 9, individual cultivars can vary in cold tolerance because of their complex genetic makeup. Winter survival may also vary with location, culture, site, or winter severity. Because of these reasons, they are no longer typically called hardy mums, but garden mums.

Garden mums are versatile plants that can typically survive our winter conditions here in Virginia. Still, they need the right care to make it through the colder months. To ensure these perennials thrive and come back strong each year, proper winter care is essential.

To ensure good root development for your garden mum, it likely needs to be planted in the ground/garden in late August or early September. This often means buying mums in bud rather than showing color or in bloom. The later the mums are planted, the lower the survival rate. A late-planted mum will not develop a good root system in the garden soil. Because of the short-day conditions of the fall, mums are naturally programmed to be flowering at this time of the year, not producing roots.

For more information on overwintering mums, visit https://ext.vt.edu/lawn-garden/Timely_Topics/mums.html.

Acknowledgement

Adapted and revised from an original publication authored by Paul L. Smeal, Emeritus Extension Horticulturist, Nursery Production, School of Plant and Environmental Sciences, Virginia Tech.