How to Propagate Chrysanthemums

Chrysanthemums shine in late summer and fall, adding fresh color to span the seasons as other bloomers fade. With varieties in different forms, colors, and flower shapes, they bloom in sprays, with many small flowers, or as large-flowered selections with showy, single blooms per stem. If you’re catching the bug to add hardy chrysanthemums to your garden, there are many ways to propagate and enjoy these easy-care perennials for seasons to come.

Mums are an asset with attractive, dense, deep green foliage throughout the growing season. Depending on plant form and pruning, they softly mound, cascade, or grow upright in the border. Hardy chrysanthemums (also called garden mums) offer seasonal decor for porches and autumnal displays. We often purchase them at garden centers as rounded, potted specimens fully budded for seasonal color. 

When transplanted in the right conditions, these grow year-round in containers or in the ground. They provide lasting interest as thriving outdoor selections and showy cut flowers. Let’s dig into how you can propagate chrysanthemums through cuttings, seeds, or division.

Propagation Guidelines

Chrysanthemums are vigorous clumping perennials hardy in USDA zones 3-9. Hardy mums are versatile in garden beds and containers, provided they have full sun and rich, well-draining soils. Propagation is straightforward when starting a new collection or expanding an existing colony.

Cuttings are the primary way to propagate these easy growers and produce the most new plants. Mother plants also benefit from division, which becomes a simple way to create a larger crop. Some selections grow from seed.

Morning sun exposure is optimal for growing mums as part of their daily sun requirements. They perform best in fertile, loamy, or sandy soils with good drainage. Good air circulation is essential for preventing fungal diseases. 

Prepare your transplant area by checking soil quality and adding compost or broken-down organic matter to increase richness and aeration. Lightly turn the soil to loosen it and promote root development for seedlings.

Cuttings

Softwood cuttings are a viable way to create many plants relatively quickly. Take cuttings from pliable stems in spring and early summer when shoots reach eight to ten inches tall.

It’s best to clip in the morning when stems are turgid and holding water before the day’s heat. Use clean, sharp pruners, snips, or a knife to make precise cuts on stems.

Cuttings taken in spring will flower in late summer. The whole process takes one to two months for sturdy seedlings. Cuttings develop roots in three to four weeks for transplanting. New plants will be tender; harden them off outside in a protected area for a week or two before installing them in their new garden location.

How To Take Cuttings

Taking cuttings is simple as long as you have sharp, sanitary tools and quality potting medium.

1. Cut a three-to-four-inch piece of healthy stem just below a leaf node. The best options are non-flowering, non-woody stems.
2. Remove leaves from the bottom half of the cutting, keeping the upper sets intact. Cut large leaves in half to limit transpiration.
3. Keep cuttings moist until ready to pot.
4. As an optional step to promote growth, moisten the cutting and dip the base of the stem in the rooting hormone. Tap off any excess powder if you’re using rooting powder.
5. Stick the cutting one inch deep into a tray or cell with sterile potting medium, moist and well-draining. Vermiculite, perlite, and sand make suitable mixtures.
6. Place the cuttings in a bright, warm location away from direct sunlight. To increase humidity, use a clear plastic cover or bag, making sure it doesn’t touch the cuttings. If using a cover, ensure temperatures don’t exceed 75°F (24°C) for best success.
7. Water or mist to keep the soil evenly moist, usually daily. 
8. When roots have taken hold and new growth emerges, transplant stems to a larger pot or into the garden. An indicator of roots is when the cutting resists a gentle tug.

Seeds

Propagation from seeds occurs less often in the home garden than cuttings or divisions. Hybrids won’t come true from seed, so the offspring don’t necessarily reflect the parent plant.

Hand-pollinated varieties are available through seed sources. Direct-sow them after the final frost in spring or start them indoors over the winter.

How To Sow

Use cell packs or trays and a seed-starting medium to start seeds indoors in late winter. Keep the trays at 70-75°F (21-24°C). Seeds germinate in one to three weeks and are ready for transplanting about one month after sowing. As with cuttings, allow a hardening-off period for seedlings to adjust to outdoor conditions.

For direct sowing, thin seeds after germination according to adequate spacing for the variety. Seed-propagated chrysanthemums bloom about three months after planting and have a long flowering period.

Division

Hardy mums have shallow root systems and are easily dug and transplanted. Over time, the original plant becomes less vigorous. Dividing rejuvenates growth, prevents overcrowding, and promotes flowering. It also creates new plants for years of recurrent color.

The best time to divide is in the spring as new growth emerges and when shoots reach one to three inches long. Chrysanthemums benefit from division every two to three years, and this is also a great opportunity to propagate more plants. Divide when established plants show crowded central crowns with less vigor and flowering.

Best Practices

To divide mums, dig the whole plant with a spade or digging fork. The shallow roots make it easy to lift out of the soil with little root disturbance.

Loosen roots and shake off excess soil. Snip and brush away woody stems and debris. Remove and discard any diseased parts. 

Work with the outer perimeter to begin dividing. Here, you’ll find new plants with shoots and roots that separate easily from the mother plant.

With your sharp blade or spade, separate the remaining clump into sections. Each segment should have viable stems (growth points) and roots attached. These become the new garden transplants.

Gauge the viability of the existing mother plant to determine if the central crown is healthy and productive. If so, divide it into large segments for replanting. If it is densely packed and lacking new growth, compost the old portion and rely on the newly divided plants for fast development.

For the best viability, replant the segments shortly after dividing them. With the planting area prepped and amended, tuck the divisions into loose, well-drained, organically rich soils.

Young divisions, free of crowded roots and stems, grow quickly. They’ll flower in the fall after a spring division.

Seedling Care

Mums are low-maintenance, but new transplants need consistently moist soils as roots establish in the first growing season. Plant seedlings at least 18 to 24 inches apart, depending on the variety. Allow plenty of airflow between plants.

Water the transplants thoroughly at planting. Mulch to regulate soil temperatures, retain moisture, and suppress weeds.  A few weeks after planting, apply a balanced granular fertilizer.

Flowering Tips

Pinching new growth at various phases of development creates healthy, full forms and all-over flowering. This form of light pruning creates compact, sturdy stems for uniform budding and blooming.

When stems reach eight inches tall, pinch off the light green growth tip to encourage side branching. Pinch growth tips from the side shoots for dense growth every couple of weeks. Depending on the variety’s bloom time, pinching occurs through late June before buds set. Pinching too late into the summer prevents buds from forming, resulting in fewer flowers.

Disbudding is a technique some gardeners use for display-quality floral enhancements. In large-flowering varieties, disbudding directs energy to single, large buds and blooms rather than a series of less substantial flowers. Pinch off side shoots and remove buds other than the primary central flower bud on stems.

Deadheading during the late summer and fall bloom period promotes more budding and flowering, keeping color going through frost. Cut plants down to eight inches tall in late fall to prepare for winter dormancy.

Overwintering

In lower growing zones, add extra mulch for cool-season protection. Use a light layer of mulch or soil on crowns, or add evergreen boughs to protect against ice and frost-heaving as soils freeze and thaw.

To overwinter the perennials in containers, place them in a cool, sheltered location like a garage or basement until the final frost passes in spring. Check the soil moisture level occasionally to keep roots from drying out completely.

Enjoy your crop of newly propagated chrysanthemums in the spring. With a little practice, you’ll only need to buy them when you’re ready to add new varieties to the display.