Chrysanthemums, commonly known as mums, are the quintessential flower of the autumn season, providing a burst of color when most other plants are fading. These vibrant blooms are popular for decorating porches and gardens, signaling the arrival of fall. To maximize the display life of these short-day plants, understanding the correct timing for purchase and placement is necessary. This guide provides instructions on when to put out mums for the longest-lasting color display.
The Optimal Time to Purchase and Place Mums
The best time to purchase mums for a long-lasting display is generally from mid-September onward, after the most intense heat of summer has passed. Mums bought too early, such as in late August, risk being stressed by high temperatures, causing flowers to fade quickly. Cooling nighttime temperatures indicate the plants will thrive and their blooms will be sustained for weeks.
The most important factor in selecting a plant is its bloom stage. Look for mums with abundant buds that are just beginning to show color, rather than those already in full flower. A plant covered in tight or “breaking” buds ensures the entire bloom cycle happens while it is in your care. Mums bought in full bloom offer immediate gratification but will only last for a couple of weeks before the flowers age and decline.
Placing mums out 4 to 6 weeks before the first anticipated hard frost is a good guideline to ensure a substantial viewing season. Early, mid, and late-season varieties are available; late-season mums are often tightly budded and provide color well into October. Choosing a plant with more buds than open flowers can extend the color show by a couple of weeks or more.
Immediate Placement and Initial Setup
Once you have purchased your mums, immediate placement and setup are important for a successful transition outdoors. Chrysanthemums thrive in bright conditions. While they need full sun for bloom setting, once purchased in bloom, they can be placed in partial shade to prolong the life of the open flowers. The ideal spot should receive at least six hours of sunlight daily.
The container must have adequate drainage holes to prevent the shallow root system from sitting in soggy soil, which leads to root rot. If placing the plastic nursery pot inside a decorative container, ensure the inner pot is slightly elevated to allow water to flow freely. Upon placement, thoroughly water the mum until it drains from the bottom, as the root ball is often compacted and dry from the nursery.
If the plant came from a highly protected greenhouse, briefly “hardening off” the mum helps it acclimate to harsher outdoor conditions. Place it in a partially shaded outdoor area for a few days. This process prevents shock from sudden changes in temperature, wind, or light intensity. After this adjustment, move the plant to its final, brightly lit display location.
Ongoing Care to Extend the Display Season
To maintain the vibrant look of your mums, consistent attention to moisture levels is necessary throughout the display season. Mums have a dense, shallow root system that causes them to dry out quickly, especially in containers. Check the soil daily, and water deeply whenever the top inch of soil feels dry to the touch, ensuring water drains out the bottom of the pot.
Regularly removing spent or faded flowers, known as deadheading, encourages the plant to put energy into opening new buds rather than producing seeds. Pinching off the entire dead flower head and the small stem beneath it keeps the plant tidy and promotes new blooms. This practice can significantly extend the overall bloom duration.
Fertilization is generally unnecessary for seasonal mums, as they were heavily fed at the nursery to support their current flush of blooms. Adding a dilute liquid fertilizer is only beneficial if you anticipate a display period extending beyond four to six weeks. If an unexpected light frost is forecasted, temporarily moving container mums to a sheltered area, such as a covered porch or garage, protects the open flowers and buds from damage.
Seasonal Use vs. Permanent Planting
Most chrysanthemums sold in the fall are treated as seasonal annuals, meant to provide a temporary burst of color before being discarded after a hard frost. However, many garden mums are technically perennial varieties capable of surviving winter in certain climates. The challenge with planting fall-purchased mums for perennial use is timing, as their root systems are not well-established.
For the best chance of overwintering success, a mum should be planted at least six weeks before the first hard, killing frost. This window allows the shallow roots to grow and anchor the plant firmly before the ground freezes. Gardeners in milder climates may succeed with fall planting. However, those in colder zones should plant hardy mum varieties in the spring to give them an entire growing season to establish a robust root system.
Planting a heavily budded or fully blooming mum in late fall significantly reduces its chances of surviving winter because the plant focuses energy on flowers instead of root growth. If attempting to overwinter a fall-planted mum, leave the dead foliage in place. Apply a thick layer of insulating mulch once the ground is frozen to protect the crown from temperature fluctuations and frost heave.