The Dahlia ‘Cancun’ is a vibrant cultivar known for its striking, fully double blooms that feature a deep burgundy or plum-purple color dramatically tipped with white. This compact dahlia variety, often grouped in the Dalina or Maxi series, typically reaches a mature height of only 15 to 18 inches, making it an ideal choice for containers or the front of a garden border. Unlike towering dinnerplate varieties, ‘Cancun’ provides a consistent, prolific display of smaller, showier flowers. These flowers bloom continuously from late spring until the first hard frost.
Site Selection and Initial Planting
Successful cultivation of the ‘Cancun’ dahlia requires a location that receives a minimum of six to eight hours of direct sunlight daily. This sun exposure is necessary for the plant to generate the energy required for intense flowering. The planting site must also offer excellent drainage, as dahlias are highly susceptible to tuber rot in overly saturated soil.
Amend heavy clay soil by incorporating generous amounts of well-rotted compost or coarse sand to improve aeration and prevent water logging. Dahlias thrive in soil that is slightly acidic to neutral, ideally maintaining a pH level between 6.0 and 7.5 for optimal nutrient uptake. Plant the tuber only after the final frost date has passed and the soil temperature has warmed consistently to at least 60°F.
Dig a hole approximately four to six inches deep. Place the tuber horizontally with the small, visible growth bud—known as the eye—facing upward. Cover the tuber with a few inches of soil, and place a support stake next to it if heavy blooming is anticipated. Do not water the newly planted tuber; since it lacks feeder roots, moisture cannot be absorbed and the tuber is vulnerable to rot. Wait until the first green shoots emerge above the soil line, which can take several weeks, before beginning a regular watering schedule.
Sustaining Growth and Bloom Production
Once the plant is established and actively growing, its water requirements increase significantly. Aim to water established plants deeply two to three times per week, ensuring the moisture penetrates to a depth of at least eight to ten inches to encourage a strong root system. Avoid frequent, shallow sprinklings. For ‘Cancun’ dahlias grown in containers, increase watering frequency, often daily during hot weather, as pots dry out faster than garden beds.
When the plant reaches about 10 to 16 inches in height, perform a single pinch to encourage a bushier structure with multiple flowering stems. Locate the central stem and snip it just above the third or fourth pair of leaves to remove the terminal growth bud. This action redirects the plant’s energy to the lateral buds, resulting in a stronger, more branched plant that will produce many more blooms throughout the season.
Dahlias are heavy feeders and require a specific balance of nutrients to support flower production. Approximately 30 days after planting, begin a regular feeding schedule with a fertilizer low in nitrogen and higher in phosphorus and potassium. Ideal N-P-K ratios, such as 5-10-10 or 8-16-16, should be applied every three to four weeks through the summer months to promote continuous flowering.
To ensure the ‘Cancun’ cultivar continues to produce flowers, consistently remove spent blooms, a process known as deadheading. A spent flower is typically pointy and soft, while a new bud will be round and firm. Cut the entire stem of the faded flower back to the nearest set of leaves or a lateral bud. This redirects the plant’s resources away from seed production and toward developing new flower buds.
End-of-Season Tuber Storage
In regions where the ground freezes, the dahlia’s tender tubers must be lifted and stored indoors to survive the winter. The signal to begin this process is the first hard frost, which turns the above-ground foliage black. Once this happens, cut the stems back to about four to six inches above the soil line, leaving a short handle to aid in lifting.
Wait one to two weeks after the frost before digging. This allows the tuber skins to toughen and the plant’s stored starches to fully cure. Use a garden fork to gently loosen the soil in a wide circle around the plant, taking care not to pierce the delicate tuber clump. Lift the clump carefully and brush off the excess soil, or lightly rinse them with a hose if the soil is heavy clay.
The tubers must then be cured by allowing them to air-dry in a cool, dark, and protected place for two to seven days. Once dried, store them in a medium like peat moss, vermiculite, or wood shavings to maintain consistent moisture. The ideal storage environment is a dark location that maintains a cool temperature between 40 and 50°F and a high relative humidity of 75 to 85 percent to prevent shriveling.