The ‘Mexican Star’ dahlia is a striking addition to any garden, known for its distinctive appearance. This cultivar combines dark foliage with vibrant, star-shaped flowers, creating a dramatic contrast. Its unique visual appeal makes it a popular choice for mixed borders or as a focal point, providing an engaging display throughout the growing season.
Understanding Dahlia Mexican Star
The ‘Mexican Star’ dahlia distinguishes itself with unique characteristics. Its foliage is notably dark, often bronze, mahogany, or near-black, providing a dramatic backdrop for its blossoms. This deep coloration enhances the vibrancy of the flowers.
The flowers are typically vivid orange-red or scarlet, sometimes dark chocolate-red, with a single-petaled, open-faced form. These star-shaped blooms often have a bright yellow central disc, creating a striking contrast with the dark petals. Flowers are relatively small, around 6-7 cm (2.5-3 inches) in diameter, and some sources note a light, almost chocolate-like fragrance. This dahlia typically grows to a height of about 70 cm to 1.2 meters (2.3 to 4 feet) with a spread of 0.5 to 0.8 meters (1.6 to 2.6 feet), exhibiting an upright growth habit. It is classified as a single-flowered dahlia.
Planting and Growing Conditions
Successful establishment of ‘Dahlia Mexican Star’ requires careful consideration of its planting environment. Full sun exposure is paramount for abundant blooms, requiring at least six to eight hours of direct sunlight daily. A sheltered location also protects plants from strong winds.
Ideal soil for ‘Mexican Star’ dahlias is well-draining, fertile, and rich in organic matter. While it tolerates various soil types, proper drainage is crucial to prevent tuber rot. A slightly acidic to neutral pH range is preferred. Amending heavy clay soils with compost or other organic materials improves drainage and fertility.
Planting should occur after the last spring frost, when the soil has warmed sufficiently. This typically falls around mid-May in many regions, or when night temperatures consistently stay above 10°C (50°F). Tubers can also be started indoors in pots in late winter to early spring for an earlier start.
When planting tubers directly, place them horizontally with the “eye” facing upwards, about 10-12 cm (4-5 inches) deep. Space tubers about 50-60 cm (20-24 inches) apart for proper air circulation and growth. After planting, provide a thorough initial watering to settle the soil. Avoid overwatering at this early stage, as tubers are susceptible to rot.
Ongoing Care and Maintenance
Consistent watering is important for ‘Dahlia Mexican Star’, especially during dry periods, to support vigorous growth and large leaves. While they need ample moisture, ensure good drainage to prevent water accumulation around the roots, preventing rot. Less water is required in early growth, but as the plant matures, its water needs increase, particularly on sunny days.
Fertilizing supports continuous blooming and overall plant health. During early growth, a balanced liquid fertilizer or one with higher nitrogen encourages foliage development. Once flower buds form, shift to a fertilizer with higher phosphorus and potassium, applied every 7-10 days, to support flower production. Cease fertilization when flower buds show color or during high temperatures.
Deadheading, the removal of spent blooms, encourages the plant to produce more flowers throughout the season. Removing faded flowers redirects energy from seed production to new buds. Snip off the entire flower stem down to a leaf joint or side shoot.
As ‘Dahlia Mexican Star’ can reach 1.2 meters (4 feet), providing support may be necessary to prevent stems from bending or breaking. Staking with canes or using plant supports helps maintain an upright habit. Pinching back young plants, by removing the central growing tip when 20-30 cm (8-12 inches) tall, encourages bushier growth and more lateral branching, resulting in more flowers.
Common Challenges and Solutions
Gardeners growing ‘Dahlia Mexican Star’ may encounter various issues, many of which can be managed with proactive measures. Pests like aphids, slugs, earwigs, thrips, and spider mites can affect dahlias.
Common Pests and Solutions
Aphids: These small sap-sucking insects cause distorted leaves and can be controlled with strong jets of water or insecticidal soap.
Slugs and Snails: Particularly damaging to young plants, they can be deterred by keeping the soil surface dry and removing them manually.
Earwigs: They feed on leaves and flower buds; maintaining a tidy area around plants helps to reduce their presence.
Thrips and Spider Mites: Thriving in hot, dry conditions, they cause discoloration and distortion; consistent watering and insecticidal soaps can help manage them.
Diseases
Dahlias are susceptible to certain diseases, especially in conditions of high temperature and humidity. Powdery mildew appears as a white, powdery coating on leaves and stems, while botrytis (grey mold) causes dark, fuzzy mold on buds and stems. Ensuring good air circulation by proper spacing and pruning, along with avoiding overwatering, can help prevent these fungal issues. Promptly removing infected plant parts is also important to prevent spread.
Lack of Blooms
A lack of blooms can be frustrating, often stemming from insufficient light, improper feeding, or plant stress. Ensure the dahlia receives full sun exposure and adjust fertilization practices to provide adequate phosphorus and potassium during the blooming phase. Stress from drought or excessive heat can also inhibit flowering, so consistent watering is important.
Leggy Growth
Leggy growth, where stems become long and stretched with sparse foliage, typically indicates insufficient light. Moving potted plants to a sunnier location or ensuring garden plants are not overshadowed by other vegetation can remedy this. Pinching back the growing tips of young plants also encourages a more compact, bushier form rather than tall, spindly growth.
Overwintering Your Dahlias
For gardeners in colder climates where the ground freezes, overwintering ‘Dahlia Mexican Star’ tubers is necessary to ensure their return the following year. The ideal time to dig up tubers is after the first hard frost has blackened the foliage, signaling the plant’s dormancy. Allowing the tubers to remain in the ground for one to two weeks after frost can help their skin toughen for storage.
To dig, carefully loosen the soil around the plant using a garden fork, starting at least 30 cm (12 inches) away from the central stem to avoid damaging the tubers. Gently lift the entire clump from the soil, brushing off excess dirt. If washing tubers, ensure they dry completely before storage to prevent rot. Allow the tubers to cure in a cool, dry, and well-ventilated area for several days to a week. Any damaged or rotten sections should be removed, and the tubers can be divided at this stage if desired, ensuring each section has at least one “eye.”
Once cured, store the tubers in a cool, dark, and frost-free location where temperatures remain consistently between 4°C and 10°C (40°F and 50°F). Good air circulation is important, so avoid sealed containers. Suitable storage mediums include peat moss, vermiculite, wood shavings, or coarse sand, which help maintain a stable moisture level and prevent drying out or rot. Place the tubers in crates or paper bags, surrounded by the chosen medium, ensuring they do not touch each other if possible. Periodically check the stored tubers throughout the winter for any signs of mold, shriveling, or rot, discarding any affected ones to prevent spread.