The Roots & Flowers of Dahlias

Flowers

• Read notes that dahlias offer gardeners one of the largest selection of flower size, shape and color, and they can be seen in bloom from early summer through the first frost. Flowers appear as solid, striped or patterned shades of red, yellow, orange, pink, purple and white, as well as other colors, except blue. Dahlia flowers range in size from half-inch compact blossoms to plate-size blooms that are nearly a foot across in diameter.

Flower Classificiation

• The North Carolina Cooperative Extension Service notes that dahlias are classified by their flower shape and petal arrangement. Single-flowering dahlias are small and exhibit one ring of evenly-spaced petals and include anemone, collarette and orchid-flowering varieties. Double-flowering dahlias, which include cactus, semi-cactus and incurved cactus varieties, are taller, have larger flowers that exhibit multiple rows of petals and are further classified according to the blossom shape and size. Formal decorative dahlia flowers feature broad, regularly-arranged rounded or pointed petals that curl towards the stem while informal decorative dahlias feature long, irregularly arranged and sometimes twisted petals. Ball dahlias, of which the pompon varieties are miniature versions, feature a ball or somewhat flattened shape, with quilled petals that are rounded blunt.

Roots

• Dahlia roots are fleshy, tuberous specimens that slightly resemble sweet potatoes. As Read notes, the tuberous root is the storage organ of the dahlia, and they can be left in the ground to go dormant and over-winter, if cut back properly, to produce new blooms next summer. The tuberous root appears as a clump when allowed to grow freely, and dahlias require heavy feedings of potash for good rood development. Over-watering, however, can cause severe damage to dahlia roots as can exposure to direct sunlight and cold temperatures.

Root Division

• Read states that the proper division of dahlia roots is a common method for propagation. Dahlias are hybrids, and growing flowers from root divisions is the best way to ensure the consistency of your strain. Divide dahlia tubers after they have sprouted live buds, known as "eyes," but before any new growth grows more than an inch, as suggested by the Oregon State University Extension Service. Properly divided dahlia roots will have at least one live bud or sprout, as the separation will occur at the crown, which is located where the old stalk joins the root and where new buds grow. Avoid spearing the roots when you collect them from the ground for division, and be aware of any new shoots as they can break off easily.