Dahlias are celebrated in gardens worldwide for their spectacular blooms, which appear in a dazzling array of colors and forms. When gardeners work around the plant’s structure or prepare to cut the flowers, a common question arises regarding potential hazards. The definitive answer is that the stems of a dahlia do not possess thorns, lacking the sharp, protective structures seen on many other plants.
The Botanical Distinction
The fear of sharp projections often stems from a misunderstanding of botanical terminology. In the plant world, pointed, rigid structures are classified into three distinct categories: thorns, spines, and prickles. A true thorn is a modified stem containing vascular tissue, originating from an axillary bud, such as those found on a citrus tree. Spines are structurally modified leaves, commonly seen on cacti where the leaf surface has been adapted for defense. Prickles are sharp outgrowths of the plant’s epidermis, lacking vascular tissue, which makes them easy to detach, like the sharp points on a rose stem. Dahlia stems are often described as fistulous, meaning they are hollow, and the exterior texture is typically smooth or only slightly rough.
Why the Confusion Exists
The widespread confusion about dahlias having thorns likely originates from their frequent association with other spiny garden plants. Roses, which possess numerous prickles, are often grown in the same mixed borders as dahlias. Another common garden presence is the thistle, whose foliage has sharp projections, leading many people to adopt caution when working around large, leafy blooms. Gardeners may also confuse the rigid, sometimes rough texture of a mature dahlia stem with a defensive structure. The stems of tall dahlia varieties become thick and can feel woody near the base as the season progresses, prompting an automatic assumption of sharpness.
Safe Handling Practices
Since dahlias are not equipped with thorns, the main concern when handling them shifts from defense to support and fragility. The hollow, herbaceous nature of the stem makes it susceptible to snapping, especially in tall varieties or those with heavy “dinner plate” blooms.
Stem Support and Cutting
For this reason, staking is commonly practiced, where sturdy supports are placed early in the season to prevent the stems from bending or breaking under their own weight or from wind. When cutting dahlia flowers for arrangements, it is best to use a sharp, clean tool to make a precise cut just above a node, which is the point where a leaf or bud emerges. This clean cut minimizes damage to the remaining plant and promotes future branching.
Tuber Handling
Care is also necessary when handling the fragile tubers during the autumn digging and winter storage process. The neck connecting the tuber to the crown is delicate and must remain intact to ensure future growth. The fragility of the tubers is a primary consideration during seasonal maintenance.