The perennial vegetable rhubarb (Rheum rhabarbarum) is often treated like a fruit, signaling the arrival of spring with its stout, tart stalks. Rhubarb returns year after year from the same root system. Identifying this initial growth accurately requires knowing the specific visual cues that differentiate it from other garden sprouts.
The Emergence Timeline
Rhubarb is a cold-weather plant that requires a period of dormancy, with winter temperatures dropping below 40°F, to stimulate new spring growth. The large, leafy tops die back after the first heavy freeze in the fall. The initial push of growth begins as the soil warms slightly in late winter or early spring. The plant breaks dormancy and starts to grow when spring temperatures rise above 40°F. Gardeners can expect to see activity when the soil temperature reaches a minimum of 50°F. This means rhubarb is one of the first vegetables to show life, often appearing long before the threat of frost has completely passed.
Identifying the Initial Sprout
The first sign of rhubarb is the swelling of the crown buds just beneath the soil surface. These buds are the plant’s growing points, located on the large, fleshy root structure. As the buds begin to swell, they appear as tight, compact, and knobby structures. These emerging buds often have a distinct reddish-brown or pinkish tint, a color that is transferred to the earliest parts of the emerging stalks. They push through the soil as a cluster of tightly wrapped growth, resembling a small, bumpy fist emerging from the ground. This initial growth is often protected by papery, sheath-like coverings before the true leaves and petioles elongate.
Visual Characteristics of Emerging Stalks and Leaves
Once the crown bud has broken the surface, the structure begins to elongate into the stalks and the tightly furled leaves. The stalks are thick and fleshy, often displaying a vibrant color gradient ranging from deep ruby red to pink, or sometimes remaining entirely green depending on the specific cultivar. The leaves emerge tightly folded, resembling a closed umbrella or a compact, pleated ball. As the stalks lengthen, the leaves begin to unfurl, transitioning from a dense reddish-purple color to a bright, rich green. The texture of the emerging leaf is noticeably crinkled or lobed, giving it a distinct appearance before it fully expands into its mature, heart-shaped form. The stalks themselves have a smooth surface and a solid cross-section, differentiating them from other plants that may look similar.
Avoiding Misidentification
Identifying emerging rhubarb correctly is important because the large, mature leaves are poisonous if ingested. The most common plants mistaken for emerging rhubarb are burdock (Arctium) and curly dock (Rumex crispus), both of which can have large, basal leaves. A significant difference in the earliest stages is the texture of the leaf surface. Rhubarb leaves are smooth, even when crinkled in their emerging stage. Conversely, the leaves of common burdock are often described as having a woolly or hairy texture, particularly on the underside. Furthermore, the mature stems of burdock are hollow, whereas the stalks of rhubarb are solid. Observing the distinct reddish hue of the rhubarb crown and the smoothness of the emerging leaf is key.