A rhubarb forcer is a traditional gardening implement used as a specialized covering to encourage an early harvest of the plant’s stalks. This technique, known as forcing, tricks the rhubarb crown into breaking its winter dormancy weeks ahead of its natural schedule. The goal is to produce stalks that are sweeter, more tender, and less acidic than those grown in the full light of the spring and summer seasons.
Anatomy and Mechanism of the Forcer
The rhubarb forcer is typically a large, bell-shaped pot, traditionally crafted from terracotta clay, though modern versions are also made from plastic or metal. Its design features a wide base to cover the entire plant crown and a tall, conical shape for vertical growing space. A small lid or aperture at the top allows for periodic checking of the growth without removing the entire covering.
The mechanism relies on two primary biological principles: etiolation and thermal insulation. By completely blocking out light, the forcer prevents photosynthesis and the production of chlorophyll, which normally gives the stalks their green color and tart flavor. The absence of light causes the plant to stretch upward rapidly in an attempt to find a light source, a phenomenon called etiolation, resulting in long, pale, and delicate stems. The second function is to trap heat radiating from the ground, creating a warm microclimate around the dormant crown. This warmth simulates an earlier spring, prompting the plant to begin its growth cycle prematurely. Some gardeners enhance this effect by insulating the outside of the forcer with materials like straw or well-rotted manure.
Step-by-Step Guide to Forcing Rhubarb
The process of forcing begins in late winter, typically from December through February, after the rhubarb crown has experienced sufficient cold to break its dormancy. Select a mature, healthy crown that is at least two years old, as younger plants lack the energy reserves needed for forced growth. Forcing the same crown every year is not recommended because it depletes the plant’s resources, so gardeners often alternate between two or three plants.
Before placing the forcer, clear away any dead leaves or debris from around the base of the selected plant. Applying a generous mulch of well-rotted compost or manure around the crown can boost nutrient levels and provide extra warmth. The forcer is then carefully placed over the crown, ensuring that no light can penetrate, and the small lid at the top is secured.
The forcing period usually lasts between four and eight weeks, depending on the ambient temperature and rhubarb variety. The small top lid allows for a quick check of the emerging stalks without disturbing the internal environment. The forced rhubarb is ready to harvest when the stalks are approximately 45 to 50 centimeters long or are just touching the top of the forcer. To harvest, gently twist and pull the stalk from the base of the crown, taking care not to damage the remaining buds.
Characteristics of Forced Rhubarb
Forced rhubarb is distinct from its outdoor-grown counterpart, primarily due to the exclusion of light. The stalks display a characteristic pale pink or crimson color, sometimes with a white or creamy-yellow hue, which is a direct result of the suppressed chlorophyll production. This color also translates into a significantly different flavor profile. By growing in the dark, the plant draws upon its stored energy reserves, resulting in stalks that are naturally sweeter and notably less acidic. The reduced acidity means that less sugar is required when the rhubarb is cooked. Furthermore, the rapid, upward growth yields a texture that is much more tender and less stringy or fibrous than sun-grown rhubarb. The main benefit of this process is the early timing, which provides a fresh harvest months before the regular outdoor rhubarb season begins.