Rhubarb is a hardy perennial plant valued for its edible, tart leaf stalks, which are frequently used in cooking. The rhubarb crown is the central, subterranean structure from which all growth originates, making it the reproductive and storage powerhouse of the plant. Understanding the nature of this crown is necessary for successfully establishing a productive rhubarb patch.
Anatomy and Biological Function of the Crown
The rhubarb crown is a thickened, short, underground stem base. Its primary function is to act as a storage organ, accumulating starches and sugars produced by the leaves during the growing season. This stored energy allows the plant to survive winter dormancy and fuels the growth of new stalks the following spring.
Visible on the crown are dormant growth points, referred to as “eyes” or buds. These eyes break dormancy when soil temperatures rise, producing the large leaves and harvestable leaf stalks. A network of fibrous feeder roots extends downward from the crown, anchoring the plant and absorbing water and nutrients.
Sourcing and Selecting Healthy Rhubarb Crowns
Gardeners typically acquire new rhubarb plants as bare-root crowns from nurseries or by dividing established plants. Inspect the crown carefully before planting. A healthy crown should be firm and plump, indicating good moisture and energy storage.
Avoid crowns showing soft, squishy areas, visible mold, or discoloration, as these indicate rot or disease. Look for the presence of at least one to three visible, healthy “eyes” or buds. Bare-root crowns should be planted quickly after purchase, but they can be temporarily stored in a cool, dark place with roots wrapped in slightly damp material to prevent drying out.
Step-by-Step Planting Guide
Rhubarb crowns should be planted in early spring when the soil is workable or in the fall after the foliage has died back. Choose the planting site carefully, as rhubarb is a long-lived perennial. Select a location that receives full sun and has consistently well-drained soil, as the crowns are susceptible to rotting in waterlogged conditions.
Before planting, prepare the area by incorporating a generous amount of organic matter, such as aged manure or compost. Dig a hole large enough to accommodate the root system, placing the crown with the buds facing upward. The proper planting depth is crucial: the top of the crown should be covered with no more than one to two inches of soil.
After setting the crown, gently firm the soil and water thoroughly to eliminate air pockets. Crowns should be spaced at least three to four feet apart to allow the large leaves to develop. Planting too deeply can delay the plant’s emergence and establishment.
Long-Term Care and Harvesting
Immediately after planting, young rhubarb crowns require consistent moisture; water them regularly during dry spells throughout the first growing season. The most important rule for the first year is to resist harvesting any stalks, known as the “First-Year Rule.” Allowing the plant to grow its full foliage enables the crown to photosynthesize maximally, building the substantial root system and energy reserves necessary for long-term health and future production.
In subsequent years, apply a fresh layer of organic mulch, such as compost or well-rotted manure, around the crown each spring. This mulching helps suppress weeds, conserves soil moisture, and provides nutrients, but avoid covering the crown itself to prevent rot.
Established plants can be harvested for an eight to ten-week period starting in the second or third year. Never remove more than one-third to one-half of the stalks at any one time. To maintain vigor and yield, established rhubarb crowns should be lifted, divided, and replanted every five to ten years.