Rhubarb, a hardy perennial, is cherished for its tart, edible stalks that signal spring. Growing from short, thick rhizomes, this plant returns year after year, providing an early harvest. Winterizing rhubarb involves protective measures to ensure its survival and productivity.
Why and When to Winterize Rhubarb
Winterizing rhubarb safeguards the plant’s crown and root system from freezing temperatures. This conserves energy, promoting robust growth and higher yields in spring. Rhubarb thrives in cooler climates, requiring an annual cold period to stimulate new growth.
Winterizing typically begins after the first hard frost, once foliage dies back. Complete these steps before the ground freezes solid, allowing the plant to enter dormancy. Timing varies by climate zone, but generally occurs in late autumn.
Essential Winterizing Steps
Cleaning Up
Clear away dead or decaying foliage and stalks. Removing this debris helps prevent pests and diseases from overwintering and infecting the plant. Discarding the large, triangular leaves, which contain oxalic acid, is important, though their toxicity breaks down during decomposition if added to a compost pile.
Mulching
Apply a thick layer of organic mulch around the rhubarb crown for insulation and protection. Materials such as straw, shredded leaves, or well-rotted compost are suitable choices. This mulch layer, typically 2 to 4 inches deep, helps stabilize soil temperatures, preventing freeze-thaw cycles that can heave shallow-rooted plants. Apply mulch after the ground has cooled but before it freezes, and avoid covering the crown directly to prevent rot.
Watering
Water the rhubarb adequately before the ground freezes, especially after a dry autumn. Sufficient moisture helps prevent desiccation over winter. Deep watering allows roots to absorb enough moisture to sustain the plant through its dormant period.
Avoiding Late Fertilization
Fertilizing rhubarb in late fall is generally not recommended as it can stimulate new, tender growth vulnerable to frost damage. Instead, focus on providing nutrients in the spring or earlier in the fall, allowing the plant to harden off naturally before winter sets in. An exception might be a layer of well-rotted manure or compost applied around the plant, not directly on the crown, which can slowly release nutrients and provide some insulation without promoting late growth.
Preparing for Spring Revival
As winter transitions to spring and temperatures begin to rise, preparing your rhubarb for renewed growth is important. Gradually removing or raking back the heavy layer of winter mulch is beneficial. This allows the soil to warm more quickly, signaling to the plant that it is time to break dormancy and encouraging new shoots to emerge. Leaving too much mulch around the crown in spring can delay emergence and potentially lead to crown rot.
Once new growth is evident, a light application of balanced fertilizer or well-rotted compost can provide a boost of nutrients for the vigorous spring growth. Ensuring adequate moisture as the plant emerges from dormancy and begins to produce new stalks is also important. As the plant breaks dormancy, look for the appearance of reddish buds pushing through the soil, indicating the start of another productive season.