Rhubarb is a perennial whose tart, fleshy leaf stalks are used culinarily as a fruit. The annual harvest is a delight for many gardeners, marking one of the earliest crops of the growing season. Knowing the precise timing and method for harvesting is paramount for maximizing your yield and ensuring the long-term health of the plant.
Determining Seasonal Readiness
Once established, the harvest season typically begins in early spring, often in April or May, depending on the local climate and cultivar variety. The visual cue for readiness is the size of the stalk, not its color, which can range from bright red to speckled green. Stalks are ready to pick when they are plump, firm, and have reached a length of at least 10 to 15 inches.
Leave any thin or spindly stalks alone, as removing them can weaken the plant. Look for stalks with fully unfurled leaves, indicating the plant has sufficient foliage to support its growth. Harvest only the thicker, more robust stems.
Establishing the Rhubarb Plant
First Year Establishment
In the first year after planting a rhubarb crown, the plant must dedicate all its energy to developing a strong root system. During this initial period, the plant is focused on building up energy reserves in its underground crown. Harvesting any stalks in the first growing season severely weakens the young plant, resulting in stunted growth and reduced yields in future years.
Subsequent Years
It is best to wait until the second year before taking any stalks, and even then, the harvest should be light and brief. By the third year, the plant should be fully established and can be harvested normally for a full season. This initial waiting period ensures the plant has the necessary energy reserves to survive the winter and produce an abundant crop for the next 10 to 15 years.
Proper Harvesting Technique and Safety
Technique
The preferred method for harvesting is the “pull and twist” technique, rather than using a knife. Grasp the stalk firmly near the soil line, lean it slightly to the side, and then twist and pull upward in one steady motion until it separates cleanly from the crown. This method encourages the plant to regrow a new stalk in its place and avoids leaving a rotting stub behind.
Safety
Cutting the stalks leaves an open wound on the plant’s crown, which creates a potential entry point for crown rot diseases. Once the stalk is removed, immediately cut off the leaf and discard it. This step is a safety measure, as the leaves contain high concentrations of oxalic acid and are toxic if consumed.
Ending the Harvest Season
Seasonal Deadline
The harvesting season for an established plant lasts approximately 8 to 10 weeks, concluding around the end of June or early July. This deadline is set for the plant’s health, not because the stalks become poisonous. As temperatures rise in mid-summer, the plant focuses on storing energy for the next year.
Maintaining Vigor
Continuing to harvest into the summer depletes the crown’s reserves, leading to thinner stalks and a weaker plant the following spring. To maintain plant vigor, never remove more than one-third to one-half of the total stalks from a single plant at any time. Allowing the remaining foliage to photosynthesize is essential for storing the energy needed for a strong return the following season.