Rhubarb is a hardy perennial valued for its tart, edible stalks that emerge reliably each spring. Successfully establishing this plant requires understanding your local climate, particularly the USDA Plant Hardiness Zone. Zone 7 features mild winters, with minimum temperatures ranging from 0°F to 10°F, and a long, warm growing season. Knowing this zone dictates the precise planting window necessary for the plant’s long-term health and productivity.
Specific Planting Windows for Zone 7
The most opportune moment to plant rhubarb crowns or bare roots in Zone 7 is the very beginning of spring. This window typically opens in late February and extends through early April, starting as soon as the soil is thawed and workable after the last significant frost. Planting during this cool period allows the dormant crown to develop a robust root system before the onset of summer stress.
Rhubarb thrives when its roots establish in the cool, moist soil conditions prevalent in Zone 7 during early spring. If planting is delayed until late spring or early summer, the plant will struggle to manage intense heat and may fail to establish a strong foundation. Early planting maximizes the time the plant has to acclimate.
Fall planting is a secondary option, usually from late September through October. This timing allows roots to settle before the ground freezes, ensuring an immediate spring start. However, fall planting carries a higher risk of heaving or crown damage if an unusually harsh or early cold snap occurs before the roots are fully anchored.
Site Selection and Soil Preparation
Selecting the proper site is necessary for rhubarb’s longevity. The plant requires a location that receives full sun, meaning a minimum of six hours of direct sunlight daily to ensure vigorous stalk production. The site must also offer excellent drainage, as rhubarb’s fleshy roots are highly susceptible to rot when exposed to standing water.
Rhubarb is a heavy feeder that performs best in deeply worked soil rich in organic matter. Amending the planting area with well-aged compost or manure several weeks prior to planting provides necessary nutrients and improves soil structure. This preparation ensures the roots can spread easily and access moisture.
The preferred soil pH range is slightly acidic to neutral, between 6.0 and 6.8. Testing the soil beforehand allows for adjustments, such as adding lime or sulfur, optimizing the environment for nutrient uptake. A well-prepared bed supports the plant for years, as rhubarb can remain productive for a decade or more.
Planting Rhubarb Crowns
The planting process requires careful attention to spacing and depth to accommodate the plant’s mature size. Rhubarb plants spread significantly and should be spaced three to four feet apart to allow for adequate air circulation and nutrient access. Dig a large hole that is deeper and wider than the crown or bare root mass.
When placing the crown into the prepared hole, ensure the roots are spread out naturally. The plant’s crown—where the buds are located—should be positioned so the buds rest just below the soil surface, typically one to two inches deep. Planting too deeply can lead to crown rot, while planting too shallowly exposes the roots to drying conditions.
Gently backfill the hole with the amended soil, lightly firming it around the crown to eliminate air pockets. The area should then be thoroughly watered to settle the soil around the newly planted crown. This initial watering ensures immediate root-to-soil contact and hydration.
Immediate Care and First Harvest
After planting, consistent moisture is necessary, especially during the first growing season and any prolonged dry spells in Zone 7. The soil should be kept evenly moist but never saturated to encourage strong root development. A light side dressing of balanced fertilizer or fresh compost can be applied once the plant shows signs of active growth.
The most important rule for first-year care is to resist harvesting any stalks. Allowing the foliage to grow completely undisturbed directs all photosynthetic energy back into the root system and crown. This energy storage is necessary for the long-term vigor and survival of the perennial plant.
Adhering to the non-harvest rule in the initial year ensures a more robust yield in subsequent seasons. A light harvest can usually commence in the second year, and a full, sustained harvest can be expected starting in the third year.