Kale is a resilient leafy green vegetable belonging to the species Brassica oleracea, which also includes cabbage and broccoli. The ultimate size a kale plant reaches is highly variable, generally ranging from one foot to over three feet in height when mature. This variability depends primarily on its genetic makeup and how it is managed by the gardener, rather than environmental factors like soil quality.
Standard Dimensions and Growth Structure
A fully mature, non-dwarf kale plant typically achieves a height between 1.5 and 3 feet. The lateral spread, or diameter, of the plant generally matches this vertical dimension, often reaching 1.5 to 2 feet wide.
Kale exhibits an upright growth habit, starting as a low-lying rosette of leaves before developing a central, woody stem. This stem acts as the crown, continuously sprouting new leaves upward and outward. As the plant ages, especially if outer leaves are removed, the central stalk becomes taller and more bare, resembling a miniature palm tree.
How Variety Determines Maximum Size
The genetic predisposition of the specific cultivar is the largest factor determining the plant’s final size potential. Different types of kale are bred to maximize various traits, including height and leaf shape.
Dwarf varieties, such as ‘Dwarf Blue Curled’ or ‘Vates,’ are programmed to remain compact and rarely exceed 12 to 16 inches in height. These shorter plants are ideal for container gardening or smaller spaces.
Conversely, tall varieties possess the capacity to become much larger. Cultivars like ‘Lacinato’ (Dinosaur or Tuscan kale) and ‘Winterbor’ routinely grow to 2 to 3 feet tall. If left unharvested and allowed to complete their biennial life cycle, some varieties, like ‘Redbor,’ can exceed four feet. Intermediate varieties, such as ‘Red Russian,’ commonly settle into the 24- to 36-inch range.
Managing Plant Size Through Harvesting
In a garden setting, the plant’s actual size is often controlled by the gardener, independent of its genetic maximum. Consistent harvesting, known as the “cut-and-come-again” method, directly influences the plant’s physical dimensions and shape.
By regularly removing the lower, outer leaves while leaving the terminal bud intact, the plant’s overall bulk remains smaller than its full potential. This practice encourages the plant to focus energy on producing new, tender leaves from the center.
A frequently harvested plant maintains a manageable, compact form, while one left to grow without intervention becomes sprawling and bushy. Allowing the plant to reach its full maximum size often results in tougher, more bitter leaves, making size management a practical step for maximizing tenderness.