Crab apples, which belong to the genus Malus, are small deciduous trees prized for their beautiful spring blossoms and colorful fall fruit. A fruit is technically classified as a crab apple if its diameter measures less than 2 inches (about 5 centimeters) at maturity. This size constraint is the primary defining characteristic of the fruit, although the trees themselves exhibit a wide range of physical dimensions and growth habits.
The Maximum Size of Crab Apple Fruit
The maximum size for a crab apple fruit is just under two inches in diameter. Within this limit, the actual size of the pome fruit can vary dramatically depending on the specific cultivar. The smallest ornamental varieties produce fruit as tiny as one-quarter inch, often described as “pea-sized”. These diminutive fruits, such as those on the ‘Sargent’ crab apple, are typically less messy because they often persist on the tree through winter or are quickly consumed by birds.
Most popular ornamental varieties produce fruits ranging from half an inch to one inch across. Cultivars bred for making jellies or cider, like ‘Dolgo’ or ‘Chestnut’, often push the upper boundary of the two-inch limit.
How Large Do Crab Apple Trees Grow?
Crab apple trees exhibit a significant range in size and form, often categorized as small to medium-sized trees. The height of a mature crab apple can be as short as 6 feet or can reach up to 35 feet, depending on the variety and growing conditions. Most common ornamental selections reach a moderate height between 15 and 25 feet tall.
The width, or canopy spread, is also highly variable and often matches the height, creating a rounded shape. However, some cultivars are bred for specific growth habits, such as the dwarf ‘Sargentii’ which is wider than it is tall, or columnar varieties like ‘Adirondack’ which remain narrow. The ultimate size is also heavily influenced by the rootstock used, which controls the overall vigor and growth rate of the grafted tree.
Key Factors Determining Size Variation
The variation in both fruit and tree size is primarily determined by two interacting factors: genetics and environment. The specific cultivar’s genetic programming dictates the tree’s maximum potential size and shape. For example, the ‘Robinson’ cultivar reaches 25 feet tall and wide, while the ‘Tina’ variety remains a compact shrub of about 5 to 6 feet.
Environmental conditions, such as sunlight, soil quality, and water availability, influence how close a tree gets to its genetic potential. Crab apples require full sun exposure to achieve their densest canopy and most abundant fruit set. Trees planted in poor, compacted soil or those experiencing water stress will have stunted growth and produce smaller fruit than their counterparts in loamy, well-drained soil. Furthermore, human intervention through pruning practices can actively reduce or shape the tree’s mature size, preventing it from reaching its natural height and spread.