Why Are My Blueberries So Small?

Blueberry bushes are perennial, woody plants offering both ornamental foliage and edible fruit, making them increasingly popular in home landscapes, according to the University of Minnesota Extension. They can be challenging to grow, however. When your plant produces small blueberries, it may be due to one or more reasons, including variety, maturity and care.

Native to the United States, blueberries traditionally grow commercially in cool zones such as the Pacific Northwest and north-central regions. Thanks to new cultivars, blueberries now grow in temperate climates from Florida to California. Blueberry varieties range from large-fruit blueberries such as "Chandler" to small-fruit such as "Rubel." Size is no indicator of flavor, as small berries often have rich taste suited to baking pies. Your blueberries may be small because the bush is a small-fruit bush. Consider planting a companion blueberry of a different variety as the cross-pollination frequently results in larger fruit on your original bush.

Blueberry bushes mature slowly. A blueberry bush begins fruiting at one or two years, but the bush is not fully productive until it is six to eight years old. Young bushes yield small fruit. Rub off the flowers if your bush is young; flowers take nutrition away from the growing bush. While the plant is young, the vegetative growth helps the bush develop strong canes and roots but flowering and fruit production hinder growth, resulting in a small bush and sparse fruit.

Blueberries produce fruit on new and vigorous wood. As the bush matures at five years, look for old and weak canes. Prune these off at ground level in late winter or early spring. A rule of thumb is that the thicker the wood, the larger the fruit. Old and weak wood yields small berries. As blueberries fruit on one-year canes, keep the strongest mature canes and two or three new canes that will yield next year’s crop.

Flowers mature into blueberries, but too many flowers on mature bushes result in small berries. Remove at least half the flowers and tiny fruit so that the remaining fruit is large and juicy. Thin the flowers by rubbing them off with your fingers or gloves. Another method is pruning the flowering shrub. Often the weak and stunted twigs have the most flowers and fewest leaves. Prune these twigs and flowers near the end of flowering season. This reduces strain on the canes and encourages fruit production, larger fruit and healthier plants.

Blueberry plants are thirsty. They have shallow roots and need a minimum of 1 to 2 inches water per week in spring and summer. Use a soaker hose or drip irrigation so that water does not splash on the foliage and encourage disease. Water deprivation results in small berries and sparse production.