How to Prune the Corylus Americana

The American hazelnut (Corylus americana), also commonly called American filbert, is a large deciduous shrub that reaches a mature size of up to 16 feet tall and 13 feet wide. Grown in U.S. Department of Agriculture plant hardiness zones 4 through 9, American hazelnuts flower in early spring with male plants producing brown flowers and females producing red flowers. Female flowers later produce edible nuts ready to harvest in midsummer. These fairly low-maintenance shrubs are commonly grown as hedges, but their root-suckering habit can result in dense thickets without regular pruning.

Chlorine bleach

Bypass pruners

Lopping shears

Disinfect bypass pruners and lopping shears in a solution of 10 percent bleach. Mix 1 part chlorine bleach with 9 parts water. Add the bleach solution to a spray bottle and keep it on hand among your garden supplies for easy and quick use.

Cut all root suckers back to the ground as soon as they sprout. Root suckers are the most common pruning problem with American hazelnut; suckers result in dense thickets and make the plant potentially invasive. These upright sprouts shoot up from the roots; they are less substantial than the main branches, but take valuable water and nutrients from the rest of the plant.

Trim long branches to control the size of the hazelnut shrub; cut back to a branch union or just above a bud or node on the branch. This type of pruning is only required if you need to maintain the size to fit in a designated spot in your garden.

Thin out up to one-third of the total main branches to open up the inside of the hazelnut shrub if it becomes too dense. Dense thickets of American hazelnut result in less sunlight and air circulation to the center of the plant. Cut the branches back to the ground or back to the branch union with the parent branch. This type of pruning, called rejuvenation pruning, thins out overcrowded branches, but also encourages new growth to replace old stems. Prune another one-third of the plant in the following fall and the remaining one-third in the third year of pruning.

Cut the entire plant back to the ground if it overwhelms the space, if plant performance suffers, or if you want to renew an old shrub. This type of pruning, called renewal pruning, encourages the plant to sprout all new stems. While rejuvenation pruning also leads to new branches over a longer period of time, this renewal pruning method is more desirable for misshapen or very old shrubs. American hazelnut shrubs recover well from this type of pruning.