CORVALLIS, Ore. — Moderate pruning of highbush blueberries each winter can turn a so-so harvest into a bumper crop — and improve berry quality.
Highbush blueberry, a North American native, grows 6 to 12 feet tall and is the main blueberry grown commercially. The best time to prune is during dormancy, from January to early March, said Amanda Davis, berry crops research assistant with the Oregon State University Extension Service.
“Annual, moderate pruning leads to stronger plants, higher yields and larger berries,” Davis said. “When plants aren’t pruned or are pruned too lightly, they become dense with weak, twiggy growth. They produce small fruit and don’t develop strong new wood for future crops. On the other hand, severe pruning creates lots of new wood and larger but fewer berries.”
Why consistent pruning matters
When bushes are pruned only occasionally and then pruned heavily, many young canes grow the following year. These canes age together and become unproductive at the same time. After several years, removing all unproductive canes would mean cutting back nearly the entire bush, leaving no young growth to replace the fruiting wood.
How to prune highbush blueberries
Davis recommends these steps for successful pruning:
- Remove low shoots that will touch the ground when loaded with fruit. Also remove short, soft shoots that developed late in the season from the plant base.
- Prune out canes and twigs damaged by winter injury, mechanical causes, diseases or insects. Remove unproductive canes — those with little new growth — noting that 1-year-old canes have buds but are dull in color.
- If you prune every year, remove the two oldest (and least productive) canes each winter.
- Open the plant’s center so sunlight can reach into the canopy.
- If plants tend to overbear with many small fruits, clip back some of the small shoots carrying heavy loads of flower buds. Blueberry flower buds are near the tips of last season’s growth and are large and plump compared with the small, scale-like leaf buds.
Learn more
For an overview of pruning methods and general care, consult Growing blueberries in your home garden. For more in-depth pruning instruction, an online course with videos and tips for blueberries of all ages is available through Oregon State.
