What to do now
Mildest step first.
- Wait until late winter or early spring; skip fall pruning, which can push growth that winter kills.
- Cut out dead, broken, and low branches that will sag onto the ground under fruit.
- On bushes older than about 5 years, remove the one or two oldest, thickest canes at ground level.
- Thin weak, twiggy growth and crowded canes in the center so light reaches the middle.
Not sure this is it? Check other blueberry problems
When to prune
Prune highbush blueberries while they're dormant, in late winter or early spring before the buds break. Penn State recommends near the end of the dormant season, usually March; in Iowa, Iowa State suggests late March or early April. Pruning late lets you see winter damage and tell flower buds from leaf buds. Penn State advises against fall pruning, which can stimulate new shoots that are then killed by winter cold. Blueberries flower on wood that grew the previous summer, so the fat, round buds near the tips of last year's shoots are flower buds, each holding several flowers. The small, pointed buds lower down are leaf buds.
Young bushes
Young plants need little cutting. The goal for the first couple of years is a strong root system and framework, not fruit. University of Vermont Extension suggests removing all flower buds in the first and second years by rubbing them off or cutting off the shoot tips; Penn State says to remove them at least in the first season. Beyond that, take out only dead, broken or diseased wood until the bush is about 3 years old.
Mature bushes: remove old canes
A blueberry bush is a group of canes of different ages. Canes are most productive in their middle years; Iowa State notes that yield and fruit quality decline once canes reach 5 or 6 years old. Each year on a mature bush, remove the one or two oldest canes, cutting them as close to the ground as you can. Vermont suggests removing canes before they reach about 1 inch thick at the base if you don't know their age; old canes often have gray, flaking bark and lichen. Up to about a fifth of the canes can come out each year without losing yield, and new canes from the base will replace them. Penn State suggests a mature bush keep about 10 to 15 canes of mixed ages.
Thinning the rest
After the old canes, what remains. Remove low branches that will droop onto the ground when loaded with fruit, short twiggy growth, branches crossing or rubbing, and some canes from the crowded center so light and air reach the middle. On upright varieties, open up the center; on spreading ones, remove the lowest, outward-leaning growth. If a shoot is packed with flower buds, cutting it back to leave only a few can give you larger berries.
Neglected bushes and other types
A bush left unpruned for years usually turns into a thicket of old, unproductive canes with small berries at the top. Penn State suggests renewing it over two years: cut half of the old canes to the ground one winter and the rest the next, so the bush keeps fruiting while new canes grow in. Half-high varieties grown in cold areas need only light pruning, and rabbiteye blueberries in the South generally need less detailed thinning than highbush; your local extension office can suggest timing for your area.
Growing it again? When to plant blueberry for your ZIP code
- How do I prune raspberries?It depends on the type. Summer-bearing raspberries fruit on second-year canes: cut those canes to the ground after they fruit, and thin the rest in late winter. Fall-bearing (everbearing) raspberries fruit on new canes: the simplest approach is to cut every cane to the ground in late winter.
- Why are my blueberry leaves turning red or yellow?Red leaves late in the season are normal fall color. Yellow leaves with green veins usually mean the soil pH is too high. Red or yellow leaves mid-season can also come from drought, cold, or low nutrients. Test the soil.
- My soil pH is too high (alkaline) — what can I do about it?Sulfur is the standard amendment for lowering soil pH, but it works slowly — it often takes several months to a year for meaningful change, so mix it into warm, moist soil as far ahead of planting as you can, and retest before adding more rather than going by symptoms alone.