By Mary Concklin, Visiting Associate Extension Educator – Fruit Production & IPM
I have heard the question many times, when is the best time to prune blueberries – fall, winter or spring? To answer that question let’s take a look at what is going on with the plant at these different times. I am not saying let’s take a look at your work schedule because as a commercial grower taking care of your plants when it is best for them is the key to optimum production and profits.
Fall, after harvest is completed or other farm activities have wound down may be convenient for you but this is the time of year the plant is making carbohydrates (as I write this we have not had a hard freeze and leaves are still functioning on the bushes) and sending them to the roots and crown for winter storage. Carbohydrates are needed next season to kick start plant growth. Without an adequate amount of stored carbohydrates plant growth may be reduced over the long term. This may also set your bushes up for winter injury if/when we have a real winter.
Winter, after the first of the year, is a good time to see fruit buds and to assess crop load. This is especially important where detail pruning is needed. However, injury to canes from the cold and winds cannot be assessed at that time because the winter season has not been concluded.
Late winter – early spring is the ideal time to prune blueberries. It is easy to see the flower buds, assess any winter injury and adjust pruning practices to compensate. Carbohydrates are stored and ready to for the new season. Winter is over and chances of additional weather related injury are minimal. (Other than 2012 when we jumped from fall to spring and sustained some bud damage from frosts.)
A few pruning reminders:
- Prune annually to constantly renew fruiting canes. As canes age, berry production and size drops. Maintaining a six to seven year age range in canes in a single bush is important for continuous production.
- Remove the oldest 2-3 canes. It is fairly easy to tell which ones they are – they age like we do – bark begins to peel off, canes are greyer in color, oldest canes are the fatter ones.
- Prune out canes to the GROUND. New canes will arise from the crown. Allowing new shoots to be produced on old canes is not renewing the cane. It is still an old cane.
- Remove dead, scale covered and diseased canes.
- Select 2-3 of the newest canes and remove the rest of this year’s new canes. Varieties differ in the number of canes they produce each year. You may only have a single new cane or you may have 10-12 to choose from.
- Keep the center of the bush fairly open to increase sunlight penetration for increased flower bud formation, increased berry size and to reduce potential disease and insect problems.
- Detail pruning consists of the removal of dead or injured wood at the tips of canes and the removal of thin twiggy crowded growth on canes. Thin twiggy growth will produce small berries at best while sapping energy from the bush. However, with annual cane renewal pruning, detail pruning will be minimal.
Annual balanced pruning is key to continuously producing large high quality berries.
Before pruning After pruning
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