Cooperative Extension: Garden and Yard

Unfortunately, there are numerous reasons why the bushes might be showing decreased productivity, and I can’t diagnose it from the information provided. If you aren’t seeing flowers on the bushes, it could be the result of a soil nutrition deficiency, cold damage on the flower buds from a late frost, irrigation problems (too much or too little), or other environmental stress on the plants. I will include a link below for best practices protocol for high bush blueberry, so you can make sure it’s growing in the proper conditions. We’ve had a lot of rain this year, so I’m less concerned about too much rain, but if the soil is compact or poorly drained, it could be keeping the root balls excessively wet. If you haven’t had the soil tested recently, it’s worth doing that, as well, as there may be an issue with soil nutrition or pH (as you no doubt know, blueberry likes acidic soil… and the pH can drift too high over time). If you are seeing flowers, but not fruit production, you’re probably looking at a decline in the pollinator population–there isn’t much you can do for that, other than planting plenty of pollinator attracting plants and getting involved in the efforts to protect beneficial insects. 20 years isn’t too old for well maintained high bush blueberries, so I’m hopeful you they can recover their former productivity.

Here are a few links you may find helpful:

UMaine Cooperative Extension Bulletin #2253, Growing Highbush Blueberries

UMaine Analytical Soil Lab (you can pick up soil test kits in any Extension office, or request that the lab mail you one)

Good luck and happy gardening.