Blue berry bushs

Question

I have 2 blueberry bushs that are 4 years old. This year they had tons of berries but did not turn blue evidently falling off …..?……

Answer 1

Fruit drop can be due to environmental issues, watering, disease, pests, poor pollination, or the plants naturally thinning themselves.
This link will help refresh you on the care requirements and help you pinpoint the cause.

https://www.gardeningknowhow.com/edible/fruits/blueberries/