Blueberries are a superfood that are easy to grow. They are hardy plants, but they do require a fairly acidic soil and the right temperature conditions. There are several reasons why your blueberry bushes might not produce any fruit, but all are easy to remedy. Also bear in mind that they ripen at different times, so you will have to pick the fruit regularly throughout the ripening season.
Lack of water
Dry seasons can result in your blueberry plant not yielding much fruit. They must be watered frequently and the soil should be kept moist by adding a thick layer of mulch, around 10 to 15 cm (4 to 6 inches) should be enough. Use rainwater if possible, but tap water will also work.
Not pruning your bushes will mean too many old branches that no longer produce fruit, and too few young replacements. You don't need to prune during the first three years, but after this time the bushes should be pruned annually. Prune in the spring, removing branches that are old and have been damaged in the winter.
Having just one plant
A single bush will produce far less fruit than if you plant two different varieties and allow them to cross-pollinate. The blueberries the plants yield will be much bigger too.
Temperature too high
Blueberries need a dormant period -- they need some cold weather to be able to produce fruits. They typically need to be kept below 8 degrees for 750 hours per year. If your blueberries are in pots, don't move them to the greenhouse in the winter.
In the first two or three years you can expect the yield of blueberries to be fairly low. However, once they've past the five-year mark it should increase considerably.