Q.Can Anyone Help Me With 3 Problems In My Garden?
First, the leaves on my macrophylla hydrangeas are turning yellow and falling off. Try to mostly water from bottom but had several weeks of rain in April. Second one is my gardenias planted in containers. Most of the buds are turning yellow before they bloom. Last, blueberry bush has something and I have no idea what it is.

Certified GKH Gardening Expert
Unfortunately, your photos did not come through. I am unable to assess the damage. It does sound like overwatering, and generally wet soils, have left the area with a fungal or bacterial infection. Fungicides will be necessary, should this be the case.
The blueberry may have an infection, as well, but most of the time blueberries suffer form the wrong feed. Nitrates will kill blueberries, so fertilizers should be ammonium sulfate based, rather than ammonium nitrate based. This will, also, mean that it will be necessary to check the soil it is planted in. Most soils are amended with nitrates in some form.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/mophead-hydrangea-care.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm
https://www.gardeningknowhow.com/edible/fruits/blueberries/growing-blueberry.htm