Peonies

As you said, peonies like full sun (6 hrs./day). Plant them in a place where you feel they will stay since they don't like to be disturbed or moved. When you water them do it deeply, i.e. a long time so the water gets to deep roots. A quick, short watering is not good for peonies. Fertilize them in the Spring with a 1-2-1 ratio such as 5-10-5. The first number is nitrogen which is for foliage health and color. the second number is for phosphorus which is good for the flower. The third number is for potassium and it's good for stem strength which is important for peonies.

Transplanting

I'll be transplanting several azaleas this fall because they have overgrown their area. Fall is an excellent time to do this as the plants go into dormancy plus they won't be fighting the hot summer weather for survival. By the way, speaking of azaleas, the best time to fertilize them is after the blooms fade and again in the fall. the best time to prune azaleas is also right after the blooms fade. If you wait too long to prune you will cut off the buds for next season and won't have any spring flowers. You have the same issue with cutting off the dead-looking leafless stems of hydrangeas. Don't use the day after Thanksgiving as family time to cut back those "dead" hydrangea stalks. You will be cutting off the buds for next year.

For hydrangeas that bloom a second time (called remontant) you can encourage the second round of blooms by cutting off the spent blooms from the first round. The sooner you do this the earlier your plant will start the second blooms. When you cut the spent blooms make your cut just below the flower. For hydrangeas that don't bloom a second time keep the blooms on the plant as long as they look attractive. The flower will change to a pink shade even if it was originally blue. Cut them before the first freeze and you will have a good looking dried plant for your house.

One way of knowing if you need to water your hydrangeas is to check them in the morning before the sun has started to heat them up. If the leaves are already starting to droop they need water. Conversely, just because the leaves are drooping in late afternoon it doesn't mean they need to be watered. You can also feel the soil and if it's dry at 2" it needs to be watered and you can clean your dirty hands as you water them.

What is needed to have blue flowers for your macrophylia hydrangeas? An acidic (ph 4.5-6.0) soil will result in a blue flower. The acidic ph releases aluminum in the soil which makes the blue flower. If color is purple to pink or red add aluminum silicate per instructions on the container to drive the ph down. Pine needles around the plant will also help lower the ph. If you want pink or red instead of blue add lime to the soil. this will move the ph up to basic and retard the aluminum from getting into the plant.