A partial shade site for macrophylla types is best.  Others will thrive in full sun.  Oakleaf Hydrangea varieties can take shade or sun.

Dig a hole 3 to 4 times the diameter of the root ball and 1 1/2 times as deep. Next, remove the container. Container-grown plants must have their outer root system broken and spread out or they will never become established. Simply cutting the roots with a knife in 3 to 4 places is not good enough, exposing about 1” of the root systems by vigorous shaking will work. Then, place plant in hole and backfill until the plant is at a level where grown in the nursery. Then, gradually backfill the hole while tamping soil around roots with your foot. Do not break the soil ball. Follow the watering directions then mulch with about 2” of bark mulch.

Prune the stems that flowered last season - don't prune un-flowered stems, because these are going to produce the next lot of blooms. The best time to prune Hydrangeas is after they have flowered and the blooms have died. That's not to say that normal pruning rules shouldn't apply: cut back anything that's very weak and spindly and, of course, any dead stems.

Large -leaved Hydrangeas: these Hydrangeas bloom on old wood.  A severe trimming in spring may prevent blooming.  Just trim out dead wood and trim to shape in late March.

Other types: trim after flowering.

The NEW Endless Summer Hydrangea will bloom on old, as well as new wood! 

The most interesting feature of showy hydrangea flower heads is their ability to change color according to the pH level of the soil. Hydrangeas have blue flowers where the soil is naturally acidic, and pink or red blooms in alkaline soil. This gives the home gardener a certain amount of control over the color scheme of the hydrangea bed. Winter is a good time to start planning these changes - by the time the hydrangeas are in flower it's too late.

To change the color of Common Hydrangeas, add 5 to 8 Tbs. of aluminum sulfate for blue or 12 to 15 Tbs. of dolomitic limestone (pulverized lime) for pink per 10 square feet. Pull back the mulch and lightly mix into the top layer of soil and water thoroughly. It may take 2 years for a complete color change.

Water at initial installation.  Use as much water as necessary to thoroughly soak plants and wet entire bed.  Then, water the plant every 3 days for 3 weeks.  After the 3 week period, water only when necessary. Check soil moisture around plant before watering.  Remember, Hydrangeas are high water users, and, during hot periods, should be kept well watered.  If temperatures are above 85°F, more frequent waterings may be needed.

Fertilize approximately on April 1st, May 20th, July 4th, August 15th and October 30th. Use an acidic fertilizer such as Holly Tone. If using a liquid fertilizer, do not apply it to the blooms of the plant.