This is Limelight Hydrangea. I cut it down in March in a semi-circle so that it will bloom throughout the plant and not just on top. It grows to about 7 feet tall and just as wide. Limelight enjoys full sun but will bloom in part shade. Fertilize with an acid fertilizer in the spring and again in the early summer. The blooms begin a white with a tinge of green, then turn greenish and then pink to rose to tan in the winter. I cut them at three stages and leave some dried tan for winter interest. The is a spectacular plant and will draw many comments from those who pass by.
The flowers are large and fluffy, somewhat pendulous but not bending to weigh the plant down. If not shaped in the spring it will get many blooms on top and tend to look top heavy.
This is Unique Hydrangea and it can grow to eight feet or more. I shape it to about two feet tall in the spring and it grows to about six feet on my tight north side of the house. I love this one, it is so Victorian, white, then white with pink then rose. It is unusual because it has many seed heads showing amongst the florets.
The panicles are about twelve inches long and last for years when they are dried.
This is my daughter-in-law's Pink Diamonds Hydrangea. We shaped it in the spring because it had been let go to the point where there were only blooms at the top. It will probably take another year before it is a full shape with flowers throughout. It is more upright than Unique, not as pendulous, flowers not as large, but does go through the full range of colors until the end of the seasons.
You can have beautiful hydrangeas with the proper shaping and feeding. All of the above hydrangeas grow on old and new wood so it can only help each year to cut out any dead branches, not to worry about bringing them down to a size that will work on your property, don't forget to feed!