Question
I received a Hydrangea Macrophylla Endless Summer for Mothers' Day and couldn't resist pruning two of the four large blooms for a vase. I now have two large blooms and want to know if I can plant it outside and how long before any new blooms will appear. Have I pruned too soon?

Answer
You do not give your location, but if you are in zone 5 or warmer, you can plant the hydrangea.  It is supposed to bloom all summer long, continuously, so cutting the blooms should not do any harm.  Hydrangeas in general like acidic soil and this variety must have it if you want blue flowers.  When the soil is alkaline, the flowers will be pink.  Add peat moss and a fertilizer intended for rhododendrons and azaleas (Hollytone is one) when planting.

I planted two 'Endless Summers' two years ago.  They did bloom continuously all summer.  I found that I needed to add aluminum sulfate (in addition to above recommendations) to get blue flowers.  You need to wait at least three weeks from time of application to start seeing a color change.

Last summer the plants grew very well and never bloomed at all!  I have yet to figure out why they did not.  I even talked to my woody plants professor from college and he had no idea.