Question
I was given two plants that are sort of dark red and the names are hydrangeas 'mahogony pita'.  Are these annuals or perennials?  They are about 12 inches high now and have grown considerably in the past month.  How tall will they get?  Thanks for your help.

Answer
Pat,
I'm not familiar with a hydrangea named 'mahogony pita' but in general, most hydrangeas that have blue, red or pink flowers are only hardy in a US zone 6 and above. If the winter temperatures get below zero they die to the ground and although they might live, they don't flower the next summer. There is a short variety called Pia, and if that's what you have it will grow to 12 to 18 inches tall. It flowers best when the winter temperatures don't go below 15 degrees.

Since I don't know where you live it's impossible for me to say if they will survive the winter and bloom again next year - but you can use the temperature guidelines above as a gauge.  

I hope this helps,
C.L.