Types
All hydrangeas are deciduous and shrubby. Most are bushes - the compact ones are little more than 1m tall and across, others will go to over 2m high and 3m wide. There are also climbing hydrangeas that are good on walls, even the shady North wall, and look very fine growing up a tree, eg the trunk of a tall pine.
The traditional Hortensias ( H. macrophylla) have two basic types of flowerheads:-
Mophead flowerheads are big round balls made up of lots of flowers, on the end of this year's shoots.
Lacecap flowerheads are generally flat, with lots of small flowers without big petals in the centre, and a few flowers with showy petals arranged in a ring round the outside.
The H. paniculata varieties have a lacecap-type of arrangement, but the heads are cone-shaped and often very large and showy, on the end of long stems, especially if the plant is pruned hard and then well-fed and kept watered.
The climbing types are lacecaps.