I really like the Hydrangea "Everlasting" series for contrast with our standard hydrangea and for cut flower (we have > 80 kinds of hydrangea at home near Seattle, WA). From the series we have 'Pistachio' (= 'Glam Rock' = 'Horwack' as original name) and 'Amethyst' both are mid-sized compacts.

Yesterday I picked up H. mac. 'Sharmrock' it looks in the same series but is less coarse/stocky in shape and significanrly smaller and more compact than 'Horwack' all parts being at least 30% smaller so my blooming plant as purchased in one gallon pot is almost 1.5' tall now. It was right next to 'Horwack' so you could see it was distinctly smaller and quite different in every aspect. So it should make a great container hydrangea. I think I remember seeing a photo of it as a series with the other two a few years ago from perhaps Ball Ornamentals and they showed it going very green and not having the distinct color modeling of 'Horwack'. It goes through similar color shifts for the series. I'm having trouble now finding internet info about it. Most info I can find with the 'Shamrock' name is for an attractive Japanese light pink colored, lacecap with parse floret flower number in the flowerhead. Anyone know more about my 'Shamrock'?

Hydrangea macrophylla 'Shamrock' These photos came out light. Leaves are more deep green and flowers more pink-merlot in color.

Hydrangea macrophylla 'Horwack' in photos below from last year in our yard.