General Plant Information (Edit)
Plant Habit: Shrub
Life cycle: Perennial
Sun Requirements: Full Sun to Partial Shade
Partial or Dappled Shade
Water Preferences: Mesic
Soil pH Preferences: Neutral (6.6 – 7.3)
Plant Height: 3 - 5 feet
Plant Spread: 3 - 4 feet
Leaves: Good fall color
Fruit: Dehiscent
Flowers: Showy
Blooms on old wood
Blooms on new wood
Other: Rebloomer
Flower Color: Multi-Color: Pink to Blue to Violet
Other: Color depends on soil PH.
Flower Time: Late spring or early summer
Late summer or early fall
Wildlife Attractant: Bees
Propagation: Other methods: Cuttings: Stem
Cuttings: Cane
Pollinators: Bees
Miscellaneous: Patent/Plant Breeders' Rights: PP20,176
Parentage: Penny Mac x Lady in Red
Child plants: one child plant

Alternative cultivar names:
  • 'Piihm-1'
  • 'Piihm-I'

Trade name information:
Series: Endless Summer®
Trade Name: Twist-n-Shout®
Cultivar name: 'Piihm-1'
Common names
  • Lacecap Hydrangea
  • Hydrangea
  • Bigleaf Hydrangea

This plant is tagged in:

  • Posted by frankrichards16 (Clinton, Michigan - Zone 5b) on Mar 4, 2018 8:36 AM concerning plant:
    Developed by Michael A. Dirr (University of Georgia Research Foundation, Inc). A cross-pollination of Hydrangea macrophylla 'Penny Mac' and Hydrangea macrophylla 'Lady in Red' (PP15175, 2004) producing the first re-blooming lacecap hydrangea. Marketed as Endless Summer® Twist-n-Shout® it has pink or periwinkle blue flowers and blooms on sturdy red stems. Note that the remontant trait comes from 'Penny Mac' while the lacecap flowers and red stems are from the female parent 'Lady in Red.'

    After Professor Dirr retired in 2003, he co-founded Plant Introductions, Inc. (or PII). Thus the registered name 'PIIHM-I' (PP20176, 2009) can be deciphered where HM stands for Hydrangea macrophylla and the -I represents the first one. A name that is often mistakenly printed as 'P11HM-1' or 'PIIHM-1' where one or more of the "I"s are replaced by the number 1.
  • Posted by eclayne (Pioneer Valley south, MA, USA - Zone 6a) on Dec 27, 2016 7:07 PM concerning plant:
    The proper spelling of this cultivar's name is questionable, possibly due to the use of san serif script.

    US PP20,176: Piihm-1 (but spelled Piihm-I in the body of the patent).
    Ca PBR3,688: Piihm-I
    AU PBR: Piihm-1
Plant Events from our members
chelle On September 16, 2014 Transplanted
Moved to W window hugel area, far NW corner.
aspenhill On July 20, 2014 Obtained plant
Betty's Azalea Ranch - qty 1
Catmint20906 On June 2, 2015 Bloomed
MissMew On May 18, 2018 Miscellaneous Event
Plant had rough winter but is now coming up from the ground
MissMew On June 2, 2016 Miscellaneous Event
Suzanne replaced plant
MissMew On September 1, 2014 Obtained plant
christine2 On May 25, 2020 Obtained plant
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