  We study the phenomenology of the Georgi-Machacek model at next-to-leading
order (NLO) in QCD matched to parton shower, using a fully-automated tool chain
based on MadGraph5_aMC@NLO and FeynRules. We focus on the production of the
fermiophobic custodial fiveplet scalars H_5^0, H_5^+/-, and H_5^++/-- through
vector boson fusion (VBF), associated production with a vector boson (V H_5),
and scalar pair production (H_5 H_5). For these production mechanisms we
compute NLO corrections to production rates as well as to differential
distributions. Our results demonstrate that the Standard Model (SM) overall
K-factors for such processes cannot in general be directly applied to
beyond-the-SM distributions, due both to differences in the scalar electroweak
charges and to variation of the K-factors over the differential distributions.
