Ytterbium garnet and holmium garnet single crystals are of interest from the viewpoint of magnetic frustrations in the low-temperature region. Reports on the magnetic frustrations of these single crystals are rare, since it is difficult to grow them. We grew these single crystals using the floating zone (Fz) technique and carried out characterization from the viewpoint of crystal growth conditions, including seed crystals, stoichiometry, post-annealing and growth interface shape. Crystal state proved to be dependent on these growth conditions. (C) 2008 Elsevier B.V. All rights reserved.