Single crystals of high concentration iron substituted Sm0.55Sr0.45Mn0.4Fe0.6O3 were grown by optical floating zone technique in oxygen atmosphere. Analysis of powder X-ray diffraction and Laue patterns revealed single-phase formation and crystal quality respectively. Replacement of Mn by iron has reduced the ratio of trivalent to tetravalent Mn ions thus suppressing the double exchange interactions and ferromagnetism. The grown crystal exhibits spin glass behavior below 35 K due to the competition between the Mn3+-O-Mn4+ double exchange and the Mn3+-O-Fe3+ super exchange interactions.