The 15 garden centre group had growth of 19 per cent, with five per cent on a like-for-like basis, and saw profits rise by 77 per cent.
Income is split 50/50 between gardening and non-gardening. Overall annual sales are expected to reach £83m by the end of the year.
Blue Diamond bought Trelawney Garden Centre in December 2014 and Newbridge Nurseries in January 2015.
Managing director Alan Roper said: "The outlook for the full year is positive and the group expects strong sales at Christmas thanks to new stock coming in from the US. The group continues to look for opportunities to acquire new sites at the rate of two every year and is actively redeveloping its existing portfolio of stores."