The Aberystwyth-based company has been chosen for the rolling contract to print two titles, The Orchid Review and The Plantsman.
The Orchid Review is a 64pp-plus cover title that enjoys a bi-monthly print run of 1,750, as well as a quarterly mono supplement.
The Plantsman is also 64pp but features a 4pp cover and 3,750 copies are produced four times a year. Both editions are printed on HannoArt Silk stock.
Cambrian Printers, which is also providing a fulfilment service for both RHS titles, is producing the titles on its Heidelberg Speedmaster that includes a six-colour B1 machine.
Royal Horticultural Society production manager Diana Levy said: "Cambrian Printers has really helped us out. They've done an excellent job, a massive thumbs up!