Bord na Mona said: "To date we have circa 400 trading stores, and we have supplied 55 of these with Pro 5 products so far, which has exceeded our initial targets for the range.
"The majority of our stockists are now stocking over 50% of the full BNM Growise portfolio (30 SKU in total). We are also expecting to see an increase this month with the release of a new promotion."
Higher peat-based growing media has seen a revival in recent years, with niche products such as Westland's Jack's Magic also being launched.
Bord na Móna bought White Moss Horticulture, which has peat bogs in Somerset, in January.
The company says some of the sales are down to research into consumer purchasing preferences, which Bord na Móna UK did in early 2016.
Bord na Móna marketing head June Dowling said: "Our commitment to research – both in terms of product development and consumer purchasing preferences – has enabled us to produce a first-class product range, raising the standard of the growing media market within the UK.
"As well as facilitating the production of a superior quality offering for garden centre retailers, our research has encouraged us to explore new distribution channels, including professional growers and agri-store retailers. 2017 has been a very exciting year for Bord na Móna UK so far and we are looking forward to continuing our progression over the busy summer period."