Warner's Cardigan-based Quinky Young Plants, which uses the grown-inwales.co.uk website, supply to garden centres and growers with peat and chemical-free pesticides alpines and herbs.
Having seen big garden centre chains such as Dobbies in Scotland say they want more local supply, Warner says it is nice to be vindicated.
He said: "I've been promoting locally sourced plants for 10 years but only the most clued up and sharpest of the independent garden centres have taken what I offered and ran with it."
Warner says larger Welsh centres such as Old Railway Line and Pugh's have been more responsive to stocking Welsh-grown, with smaller retailers often sticking to cheaper imports.
He said: "Every plant retailer in Wales should be making space for a high quality, Welsh-grown plant on their benches. I know that they won't though. I know that when I visit garden centres all over Wales what I will see are the dregs of the big growers. They will always supply the biggest chains and DIY stores with the best varieties. It doesn't bother me now. There are enough truly innovative independent garden centres for us to make a living and I will be concentrating on making sure that they have the best Welsh-grown, peat and chemical pesticide free plants that money can buy on their benches."
Warner is using Floramedia bespoke labels with dragon motifs and bilingual writing, appealing to the strong sense of pride in the country.
He says there are opportunities for local employment through local supply. Originally, Warner saw the opportunity after seeing Welsh-labelled leeks in Tesco.
Quinky's plants have a point of difference compared to Lidl, which he says could be the biggest plant retailer in Cardigan.
He says existing customers are buying more this autumn, possibly because of exchange rates.
Warner can supply small quantities locally and says this old-fashioned way of supply is coming back.
Lantra's Tyfu Cymru has grants available for growers. In recent years, Warner was involved in the Grown in Wales project and exhibited at Four Oaks under their banner in 2014 with Pottles Premier Plants.
He uses social media to create demand on Facebook.
Warner trained at Pershore College and Warwickshire Agricultural College, and worked in the young plant industry before starting Quinky.
He specialises in Phlox, Sempervivum, and Rhodohypoxis, plus a range of culinary herbs. The nursery doesn’t buy in any plugs itself, with all plants self-propagated from cuttings.
All plants are grown in peat-free compost containing a slow-release fertiliser and Met 52 bio-insecticide to protect against vine weevil, with artificial heat and light kept to a minimum. He prefers to water and pot by hand. Where possible, plants are grown outside.
Warner operates a merchandising system where customers only invoice for the plants they sell. This means that, particularly during busy periods, he has to restock garden centre benches every week or two.