Co-owner of the Knaresborough, North Yorkshire-based company Richard Kay said the increased sales were "indicative of the market and the hard work we have put in during the last five or six years to build the brand.
He said sponsorship of the BALI awards and World Skills, more social media promotion and "making sure we always deliver the goods" were helping sales.
Kay added that being a one-stop-shop and adding more storage capacity at its new Rabbit Hill business park premises and the country store were beneficial too.
Latest stated turnover for the year to 30 September 2016 was £10.3m.
Green-tech opened the doors to its offices, production facilities, warehousing and distribution operation last week.
More than 150 customers and suppliers attended the open day.
Guests were invited on a tour. A number of seminars that covered John Chambers Wildflower Seeds, the ArborRaft system and Green-tree topsoil’s took place hourly. Visitors were invited to demonstrate their skill at Beat the Green-tech Goalie.
Some 70 people joined the Green-tech team for dinner at a Harrogate Hotel, raising £476 for Physcap.
Head of sales Richard Gill said: "The open day was a great opportunity for us to bring our customers and suppliers together and to meet the entire Green-tech team. Guests could tour the premises and preview our latest product developments. Many of our suppliers and customers have been trading with us for a long time and the day provided the perfect platform for us to thank them for their loyalty, commitment and support."
Wayne Dand, director at Ashlea Limited said "I thought your invite was well received and attended by all clients, architects and colleagues within the industry. You all must be very proud in the direction Green-tech is travelling; securing the number one supplier in the UK to the landscape industry. Well done for organising the event, keep up the great work."
Simon Ellis, director at NT Killingley, said: "Many thanks for a great day and evening. I learnt something at the soils talk, so has to be a good day. The hospitality was particularly good and I look forward to both companies having a busy season."
Sean Towey, regional director at TCL Group said "Your set up was very impressive. The presentation of your office, stores and yard was outstanding, as was the friendliness of staff, alongside the comprehensive approach you take to the business, left me in awe of what a genuinely simple (in the best sense of the word) yet effective set up you have; clearly defined by the ‘inclusive’ approach with your staff using technology for your market edge."
Stuart Simpson, Director at Ashlea emailed "Thanks for your splendid hospitality and the invitation for the day and evenings events. It’s good to get to see a supplier’s facilities and first-hand look at how things happen. I look forward to the season ahead and working on a number of schemes together."