The Quality Vouchers initiative is designed "to compete with the high street for the leisure pound and to improve the net profit of garden centres through increased customer visits and commitment", says Eimert de Graaff, who left HART last August.
Five garden centres, including Thirsk, Carpenders Park, Sapcote and Vermeulens, have signed up. Gardman, Suttons Seeds and Taylors Bulbs have signed as suppliers. Eimert de Graaff is also talking to Westland, Scotts, Stewart and Wolf.
He added: "The aim is to take forward the garden clubs and card-based loyalty schemes that have been in existence for a number of years now into a new, innovative and cost-effective format. Additionally, this has a much higher rate of reward for both the customer and the retailer."
Personalised emails contain dedicated vouchers with "plant of the week" offers, "buy one get one free" vouchers and gardening advice from Grow Your Own magazine. The cost per email is from 5p, a fraction of using Royal Mail at 60p per letter.
Joint founder is Ian Lucas, another HART co-founder with De Graaff.