The company now wants to make its Greencup product available at independent garden centres and is trialling it at Chelsea Physic Garden as a snail repellent.
Redcup office coffee machines supplier Jeremy Knight now collects waste coffee, which is dried in furnaces at a processor on the England/Wales border.
Project manager Adam Fairweather said the £4.99 product, available in 5kg hand-stitched bags, is now on sale at Camden Garden Centre and Rassells Garden Centre in London as well as White Moss Horticulture's two centres in Merseyside and Chester.
He added: "We saw what Starbucks was doing giving away coffee and saw how we could do that." Green Cup plans to set up its own processing factory.