Designers expected to source plants from Howard include Ann-Marie Powell for the British Heart Foundation Garden and Thomas Hoblyn for the Homebase Garden.
Hoblyn said: "Howard Nurseries is growing 3,437 perennials for us and I’m getting some plants from other nurseries for them to grow on for me. David Howard has a lot of expertise in growing for Chelsea and I value his input."
Howard Nurseries owner David Howard said: "Sponsorship for the gardens seems to be quite positive this year and we are very delighted to be supplying them."
Other growers favoured by Chelsea designers include Hardy’s Cottage Garden Plants, Crocus and Deepdale Trees. Robert Myers intends to source his plants from Crocus and Deepdale for the Cancer Research UK Garden. He said: "We’ve chosen these two because, for Chelsea, they have a lot of experience in knowing what’s required."
Going head to head among the 18 show gardens will be Gateshead and Leeds councils, DIY stores B&Q and Homebase, Australian gardens from Flemings Nurseries and RBG Melbourne and coastal garden designers Robert Myers and Thomas Hoblyn.