The charity is calling on anyone with a classic or sports car to take part, commencing from Studley Green Garden Centre, near Stokenchurch in Buckinghamshire.
The rally will then lead drivers out in to the Cotswolds taking in points of interest from across the area, before finishing the day in Ascott Under Wychwood, at The Swan at Ascott.
One of the sponsors of the event is Boyd Douglas-Davies, chief executive officer of Hillview Garden Centre, which includes the Studley Green Garden Centre where the rally will start, and Squire’s managing director Dennis Espley has already signed up to take part.
Greenfingers are hoping to attract others from the industry, and beyond, to sign up and take part with all funds raised from the event going to the A Million Moments Appeal which aims to raise £1 million to help a further 5,000 children who are involved in the hospice system to benefit from inspiring gardens and outdoor spaces.
Fundraising head Linda Petrons said: "We are very excited to be launching this new fundraising initiative this summer – what could be better than a day driving around the fantastic Cotswold countryside whilst raising money for charity? We really hope people will be inspired to sign up and take part – in whatever car they have – and be part of what is set to be a fun and worthwhile day out."
Participants are being asked for a registration fee of £100 per car to take part.