Some 300 companies have pledged to take part.
- Thompson & Morgan will give 50,000 Rudbeckia Cherry Brandy packs to garden centres in a bid to set a record for the largest number of seeds sown in one day.
- Garden centres will attempt the world's biggest quiz, set by celebrity gardeners.
- Scotts Miracle-Gro will host a garden party at the retailer who wins its January and February display competition. A giant cream tea party will also attempt to set a new world record.
- Garden & Leisure Group's seven centres will each hold local activities, with Cadbury working on a grow your own promotion.
- Sinclair Horticulture will sponsor hanging baskets, while Suttons Seeds will create a garden for a local school for disabled children.
- Grosvenor Garden Centre will brighten up local gardens with the help of its superhero Grosvenorman.
For further details, see www.gardenreleaf.co.uk.