Sainsbury is proposing a 3,000sqm store and an employment complex on the site of Malmesbury Garden Centre in Wiltshire, which would bring 200 jobs to town.
And a new Waitrose store in the Wootton area of Northampton, measuring 1,500 sqm, is being proposed next to Garden Centre Group's Northampton Garden Centre.
The plans were put on display in a marquee in the garden centre car park last week.
A planning application is set to be submitted at the end of the month and, if approved, Waitrose hopes to open the new store by autumn 2012.
The building of the store would also result in a number of improvements to Northampton Garden Centre including a new customer entrance, an extension to the cafe and a new service yard.
Waitrose is also planning a garden centre alongside Garden & Leisure's Percy Thrower centre in Shrewsbury, which would see the garden centre rebuilt.
Marks & Spencer have proposed to develop a new retail park where the current Stephen H Smith Garden Centre is situated in Scunthorpe.
Morrisons is believed to have made a preliminary bid for Garden Centre Group, which could lead to Britain's two biggest garden centre companies being owned by supermarkets, with Tesco owning Dobbies.