The charity, which already sells a limited range of ambient goods through its own shops, is developing an initial range of up to 30 lines spanning sweet and savoury pies, gravies, sauces, soups, beer, bread, fresh beef and lamb, bakery items and fresh produce.
Pembrokeshire Potatoes (rsp: £1.50 for 2kg) go on sale this weekend in Asda, as part of a phased launch.
The charity is currently in talks with all the multiples about listings, with a view to rolling out the initial range by Easter 2010. The items will all contain produce grown on National Trust land or created from its archived recipes.
Accessibility and affordability would be key, said Daniel Avener, MD of The Licensing Company, which is co-ordinating the range and the licensed suppliers.
"The National Trust is very different to Duchy; its appeal is much broader," he said. "The types of products we're launching are quite different, as are the price points and positioning. It is widely reported that Duchy products can be rather expensive and that's not where we're aiming.
"This is much more about our mission 'forever, for everyone' and therefore everyone should be able to engage with the brand. We'd like to see the range grow to about 100 SKUs, but they must be relevant and with a strong link to The National Trust."
The charity is also this month launching a Viceroy India Pale Ale (rsp: £23 for 12 bottles) from Kent-based Westerham Brewery. It will initially be sold through the brewery and 200 pubs in the south east.
The range will be promoted through The National Trust Magazine in the coming months, with above and below-the-line advertising planned from next spring.
The National Trust made its first foray into the supermarkets last year when it started selling fresh beef in Booths, but the beef does not feature the charity's branding.