Modern and heirloom varieties were bred using quite different approaches.

PPB amalgamates the empirical and scientific approaches which created heirloom and modern varieties respectively, largely by involving both the customers of new varieties  and plant breeders in the development of new varieties,  using the ideas of citizen science to bring the two together.

It is particularly based on using the scientific approach to identify the parental material and the breeding method but, in the case of garden varieties, involving gardeners selecting, largely empirically, in their gardens or smallholdings. In this way, it tries to achieve the best of both worlds.

Participatory plant breeding (PPB) is based largely on the concept that the users of varieties (farmers, smallholders, gardeners etc) and their professional breeders each have useful but different knowledge, experience and facilities for plant breeding and they achieve maximum success by combining forces.

Although PPB appears self-evidently to make sense, it has one less evident but major disadvantage. This is that maintaining ownership of breeding lines is difficult in PPB, partly because, unlike most farmers, gardeners may be quite poor so it is not worth suing them if breeding lines distributed to them become misplaced. And ownership of breeding material is very important for most commercial seed companies.

As a result, adoption of PPB for gardeners has been slow and mostly involves plant breeders and other researchers based in universities, government research institutes or not-for-profit set-ups (e.g., projects at the Organic Seed Alliance website) that are less concerned about ownership than for-profit commercial seed companies.