The obvious disadvantage of heirloom varieties is that they can’t possess modern  genetic traits. Indeed, some crop were not widely established in the UK pre-World War II. For example, Thomas Etty‘s Heritage Vegetable and Flower 2024 Catalogue lists only four varieties of sweet corn, one of which is post-War and the other three (Stowell’s Evergreen, Golden Bantam and Glass Gem) are all American. So-called ‘super-sweet’ varieties were developed from a discovery of its sh2 gene in the 1950s.

Similarly, I can’t remember as a youth ever seeing the compact bushy courgette (zucchini in America!). There were marrows (same species) which sprawled over a huge area and produced a few large fruits but not the compact varieties which can produce many small immature fruits suitable for ratatouille and other Italian-style meals.

Strong single genes for resistance are similarly generally lacking in heirloom varieties. Thomas Etty‘s Heritage Vegetable and Flower 2024 Catalogue lists over 50 heirloom tomato varieties but none of them are described as blight-resistant. Black spot fungus can completely defoliate older roses.

Modern resistances have mostly been obtained in our national and international collections of local but especially exotic landraces of crop species and their relatives. These were mainly established in the early 1900s but finding resistant types in the collections let alone breeding them into varieties took time, so making it well-nigh impossible for such resistances to be incorporated into heirloom varieties.

And some pests or diseases have become more virulent with time. Our heirloom potato varieties used to be grown unprotected outdoors but they are susceptible to the strains of late blight now present in the UK. We now have to grow modern blight-resistant maincrop varieties; fortunately, there are some good ones available including ones bred using participatory methods.

Modern varieties also generally have a much greater yield than old varieties. And a high yield is what most gardeners want!

We also appreciate the much wider diversity of fruits, vegetables and flowers. For example there is now great interest in growing Asian greens. New types of flowers are now widely grown (e.g., I don’t remember the flower Camassia as a child). Foreign heirloom varieties sometimes do well in the UK but often modern varieties especially bred for our local conditions are the only sensible options, for example, of soya (edame) beans.

Thus, there are many aspects of modern varieties that gardeners want or need. But most gardeners don’t want to lose the good aspects of heirloom varieties. Participatory plant breeding is a way to enable gardeners to ‘have our cake and eat it’. It does so by including gardeners especially in the later stages of the breeding process; in essence, modern methods obtain the initial diversity followed by an empirical process of selection.