What kind of crops do you want for the future?


A range of hardy, reliable, disease resistant ones, which yield well in your area, or monocultures of ones dependent on heavy pesticide, herbicide and fertiliser use?


The Guild of Oca Breeders

The Guild of Oca Breeders (GOB) is a new and exciting project: a plant breeding club to support the democratisation of the plant breeding process and remove its mystique.

We are concentrating on a crop with a lot of potential: oca (Oxalis tuberosa).

A high altitude Andean tuber crop native to Peru, Bolivia and surrounding countries, oca has been grown occasionally in the UK for over 150 years but has never been a commercial success. The delicious tubers start forming when nights get longer at the end of summer which means that yields are currently limited by falling temperatures, declining light levels and the incidence of killing frosts.

With selection for early tuberisation, it is possible that this failing could be overcome. The same process of selection over many decades is believed to have facilitated the adaptation of the potato, now a reliable, high yielding crop, to the long day summers of northern latitudes.

An oca breeding club would speed this up the process considerably through recurrent mass selection: an extensive process by which large numbers of genetically variable seedlings are grown together; the best of these are selected and then allowed to cross-pollinate.

The seeds they produce are grown out again and the best plants are once again selected until the desired characteristics are established.

Join in!

We are looking for committed gardeners, farmers and horticulturalists with a minimum of intermediate gardening experience to help us further the Guild’s objective to create open source and genetically diverse, day neutral oca. It’s your chance to join a self funding organisation that can make a valuable contribution to the future diversity of food cultivation. Read all about what members do or subscribe here.

Our tubers are released under the Open Source Seed Initiative (OSSI) pledge: taking part in the project means you commit to keep the germplasm in the public domain.

Just want to have a go at growing oca?

If you have never grown oca, and are looking to have a go, that’s fun, easy… and tasty: so please do!

Because of limited supplies of germplasm, which are needed for our breeding projects, we are however unable to distribute ocas ourselves for the purpose of amateur growing. Of course you can access our growing guidelines, and keep in touch, and if one day you want to commit to breeding, you are most welcome to join the Guild.

There are a range of suppliers where you can find tubers (including some of the mainstream ones) – you may try:

and you can sometimes find them at seed swaps or from other enthusiasts.

Other ways to help the Guild

The GOB is a newly born project and aims to sustains itself through memberships from this year.

We need help in a range of roles, horticultural and administrative. If you have skills that you can offer on a voluntary basis, do get in touch please.

We are also getting organised to receive financial support through donations soon.

And if you have suggestions and ideas, let us know!