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Guild of Oca Breeders

Oca tubers for the 2015 trials

We have joined the Guild of Oca Breeders

The following text is from the Guild of Oca Breeders website where you can find out more about the project and how to join in. We are very excited to have joined the GOB club and our first trial Oca are flourishing in the field, with even a few flowers appearing on our GOB 1358’s!

About the Guild of Oca Breeders

Set up by @Rhizowen 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, as the delicious tubers start forming when nights get longer at the end of summers, 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.

Oca trials in the field
Oca trials in the field

Join in!

We are looking for committed breeders, with a minimum of intermediate gardening experience, who will help us further the Guild’s objective to create open source and genetically diverse, day neutral oca.

We are planning to grow to be a membership organisation by next year, so we are trialling our model with a few participants to start with. We will send you some oca (on receipt of a p&p contribution), ask you to grow the tubers, assess them according to the criteria that we will publish on this website, and select any that meet our requirements for sending back to us. You will be able to keep any extra tubers for eating or growing on.

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.

Find out more at and join the guild on twitter @ocabreeders