School Growing Experiments

Free Oca tubers to grow in school!

In Spring 2015, as part of our Grow Around the World project 70 London schools joined our school's experiment to see if oca could rival the potato on their school dinner tables!

What is oca?

Oca (Oxalis tuberosa) originated in the Andean Highlands. It was taken to other parts of the world in the 19th century as an alternative to the potato, and even grown in Europe since the 1600’s. Oca tends to have a slightly tangy lemon taste .

By joining the oca schools experiment, schools agreed to:
•    Tell us how you found oca to grow.
•    Send us some information about your harvest
•    Tell us what you think oca was like to eat.
•    Add your oca photos on our schools Flickr gallery.
•    And send us your oca recipes for publishing on our website!

For those of your who were lucky enough to order your oca, we hope you are having fun growing. Keep us posted with your experiment on Twitter and Flickr!

Oca growing advice

• Download our Grow Around the World activity pack (above) for oca hints and tips.
• www.realseeds.co.uk/unusualtubers.html
• http://oca-testbed.blogspot.co.uk

Photo: Oca growing in the garden at Bonneville Primary School in Lambeth in September.

Oca schools experiment updates

Oca - September 2015 Update

We hope that the your school gardens are looking fantastic after the long summer holidays. If you are growing the Oca which we sent you last February hopefully it is growing well and looks a little like the photo above. Please remember it is not ready to harvest yet! The Oca tubers have not yet developed in size and will only do this as the daylight length shortens.

What you can be doing now is to remember to water your plants well, at least once a week if we have a dry Autumn. If your plants are very tall and leggy, 'earth' them up like potatoes. That means get some good soil or compost and cover the stems so that only about 15cm of the top of the plants are showing. This will encourage more root growth and more tubers to develop and therefore a bigger crop.

Harvest time - We will send you more information in November when it will become time to think about harvesting those wonderful tubers.

Oca - November 2015 Update

You should any time now be thinking of harvesting your oca plants.

The recent frosts may have caused the leaves of your oca plants to have wilted and died. Don't panic as the frost was only short lived and should not have damaged the tubers in the ground but try to get them dug up in the next couple of weeks.

If you haven't been affected by the frost
Your plants may still be growing and the leaves will still look fresh. If you want to harvest the tubers now you could just 'lift' one plant to see how large the tubers have become. Don't be disappointed by their size, if you remember when you planted them how small they were.

Oca for your Christmas dinner!
If your plants are still growing you may wish to leave the plants until December, as we mentioned in our November schools e-newsletter, and then you could add them to you school Christmas dinner as a 'roast potato' alternative! You can sign up to our free schools e-newsletter here.

Harvesting your oca
To harvest the oca tubers use a garden fork to lift up the whole plant similar to how you would harvest potatoes.

Record your crop - as part of the School Growing Experiment
Whatever the result please take some photos of your crop and PLEASE fill in the results form and send them back to us (see below). This gives Garden Organic very valuable information about how well oca's grow in our climate, contributes to people science, and is great for student learning.

Growing oca again next year
If you would like to grow some oca again next year keep a few of your best tubers to plant in late March as you did this year. Keep as many tubers as you want plants or have space for. Using the best tubers you have harvested will ensure your crops improve year on year. Make sure the tubers you keep are dry, put them in a paper bag and store in a cool dry environment, NOT in your classroom as this will be too hot. An outdoor shed or unheated storeroom should be fine.

E-newsletterspecial: Time to harvest your oca! (Nov 2015).

Completed oca experiment forms

Please send your completed oca growing experiment form, oca recipes, photos and drawings to us by Thursday 17th December 2015. Here are downloadable Word and PDF versions.

Return this form to: Food Growing Schools: London -

*Note oca tubers vary in colour from pink to white.