OCA PRODUCES MULTICOLOURED tubers with a very distinct lemony flavour when raw, and nutty when cooked. It is harvested at this time of the year. Oca tubers are a good source of calcium, iron and carbohydrates.
Sowing
Getting your hands on oca tubers to sow will probably be the hardest part of growing them. Check out good garden centres, or good online horticultural retailers like Mr Middleton, The Organic Centre, Seed Savers or GIY. Or ask at your local GIY group.
Oca can be grown happily outside but might produce a better crop in a polytunnel or greenhouse. You can either sow your oca tubers in pots for later transplanting or sow them directly in the soil.
Sow in pots
Sow individually in 15cm pots filled with multi-purpose compost in April. Leave the pots indoors as the emerging tips are frost-sensitive. Plant out in late May when the risk of frost has passed. You might want to keep them covered with fleece if growing outside.
Sow directly
Sow in May directly in the soil about 10cm deep. The advice of spacing oca plants varies – anything from 30 to 90cm – they are quite a bushy little plant so I would allow around 40cm or so to give it room to grow. The more space it has, the more tubers you will get.
Growing
Oca plants are slightly unusual looking – they are bushier than a potato plant with more decorative leaves. Similar to potatoes, oca plants are ‘earthed up’ during the growing season – that means that we draw soil up around the plants to encourage more tuber development.
Regular watering is also essential, particularly from September on (if dry) as this is when the tubers are starting to form and need water to grow bigger. A mulch of compost or other organic matter in the summer will preserve moisture and also feed the plant.
Harvesting
Unlike potatoes, which are harvested from summer onwards, with oca you are better to leave them alone until very late in the year – November or even December if possible. This is because oca plants do not produce their tubers until late in the season.
The plants may well be killed off by a frost in early winter, but the tubers are still forming (with food moving down from the stems of the plant to the tubers), so leave well alone. Harvest and dry the tubers, handling them carefully not to damage them.
You will get about 15 tubers from each healthy plant. Store in a hessian sack or a box of sand in a frost-free place until the spring. When they start to sprout in the spring, you’re ready to start planting them again.
In the kitchen, oca has a variety of uses – basically anything you can do to a potato, you can do with oca. But generally speaking in our house it’s sort of a delicacy when we have it so we generally just bake them whole in the oven with lots of seasoning and some olive oil.
The tubers don’t need to be peeled, just washed well.
Recommended Varieties
There are no varietal names, but there are different colours of oca, everything from normal potato-coloured to yellow, red, purple and even black.
Problems
There are no major pest or disease issues. Hurrah for that.
GIY Tips
Oca is also known as “South American Wood Sorrel” and is related to the common wood sorrel. Oca leaves can also be harvested sparingly as an interesting, lemony addition to the salad bowl.
GROW HQ
The home of the GIY movement and our brand new food education centre, GROW HQ, is finally open in Waterford city. In addition to our 65-seat homegrown food café and shop, we’ve a range of growing and cooking courses happening weekly. For courses happening this month, check out www.growhq.org.
Recipe of the Week – Warm Oca and Anchovy Salad
It’s a testament to how rare oca is that you won’t find loads of recipes online the way you will for almost every other recipe. I did come across this delicious recipe on permaculture.co.uk.
Serves 4-6.
Ingredients
Directions
Cut the oca so that they are in approximately equal-sized pieces. Chop the parsley stems finely and put to one side.
Boil or steam the oca for about 10 minutes until they just give in the middle when you test them with a sharp knife. Strain the oca and leave to drain and air dry in a colander or sieve while you prepare the dressing in the pan you used to cook them.
Make sure the pan is dry. Add the olive oil and heat over a low-medium heat. You need the oil to warm the anchovies and garlic but not to brown them.
Add the anchovies, garlic and parsley stems and cook gently, stirring frequently until the anchovies have melted. Take the pan off the heat and add the oca and chopped parsley leaves to the pan.
Stir the oca gently in the flavoured oil to coat thoroughly. Check seasoning and season to taste, give another stir and tuck in.
Michael Kelly is a freelance journalist, author and founder of GIY.
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