Like the kiwifruit from China, this Andean crop mostly known as Oca seems to have been adopted by New Zealanders as their own! The tubers appear to have arrived on a whaling ship in the mid 1800s and earned their place in our gardens and store cupboards! Not to be confused with the large ‘yams’ which we know here as sweet potatoes, these fellows are actually related to the weed oxalis, which itself produces tubers and similar looking leaves – which are also edible.
Yams are a great crop for home garden and food forest alike as they are so easy care and untroubled by pest and disease. One tuber will produce a mound of attractive, shamrock-like foliage about 30cm high and wide. This can be lightly picked for salads, though an over harvest of leaves will deplete your tuber crop. The mass of leaves and stems forms a great ground cover so they can be inter-cropped with other summer vegetables to reduce weeding, or used along the sunny edge of a food forest system to the same effect. The trailing stems can be partially buried to encourage larger crops of tubers.
NZ Yams need a long growing season – which is why purchasing potted plants is great as it gives you a 2-3 month head start. If you don’t have garden space or are worried about them spreading you can grow them in a large pot – just pot them on when you the pot you receive from us has filled out. Tubers form in late summer once there are less than 12 hours of daylight, and can be harvested once the tops die down. Although a frost will kill the green tops, the tubers are hardy to about -5 degrees C, and if your temperatures do not go below this they can be left un the ground until required. Otherwise they can be harvested and stored in a cool spot. When first harvested the taste is tangy and lemony due to the oxalic acid content, but this can be reduced by exposing the tubers to UV rays in sunlight, which breaks down the acid and increases the sugar content.
NZ yams are high in carbohydrates, folate and vitamins A and B6. They can be used like potatoes or mashua – steamed, boiled, mashed or baked, or try them in coconut based curries. They can apparently be used as a dessert in pies or crumble along with rhubarb or apple but I’ve never tried this!
They enjoy full sun and a fairly rich soil with plenty of organic matter.
Certified organic plant in 9cm pot – you are receiving a potted rooted tuber with leaves as per main photo.
Freight: We can send up to 9 plants this size (in 9cm pots) for the same freight price or they can be combined with other grades but this will incur higher freight costs.
Photos: Kahikatea Farm