Yacon

Yacon is another useful vegetable that originates from South America. It is mainly grown for its storage tubers that can be eaten raw or cooked.

The plant actually forms two types of tubers - a crown of small tubers with growing tips sits at the base of the stem just above the much larger storage tubers. It is the tips that are overwintered and potted up in spring to grow new plants. Just like dahlias, cuttings can be taken from shoots and easily grow on to produce a decent crop in a single growing season. The storage tubers will not grow on their own so they can all be eaten.

Yacon is described as not being too fussy about its soil and is meant to be reasonably disease free. It produces large multi-stemmed plants up to 2 meters high with large broad leaves and a light covering of small yellow-orange flowers.

Yacon plant
Yacon plant, mid July

Cultivation

Our yacon was ordered from www.realseeds.co.uk and the growing tips arrived on 10th March. They were planted in small pots of multi-purpose compost and then popped into a heated propagator. After a week they all started to show signs of life and rapidly grew into healthy looking plants.

When the first leaves appeared the plants were moved out of the propagator and left on a window sill to grow on. When it wasn't frosty they were put into a greenhouse where they grew away quickly. After a month they were growing into decent sized plants and at this time a few cuttings were taken.

Cuttings were taken from two plants that had produced more than one strong shoot each and they were taken from as close to the base of the original growing tip as possible. The cuttings were then placed in water for a few days until roots started to appear and then potted up. They seemed very eager to root so I don't think too much care is required to get them growing.

Growing tips
Growing tips as supplied in March

Growing on

The plants grew quite rapidly in warm weather and were gradually potted on into larger pots until the risk of frost passed. Some were then planted out into 40cm diameter tubs, some into large pots and two into the ground. Our soil is light and chalky so some extra compost was incorporated to provide some extra nutrients. The plants were all grown outside and were watered throughout the growing season whenever they started to wilt.

They rapidly grew into quite large plants and in July the first flowers appeared. You are meant to remove them but we only removed a few and ended up leaving most of them. They are not spectacular but, along with the lush foliage, do add some interest to the garden and we'll leave them on in future.

One month old yacon plant
One month old yacon plant

Harvesting, storing and using

We started to harvest the plants at the end of October. All the pot grown plants produced so many tubers that they not only filled their pots but started to push themselves out and deform their pots! The 40cm tub grown plant produced about 20 usable tubers with the largest being 20cm long and weighing almost 800g (1lb 11oz). In total, the tubers from this single tub weighed 5.5kg.

As there were so many tubers and new growing tips we decided to experiment with storing them. Some were left unharvested in their pots, some harvested and stored in soil in an unheated greenhouse and some in bags indoors. Sadly we had a very cold winter, with temperatures down as low as -9 C, and most of the tubers stored outside perished.

The best way of storing the growing tips for next season was to harvest the plants, remove most of the storage tubers and leave the growing tubers under a short piece of the old stem and pot the whole lot up with some dry soil and leave them in an unheated room. I think they just need to be kept frost free and reasonably dry to stop them rotting off.

The edible storage tubers gradually sweetened up during storage and we've tried using them in various ways. When raw they are very crunchy and watery but they don't seem to soften much when cooked. They don't have much flavour and as they also remain very sweet when cooked it's taking a while to get used to them. We've also tried juicing them and have made 500ml of juice from 800g of peeled tuber. Perhaps the best way we've found to cook them is to cut them into matchstick sized pieced and add them to stir-fries.

Yacon seem to be so productive it actually causes the main problem we had with them. When grown in tubs and pots the tubers press against the sides and start to fracture around their circumference, the tubers are still usable but more care is needed when preparing them. It also took some time to extract them from their pots and then we had to find ways to store so many tubers!

Plant just before harvest in October
Plant just before harvest in October
Tubers showing new growing tips and storage tubers
Tubers showing new growing tips and storage tubers, end of October
Tubers from one yacon plant
Storage tubers from one yacon plant, all these tubers can be eaten
Yacon pushing its way out of its pot
Yacon pushing its way out of its pot
Yacon flowers
Yacon flowers

Further details can be found here:

www.pfaf.org/database/plants.php?Polymnia+edulis


http://en.wikipedia.org/wiki/Yac%C3%B3n


www.greenharvest.com.au/Plants/yacon_info.html


www.newcrops.uq.edu.au/newslett/ncnl1221.htm