Nyeri farmer reaps big returns from aerial yams

Aerial yams grown by Nyeri farmer Jackson Kanyingi. PHOTO | JOSEPH WANGUI | NMG
Aerial yams grown by Nyeri farmer Jackson Kanyingi. PHOTO | JOSEPH WANGUI | NMG 

Irish potato production cost has for some time continued to rise as its yields fall. Seasons when there is a bumper harvests mean there is excess supply and therefore fetch low prices.

Caught up in such a lose-lose situation, Jackson Kanyingi, a farmer from Ngangarithi area in Nyeri embarked on a search for an alternative crop.

The search took him to a relative in Mathira sub-county who had bought yam seeds from Nigerians who had attended an agricultural event at Moi University in Eldoret.

The relative, he said, told him the crop would turnaround his fortunes.

“I got interested and carried some to Nyeri. They surprisingly did well and I later did further research on the Internet and realised they have many nutritional and medicinal advantages,” he said.

The plant is known as air potato or aerial yam, owing to the way it twists on supporting structures producing its fruits off the ground, much like passion fruits.

The propagation of the crop is either through planting of seeds, which are costly and not widely available locally, or by planting bulbils from harvested plants.

Being among the first few growers who took to aerial yam farming, Mr Kanyingi has become the to-go-to person for the yam bulbils.

The high demand for his bulbils has been egged by the realisation among locals of the crop’s high yields compared to its low cost of production.

Mr Kanyingi said the plant saves on production cost as he does not need to look for new planting materials after harvesting.

“If grown under proper care, a single plant is capable of producing 25 yams of over 20 kilos. I sell the yams all over the country including agricultural research institutions,” he said.

He sells a single yam at Sh100 when bought for consumption and Sh200 when it’ll be used as a planting material.

This means he makes between Sh2,500 to Sh5,000 per plant, assuming each of his plants bears an average of 25 yams.

He has planted around 300 plants in a half-acre piece of land, earning him between Sh750,000 to Sh1.5 million per year.


With such returns, Mr Kanyingi plans to increase the acreage under the crop to one acre so as to maximize his earning from the plant.

The yams are planted just like irish potatoes, but for maximum yield one needs to dig a hole of about one square feet and apply about a bucket of well decomposed farmyard manure, mix the input properly with the top soil before application into the hole.

The seed should be planted at a depth of about 1.5 to 2 inches.

Aerial yams can grow to a height of about five to 10 metres and so spacing during planting should be about 10 by four feet.  One does not need to worry on how to pick the bulbils as they drop on the ground upon maturity.

Farmers are advised to plant bulbils after they start producing shoots for fast germination. Germination can take place in about seven to ten days followed by budding, which occurs after three months of planting.

“Out of the harvest, a farmer should keep some of the best bulbils for planting and the small ones for consumption. Bigger yams produce relatively high yield than smaller ones if planted,” he advises.

The bulbils are ready for harvesting in eight to 11 months from planting. The vine wilts and dies off at the end of each growing season and the underground tuber sprouts again in the next rainy season making the yam a perennial plant.

This means that the underground tuber is capable of producing a vine annually. After peeling, the yams can be fried, roasted, deep fried, baked, mashed, used in preparation of chips or boiled.

Shelf life

Value can also be added by slicing them into pieces and grounded into flour increasing their shelf life.

But Mr Kanyingi insists that the best way of preservation is to boil them to ensure their nutrients are retained.

The crop is also widely grown in tropical Africa especially in Nigeria, and in Asia and Australia.

They are however not without downsides as other than theft, they are adored by ants and moles which feed on the underground tubers.