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Sweet and sour side of Irish potato business

By Jennifer Anyango | August 21st 2021
By Jennifer Anyango | August 21st 2021
Farmers harvest potatoes at Kidawa Village in Olkalou Constituency Nyandarua County [John Githinji, Standard]

Potatoes are the second most important food crop in Kenya after maize, according to the National Potato Council of Kenya (NPCK).

They are popular and marketable. Money Maker spoke to Victor Kariuki an Irish potato farmer from Molo on production for commercial purposes. The popular varieties in Kenya are Kenya Baraka, Sherekea, Purple Gold, Kenya Mpya Roslin Eburu, Feldelslohn, Annet and Dutch Robin, among others.

Site selection

Land set aside for potatoes should not have been under any other potato family crops or tomatoes, capsicum, eggplant for at least four seasons. This is to avoid soil-borne diseases and pests.

“Avoid poorly drained or rocky soils. Plough your land, dig the field thoroughly to remove weeds and to break lumps of soil for good air circulation and to allow tubers to grow. Mix in well-rotted manure and ensure the soil surface is smooth,” says Kariuki.

Seed selection

Buy certified seed tubers from agents approved by Kenya Plant Health Inspectorate Service (Kephis). Potato seeds should have four to five small sprouts growing out.


Kariuki says potatoes should be planted in rows.

“Make furrows 75cm apart and 25cm deep, to allow tubers to easily expand and also make harvesting easier. They will also be less pest attack on ridged potato,” he says.

Apply Diammonium phosphate (DAP) at the rate of 200kg per acre at planting. On acidic soils with a pH level of below 5.5, use Monoammonium Phosphate (MAP 11 per cent nitrogen and 50 per cent potassium) at the same rate. In this, fill a half litre container with the fertiliser and apply uniformly in furrows 15 metres long or 50 tubers planted at a 30 cm spacing.

Place the seed tuber in the furrows with the sprouts facing up. Plant before the rains begin. Cover the tubers completely after planting to avoid sun scorching.


Weeding of the crop starts once the potatoes have grown above the soil. When your potato plants are between 15 to 25cm tall, heap soil around the roots. This gives more space for the tubers to grow big and reduces chances of turning green.

“Common pests and diseases to watch out for include Early Blight, late blight, brown rot, potato tuber moth, potato leaf rolls virus and potato viruses,” says Kariuki.

He adds: “Signs of late blight are water soaked spots on leaves and dying of stem tips which turn black. Spray fungicides on affected crops when you notice the first spots. For effective control, spray the underside of the leaves.


Harvest the potatoes when the leaves start to turn yellow. Do not leave mature potato tubers for more than two weeks in the soil to avoid insect attacks and rotting. Before harvesting, the farmer should make sure the skin of tubers has hardened.

“To harden skin, let plant tops dry naturally or cut the top of plants two weeks before harvest, when the potato tuber skin is hard, it is not easy to damage at harvest,” says Kariuki.

“Harvest in dry weather as this is good time for quicker drying of tubers and healing of skin wounds. Wet soil makes harvesting difficult and may lead to tubers getting diseases.”


Irish potatoes take an average of 70 to 120 days to mature, depending on variety. According to Kariuki, an acre can produce an average of 7,700kg and a kilo of potatoes go for Sh27 according to NPCK. A farmer could earn Sh207,900 in three months. 

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