Crop details

Irish potato (viazi mviringo)

Solanum tuberosum

Family: Solanaceae

Quick stats

Family	Solanaceae
Typical harvest	18.7 t/ha
Varieties	3
Pests & diseases	6
Seasons	3

Crop profile

Growth habit	annual
Days to harvest	110
Main uses	Boiled, fried, mashed and roasted potatoes, crisps, chips and animal feed from rejected tubers.
Pollination	self
Origin / where it grows	Irish potato (viazi mviringo) is mainly grown in cool highland and upper mid-altitude areas with good rainfall or irrigation.

Weather, soil & spacing

Best temperature	15–20 °C
Rainfall	600–900 mm/yr
Altitude	1500–3000 m
Best pH	5.5–6.5
Soil type	Deep, loose, well-drained loam or sandy loam with plenty of organic matter. Irish potato (viazi mviringo) forms better tubers in friable soils.
Row spacing	75 cm
Plant spacing	30 cm
Planting depth	10 cm
Seed rate	2000 kg/ha
Nursery days	—

Simple notes for farmers

About the crop: This crop is annual. You plant, grow and harvest it in one main season, then plant again. You can normally start harvesting about 110 days after planting, depending on care and variety.

Main use: Farmers mostly grow this crop for boiled, fried, mashed and roasted potatoes, crisps, chips and animal feed from rejected tubers..

Pollination: This crop is mainly pollinated by self. Keeping flowers healthy and having insects like bees in the field helps improve fruit set and yields.

Where it grows: Irish potato (viazi mviringo) is mainly grown in cool highland and upper mid-altitude areas with good rainfall or irrigation. It is grouped under: Roots & Tubers.

Best climate: This crop does well in warm areas where the temperature is usually between 15 and 20 degrees Celsius. It prefers places that receive around 600 to 900 millimetres of rain in a year. It can grow from near sea level up to about 3000 metres above sea level.

Soil: The crop grows best in slightly acidic to near neutral soils, with a pH of about 5.5 to 6.5. It does well in deep, loose, well-drained loam or sandy loam with plenty of organic matter. irish potato (viazi mviringo) forms better tubers in friable soils.. Good drainage is important, so avoid waterlogged spots.

Plant spacing: Plant in rows about 75 centimetres apart, and leave about 30 centimetres between plants in the row. This gives each plant enough space for roots and canopy to spread.

Planting depth: Dig planting holes or furrows about 10 centimetres deep so the roots sit firmly in the soil but are not buried too deep.

Seed or planting material: Use around 2000 kilograms of seed or planting material per hectare. Spread or plant evenly so the field has a good stand without being overcrowded.

Farmer guide (mwongozo wa mkulima)

Planting: Use clean, certified or healthy seed tubers about the size of an egg. Plant Irish potato (viazi mviringo) on ridges when the soil is moist, placing tubers with the eyes up and covering with 5–10 cm of soil.

Transplanting: Planted directly as seed tubers; not transplanted from a nursery.

Irrigation: Keep soil evenly moist from emergence to flowering and early tuber bulking. Avoid long dry spells or heavy waterlogging, which reduces yield and quality.

Fertigation: Where drip or sprinkler is available, split N and K into several small applications. Potatoes respond well to balanced NPK but too much nitrogen delays maturity and lowers dry matter.

Pest scouting: Inspect fields weekly for late blight, early blight, aphids, potato tuber moth and leaf miners. Focus on lower leaves, stems and the soil around the base of plants.

Pruning: No pruning needed; earthing up (heaping soil around stems) helps protect tubers from light and pests.

Harvest: For ware potatoes, harvest when most leaves have yellowed and dried and skins are firm (do not peel off easily when rubbed). For seed, harvest a bit earlier and handle gently.

Postharvest: Lift Irish potato (viazi mviringo) gently to avoid bruises. Cure in a dark, well-ventilated place for about 10–14 days, then store in cool, dark conditions away from light to avoid greening.

Nutrient schedule (mbolea kwa hatua)

#	Stage	DAP	Product	Rate	Targets (kg/ha)	Notes
1	Basal at planting	0	NPK 17-17-17 or 15-15-15	300 kg/ha	N: 51, P₂O₅: 51, K₂O: 51	Apply in the furrow and lightly mix with soil before placing seed tubers.
2	Topdress and earthing up	30	CAN 26% N + MOP (muriate of potash)	200 kg/ha combined	N: 40, P₂O₅: 0, K₂O: 40	Apply along rows before earthing up Irish potato (viazi mviringo) plants.

Nutrient requirements

Nutrient	Stage	Amount	Unit
N	Basal	60	kg/ha
P₂O₅	Basal	60	kg/ha
K₂O	Basal	80	kg/ha
N	Topdress_early	40	kg/ha
P₂O₅	Topdress_early	0	kg/ha
K₂O	Topdress_early	40	kg/ha

Name	Country	Maturity	Traits
Shangi	KE	90	Very popular, early bulking, good for chips and boiling but shorter storage life.
Tigoni type	KE	110	Good yield, suitable for boiling and mashing, moderate dry matter.
Local viazi mviringo landrace	KE	120	Traditional taste and adaptation; lower yield than improved varieties.

Stage	Product	Rate (kg/ha)	Notes
Basal	NPK 17-17-17 or 15-15-15	300	Provides balanced nutrients for early Irish potato (viazi mviringo) growth.
Topdress (N source)	CAN 26% N	150	Used at first earthing up on moist soil.
Topdress (K source)	Muriate of potash (MOP)	100	Supports tuber bulking and quality, especially in K-deficient soils.
Organic	Well-rotted farmyard manure	8000	Improves soil structure and water holding; apply before final land preparation.

Name	Type	Symptoms	Management
Late blight	disease	Dark, water-soaked patches on leaves and stems of Irish potato (viazi mviringo), with white mould at edges in wet weathe...	Use resistant varieties where available, spray protectant and systemic fungicides as recommended and destroy infected cr...
Early blight	disease	Brown spots with concentric rings on older leaves, leading to early defoliation.	Maintain good nutrition, especially nitrogen and potassium, and use fungicides where disease pressure is high.
Potato tuber moth	pest	Tunnels in stems and tubers, with frass and webbing. Damage worsens in store.	Earth up well to cover tubers, avoid cracked ridges and use fine mesh or covers in stores.
Aphids	pest	Clusters of small insects on stems and leaf undersides, sticky honeydew and curled leaves; important virus vectors.	Use healthy seed, monitor often and control high aphid populations early.
Bacterial wilt	disease	Sudden wilting of Irish potato (viazi mviringo) plants without yellowing; brown ooze from cut stems and tuber rings.	Use clean seed, avoid planting in infested fields and rotate for several years with non-solanaceous crops.
Common scab	disease	Rough, corky spots and scabs on potato tuber skin.	Avoid very dry conditions at tuber initiation and keep soil slightly acidic (pH around 5.5–6.0).

System	Typical	Min	Max	Notes
Smallholder rainfed (low input)	8	5	12	Local seed, limited fertilizer and basic disease control.
Smallholder rainfed (improved management)	18	12	25	Clean seed, recommended fertilizer and regular blight control.
High input / irrigated	30	20	40	High-yield varieties, fertile soils, irrigation and full spray programme.

Country	Region	Planting	Harvest
KE	Highland main season (long rains)	Mar–Apr	Jul–Sep
KE	Highland short-rains season	Oct–Nov	Feb–Mar
TZ	Northern and southern highlands	Apr–May	Aug–Oct

Country	Region	Suitability
KE	Central and Rift Valley highlands	High
KE	Highland parts of western Kenya	High
KE	Hot lowland areas	Low
TZ	Northern and southern highland potato zones	High
UG	South-western and Mt Elgon highlands	High