By Umar Nsubuga
Propagating Irish potatoes is a process that requires careful selection and handling to ensure a healthy and productive crop.
Moses Kiptala from Mengya village in Kween district and Isaac Malinga from Kapchesombe, Kapchorwa district, have perfected the art of growing Irish potatoes by following specific propagation practices.
They share their knowledge and tips on how to achieve optimal results.
Understanding propagation in Irish potatoes
Propagation is essentially the breeding of new plants from a parent stock. For Irish potatoes, this means using seed tubers of whole potato pieces rather than seeds in the traditional sense.
According to Kiptala, “The quality of the seed tubers is the most critical factor for a successful yield.”
Healthy, disease-free seed tubers are vital, as they affect the vigor, growth rate, and productivity of the plants.
Irish potato tubers are sensitive to bacterial wilt and various viruses. To ensure the seed tubers are free from these diseases, Kiptala and Malinga both emphasise sourcing seed tubers from certified suppliers or seed farms.
These farms follow specific protocols to minimise the risk of disease. Planting infected tubers can spread diseases throughout the soil, reducing productivity and harming future crops.
Choosing the right seed tubers
Both farmers agree that selecting the correct size and quality of seed tubers is crucial for effective propagation.
Malinga explains, “The ideal tuber size for planting is between 40 to 80 grams.” Tubers within this weight range have enough stored nutrients to support healthy plant growth without being overly large or old.
Tubers that have been stored too long or have long, aged sprouts should be avoided. Kiptala notes,
“Old sprouts lead to low-vigor plants that struggle to establish themselves in the soil.”
He advises selecting tubers with fresh, healthy sprouts, as they’re more likely to produce strong, resilient plants.
A key step
Kiptala says Irish potatoes have a dormancy period during which they do not sprout. The length of dormancy varies by variety, and it’s essential to plant only tubers that have broken dormancy.
If tubers are planted too soon, they may not sprout properly, leading to poor crop establishment. Malinga says to break dormancy naturally, tubers can be stored in a well-ventilated, cool area with indirect light until small sprouts begin to emerge.
“Always check your seed tubers for sprouting before planting,” says Malinga.
Tubers that fail to sprout or are sluggish in sprouting may indicate low viability. Sprouting shows that the tuber is ready to grow and has the energy necessary for a strong start in the soil.
Planting without cutting the seed tubers
Both Kiptala and Malinga discourage cutting seed tubers before planting. Although cutting can yield more planting pieces from a single tuber, it greatly increases the risk of spreading bacterial wilt and other diseases.
“Cutting exposes the tuber to pathogens and may lead to rotting in the field,” Kiptala explains. Whole tubers have natural barriers against infections that are lost when cut.
Planting whole, intact tubers minimises disease transmission and reduces the risk of rot. This approach also supports uniform growth, as each plant receives the complete nutritional and genetic potential of a whole tuber, leading to healthier, more vigorous plants.
Proper planting techniques
To promote healthy growth, Kiptala and Malinga recommend planting seed tubers in well-drained soil that has been properly tilled and amended with compost or organic fertilizers.
Irish potatoes prefer a slightly acidic soil pH between 5.5 and 6.5. Planting should occur at the start of the rainy season to ensure adequate moisture for sprouting and early growth.
The seed tubers should be planted 10–15 cm deep and spaced about 30 cm apart within rows, with rows 60–75 cm apart to provide ample space for tuber development. This spacing also allows for easier movement between rows for weeding, hilling, and applying fertilisers or pesticides.
Maintaining optimal growing conditions
Once the tubers are planted, it’s essential to keep the soil moist but not waterlogged. Overwatering can lead to rot, while insufficient water can stunt growth, Kiptala explains.
“As the plants grow, earthing up (or hilling) should be done to cover any exposed tubers, as exposure to sunlight can cause greening, making them unsafe for consumption,” he says.
Applying mulch around the plants can also help retain soil moisture and control weeds.
Kiptala recommends mulching with straw or dried leaves, especially during dry spells, to protect the soil and reduce evaporation.
