Yam Bean

A climbing vine with dainty soft purple flowers whose roots you can eat. It has a crunchy, sweet and refreshing taste that looks somewhat like an apple. It is usually eaten raw in salads but can also be cooked like a potato.  After harvesting the roots, they do not discolor and remain crisp for a long time.

Originating from Central America, they are now widely grown in many countries.  The roots can reach up to 20 kg in size while the vine can grow 4-5 m. However trimming the vine to a manageable size will still produce a good harvest. Similar to potatoes, any parts growing above soil level are toxic, so it’s important to avoid eating any parts that are growing above the soil level such as the leaves and seeds. If you see any parts of the tubers being exposed to the sun, cover them with soil similar to the process of growing potatoes.

Sow in Spring in temperate areas whereas tropical climates can sow all year. Sow 25mm directly in final position and the temperatures must reach 26-28°C to germinate. Soaking seeds overnight will improve germination and seedlings emerge in 6-10 days. It is frost-tender and requires 9 months without frost for a good harvest of large tubers. In cooler climates harvest the roots when the plant has died back.

It does not tolerate soggy soil, but it does require consistent watering’s that prevent the soil from drying out. Water the plant at the soil line rather than on the leaves. Ensure your  plants receive at least 5 cm of water per week to mature and produce healthy tubers.

Since the part of the plant used by humans is in the ground, it’s best to avoid high-nitrogen fertilizers that boost leaf and stem growth. Instead, encourage root growth by using a potassium-rich fertiliser about once per month during the growing season.

Do not let the plants go to seed; pinch the flowers for added root production. Deadheading flowers can significantly increase the root harvest, as this prevents the plants from expending valuable growing energy on flowers rather than roots.