Dioscorea batatas - Chinese yam

The Chinese Yam, in Latin Dioscorea batatas, is one of the few representatives of this group of tropical plants that can adapt to outdoor cultivation in temperate latitudes. It is a perennial vine with a large tuberous root, which produces annual climbing stems adorned with beautiful heart-shaped leaves. Planted in good, rich, and deep soil, and in a warm location, the Chinese yam is a productive species, with giant tubers harvested from November to March, as needed, taking care to gently remove them, so as not to break them. The plant can easily be propagated by dividing the tubers or by planting the bulbils that form on the stems. It is a good plant for permaculture, and can be grown in an edible forest, for example.

Dioscorea batatas (Synonym D. polystachia) belongs to the Dioscoreaceae family and is native to Asia (China, Japan, Korea). This climbing plant is also classified as a root vegetable and is a staple in traditional Asian cuisine. Its above-ground vegetation regrows every spring and disappears in winter. The slender stems can climb up to 3 metres (10 feet) high on a trellis or around a supporting tree. Under favourable growing conditions (in a tropical climate), its tuberous roots can exceed 1 metre (3 feet) in length and weigh more than 30kg. Shaped like a club, they are covered with grey-brown skin with eyes like potatoes, and their flesh is pale yellow to almost white. In temperate areas, it is rare for them to exceed one kilogram. The tubers of the Chinese yam are rich in starch, with a sweet flavour, and can be consumed cooked or even raw. The foliage consists of entire leaves, arranged in an opposite manner on the stems, heart-shaped with a pointed tip, green and very glossy, with prominent parallel veins. The flowering, of little interest, takes the form of clusters of small pale yellow-green flowers, often sterile. Some years, they are followed by the formation of bulbils, which are also edible and easy to replant.

In terms of cooking: peel your tubers, cut them into pieces, and prepare them like potatoes, mashed, fried, chips, steamed, in salads, sautéed in a pan, gratin, in soups, or in vegetable medleys. The small tubers attached to the stems can be consumed like new potatoes. This plant is rich in vitamins B and C and minerals. The leaves and roots have recognised uses in Chinese medicine.

The Chinese yam can only be cultivated outdoors. Plant it with a sufficiently sturdy support due to the weight of the vegetation; the density of its foliage will also create a beautiful visual screen on a grid or trellis. To harvest, it will be necessary to wait 7 to 8 months after planting tuber sections or 21 to 22 months after planting bulbils. Harvest the bulbils in October and dig up the tubers from November to March.

Tips: mulch the soil in summer to maintain moisture and save on watering, and add well-decomposed compost in spring. Avoid planting other root vegetables before or after growing yams.