Tropaeolum tuberosum Ken Aslet

Tropaeolum tuberosum Ken Aslet is a variety of tuberous nasturtium that is more vigorous than the type species, with a delightful flowering period from July to September. Its flowers are like delicate yellow-orange bells that appear to be hanging from foliage garlands of a slightly bluish-grey green. These stems are capable of quickly and gracefully winding around their support, transforming even the most modest trellis into a flowering mantle. This charming climbing plant is able to grow in poor soils but its fleshy root, much appreciated in cooking, dislikes the cold dampness of northern hemisphere winters. For all these reasons, it is a great addition to both ornamental gardens and vegetable patches, requiring care similar to that of a Dahlia.

Tropaeolum tuberosum, like all nasturtiums, belongs to the Tropaeolaceae family. This vigorous plant, perennial by its tuber, is native to the Andes, where it can grow at high altitudes, even in poor soils among weeds. This entirely edible botanical species still constitutes one of the main food resources for some Andean populations, who cultivate it on the Peruvian and Bolivian high plateaus. Like potatoes, it forms tubers that multiply rapidly and are arranged in a string. These fleshy roots, shaped like elongated pears, measuring 5 to 15 cm (2 to 6in) in length, pearly and of a light yellow colour streaked with purple, produce woody climbing stems that can reach up to 2.5 metres (8 feet) under good conditions. They are adorned with typical nasturtium foliage: carried on a red central petiole, rounded and divided into 5 lobes, the leaves are a bluish-greyish green, fairly light, with fine lighter veins. Flowering begins in July and usually ends in September-October. The tubular flowers, 4 to 6 cm (2in) long, surrounded by a red-orange calyx with a spur, open into very bright yellow corollas. They are suspended from long red peduncles in the axils of the leaves, all along the stems.

The tuberous nasturtium Ken Aslet is not a very hardy plant, especially if the soil is moist in winter, so it should be dug up and stored at the first frost, like a Dahlia. In the garden, allow it to take over a trellis, which it will cover in just one season. Alternatively, let it cover the ground if you have enough space: the result will be astonishing and charming at the same time. With its moderate growth, occupying about 2 metres (7 feet) in all directions, it is perfect for adorning a trellis in an original way. It can be paired with a Sollya heterophylla, with its azure blue bells, or with sweet peas or morning glories. By planting the wild tuberous nasturtium (Tropaeolum tuberosum) alongside it, which flowers later, you can enjoy uninterrupted flowering until the first frost in mild climates. You can also grow it in a pot, from which it will elegantly cascade its leaves and flowers.

In the vegetable garden, space the plants about 1 metre (3 feet) apart in all directions and install a support for the stems to climb on. In this nasturtium, everything is edible: its young leaves and flowers can be consumed raw in salads (or the leaves cooked as a green vegetable). The tubers, when raw, have a pungent flavour that pairs well with other raw vegetables (cabbage, beetroot, celery, cucumbers), which can be accompanied by some walnut kernels and cubes of cheese (feta, goat, comté). This pungent aspect disappears when cooked, giving way to a very mild, round, aromatic flavour that evokes violets, pepper or licorice, depending on one's palate. These roots can be prepared like potatoes: boiled or steamed with their skin, served with butter or cream, parsley or in a vinaigrette sauce, or thinly sliced and sautéed in a pan, for example. In Bolivia, they are prepared as a compote and sweetened with molasses.