Mashua, the tuber nasturtium

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A climbing perennial from South America, mashua (Tropaeolum tuberosum) yields tubers eaten cooked or raw with a surprising chocolatey after-taste, plus peppery flowers and leaves for salads. Give it the light, well-draining soil it demands and a few specimens will crop enough for a whole family.

Certainly you’ve heard of climbing nasturtium that flows through flower beds in the garden, which you might have planted to lure aphids away from the vegetable patch. How about meeting its cousin, the tuber nasturtium?

This climbing perennial hails from South America, where it has been grown for generations for its one-of-a-kind tasty tubers. It is very resilient and contains many nutrients.

Note that roots aren’t everything: the rest of the plant, from leaf to flower, will definitely elicit glee from anyone tasting your new nasturtium-filled recipes!

Planting mashua

Mashua is a root crop, so well-draining and loose soil is always a plus.

Preparing the soil

In Fall, prepare your soil with a generous amount of soil amendments such as soil mix, sand for drainage and ashes for potassium nutrients.

Indeed, it’s important to note that tuber nasturtium grows best in light, well-draining soil types.

In Spring, just before planting, shuffle the soil around in the planting area, adding more compost or fully ripe manure.

Planting

At the beginning of Spring (late winter, early spring), plant the tubers in pots and keep these out of the cold. In late spring, when you’re sure it won’t freeze anymore, set stakes up every 20 inches (50 cm). These should be pretty sturdy, and at least 6 feet / 2m tall to fully support the plant during its vigorous growth.

Near each stake, transplant one of the young seedlings. For a better harvest, make sure your seedlings start off in full sun. Since mashua is a very productive plant, just a few specimens will do for the needs of a whole family.

Growing and care

It’s pretty easy to care for tuber nasturtium, and it won’t take much time. The main task is ridging, in the same manner as you would ridge potato and sweet potato plants. This will greatly increase the number and size of your tubers. Another point is to stay wary of dry spells, so you can water when the weather is too dry. Last note: no need to prune or trim mashua as it grows.

Diseases and pests

Mashua is more vulnerable to pests and parasites than it is to disease. Among the most common bugs that prey on the plant, you’ll find caterpillars and flea beetles (Epithrix spp.) which tend to devour stems and leaflets on sprouts and adult plants. Like all species of nasturtium, it is highly vulnerable to aphid attacks, especially the black aphid species).

Harvest and keeping

Harvest takes place in Autumn, when leaves have already died off. Unearth the tubers with a spading fork. This reduces the risk of damaging them.

A good thing to know is that it’s perfectly possible to simply keep the tubers in place in the ground, and only harvest them when you’re about to consume them. There is a chance, however, that rodents take a nibble at them in this case.

→ To avoid this problem: store your harvest in a dry sand silo or crate and keep it in the dark, away from light.

Cooking with mashua

It’s possible to prepare and cook mashua tubers in various manners:

• new leaves will thicken and spice up summer salads (pick them young or they’ll pack too much of a kick);
• flowers will decorate meals, they also have a peppery taste;
• the tubers, for their part, are edible both cooked and raw. You’ll be surprised at their chocolatey after-taste.

Roots can come in different colors, mainly because of minor genetic differences, but their nutritional value and taste are the same.

Which part of the mashua to eat, and when

Mashua is not only a root crop: leaves, flowers and tubers all reach the plate, each with its own flavour and its own moment. Here is what each part gives you.

Tuber colour varies from plant to plant, but taste and nutritional value stay the same.