Tropaeolum, commonly known as Nasturtium, literally “nose-twister” or “nose-tweaker”, contains roughly 80 species. They are native to south and central America.
These fit neatly into three categories of a permaculture guild: herbaceous, rhizosphere and vines/vertical. Most organic gardeners know that nasturtiums are an all around useful flower in the garden.
Nasturtiums are considered a “pest trap,” because they attract aphids and other pests. They repel a great many cucurbit pests, like squash bugs, cucumber beetles, and several caterpillars. They have a similar range of benefits for brassica plants, especially broccoli and cauliflower. They are a trap crop against black fly aphids. They also attract beneficial predatory insects, hummingbirds and beneficial insects. They’re easy to grow in poor soil. They can be grown around the borders of an orchard (or garden), or within a tree dripline.
Nasturtiums are usually annuals, but some varieties are perennial, depending on the climate and species. They produce seeds and tubers and can be self-seeding annuals. You can also collect the seed for the following year’s crop.The most desirable perennial grown by permaculturists is known as Mashua, Tropaeolum tuberosum, sometimes known as “Ken Aslet”, a perennial in the nasturtium family. It has extraordinary resistance to insect, nematode and bacterial pests. It is grown as a companion plant to potatoes and any of the nightshade family. Some people allow it to grow up the trunk of their fruit trees.
Mashua is resistant to many insects, nematodes, fungi and other pathogens. It is also resistant to the Andean weevil which attacks potatoes and other tuber crops, and is used in companion planting for that purpose. This disease resistance makes mashua a valuable crop to intercrop with other cultivated species as an efficient and cost effective way to control pests and diseases without using costly chemicals. In the Peruvian highlands, mashua is often grown with maize, oca, ulluco, potatoes, legumes and grains. Mashua contains high levels of compounds with insecticidal properties (from Southern Illinois University, Mashua By Travis A. Clark).
Mashua contains many other medicinal qualities, found at the above article link.
Nasturtiums are in the Brassicaceae (cabbage family), the leaves and flowers are edible for humans. The flowers and leaves taste spicy and can add beauty and spice to any salad. The leaves can be dehydrated for winter use. They crumble readily and can be added dry or fresh in salad dressing, omelets, stir fry, or any number of dishes. The unripe seed and/or flower buds can be eaten like capers too!
Edible watercress, Nasturtium officinale, is believed to be in the Tropaeolum family but recent findings are that it is not.
One mashua plant can produce up to 9 lb. (4 kg) of tubers. The part of mashua that is commonly eaten is the tuber, and is one of the four most principal crops in parts of South America for that purpose. It can be eaten raw and is peppery. But when cooked, the peppery taste dissipates. All parts of Mashua can also be eaten (flower, leaves, seeds) like other nasturtiums.
Mashua has medicinal qualities, but curiously I found too many articles stating that it’s an aphrodisiac when it’s not (where did they get that information?). Folklore is that it reduces male fertility. There has been a scientific study verifying this, that showed a reduction in sperm count in rats, but not in levels of testosterone. The study: (Mashua) reduces testicular function: effect of different treatment times
Mashua is hardy in zones to 7b, but in cooler zones, can be heavily mulched or dug and brought indoors. It can be left in the ground and harvested in winter, in warmer regions, yet it’s one of the most frost tolerant of the varieties.
It was difficult for me to find a source in the US (but there are easy to find sources in the UK). Outside South America, the most common sources come from the US Pacific Northwest and New Zealand, principally because it’s now being grown experimentally in those places.
Fry Road Nursery (Oregon)
Far Reaches Farm (Washington)
The Occidental Arts & Ecology Center (California) (note: they appear to sell only at local plant sales, but it’s worth checking)
Whether one uses the mashua or other varieties, nasturtiums are beneficial to plant in each garden bed that has either brassica or nightshade crops. They are equally important for fruit orchards as a pest trap.