This year I tried my hand at growing some mashua (Tropaeolum tuberosum). It's grown widely in the Andes as a root crop. I first saw it growing in Martin Crawford's garden at the ART and was struck by how lush it looked in Devon. I wasn't sure how it would do in Wiltshire, but thought I would give it a try.
I bought two tubers and planted one either side of the Morello cherry. I put in a bamboo cane next to each so that it could climb up into the canopy of the cherry. It started off fairly slowly with a couple of shoots tentatively climbing up the pole in April.
Not long after I netted the cherry tree to save the crop from the birds. Last year I just draped the netting over the tree but it wasn't very successful because although it was held up by the woody parts of the tree it made the new growth curl around. This year I thought I had a neat solution by making a lightweight frame from 8' bamboo canes lashed together to hold the netting up.
The frame worked well but I didn't anticipate how well the mashua plants would do. By the end of the summer they had reached right to the top of the frame and covered two sides of it and most of the top. The weight of the foliage was too much for my flimsy frame and pulled down one corner squashing the cherry for the second year in a row!
Mashua (Tropaeolum tuberosum) climbing over small netted Morello cherry (05 Nov 2011)
I thought about trying to remove the mashua from the netting but it was hopelessly tangled by then so I decided to leave it until the cold weather causes it to die back. If I net the cherry next year I'll have to invest in something more robust.
The plant is still thriving at the beginning of November giving a supply of tasty edible leaves which are not too different from its relative the garden nasturtium (Tropaeolum majus), which is also still growing in the garden but starting to die back from the cold now. Mashua is renowned for being pest and disease resistance. The video below shows how it is thriving despite acting as a route for the snails to come and feed on the shedding leaves of the cherry tree beneath it.
The video also shows how the water collects on the leaves just like nasturtiums. It makes for a spectacular sight after the rain when the plant is full grown.
Mashua (Tropaeolum tuberosum) leaves after rain showing superhydrophobic surface (05 Nov 2011)
The plant also started to flower a few weeks ago and is now covered in beautiful small orange lamp shaped flowers. Both of the plants are covered in them now.
Mashua (Tropaeolum tuberosum) flower (05 Nov 2011)
I haven't looked to see how big the yield of tubers is yet. Apparently there can be up to 4 kg per plant and they can be left in the ground until required. They have a high protein content and are a staple crop in the Andes. They are reported to have an anti-aphrodisiac property, reducing testosterone production although not affecting fertility! There is a good source of more information here
I'm not sure whether they can be treated like artichokes with some tubers left in the ground for next year in a wet UK climate. I'll probably leave some in as an experiment and keep some in storage just in case.