The Backyard Larder

A place to explore and buy perennial vegetables and other food plants.

Potentially Perennial Tubers

To my mind, ‘replant perennials’, such as the potato, where the perennating tubers are generally replanted in spring because they might not survive the cold of a British winter, don’t quite cut it as perennial vegetables. They almost do, as planting tubers in spring is still a lot easier than sowing seeds and nurturing far more vulnerable seedlings to maturity. But for simplicity’s sake I’d prefer to harvest roots, tubers and bulbs and replant a few straightaway for next year’s harvest. The various South American tubers like oca, mashua, ulluco and yacon are treated as replant perennials in most of the UK. I’ve been interested to see if planting them extra deep for extra protection in autumn might work.

I tried this with a yacon rhizome in 2014. Nothing emerged the following year. Yacon propagation rhizomes probably need to be fairly near the surface in order to grow successfully in the spring. It might be possible in a light soil and a thick insulating mulch under the shelter of a south facing wall – but these aren’t conditions I can provide at present.

Mashua was more successful, surviving this year and last. From what I’ve read it is rather more frost-hardy than the others. A shame therefore that its tubers tend to be the least popular for eating. We’re not sure if we like it ourselves yet (need to try some more cooking methods!) but it is beautiful and does have edible leaves, flowers and seeds like its relative the nasturtium.

Mashua plant
Mashua

I didn’t have any ulluco tubers to experiment with last year but I did have lots of tiny oca tubers to spare. So one day last winter I pushed them deep into the soil in the perennial kale bed. They were quite closely spaced and planted in a place where they would be quite overshadowed in the summer and have to compete with the hungry kale – but they were really just there for ground cover purposes (and with the overwintering experiment in mind). Oca leaves are edible too and taste of sorrel.

The oca came up fine in May and managed to avoid being hit by a late frost. They formed a fairly decent canopy over the bed. I dug up some tubers today – they were small but can be added to salads. Of course it was a particularly mild winter so I mean to try this again – and in a fertile bed in the sun next time.

Mashua and oca tubers
Mashua and oca tubers

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