Canna, Canna edulis, also known as Achira and Queensland arrowroot, is a highly productive, hardy, perennial food source. The rhizomes are the main food product, however, immature seeds and young growing shoots may also be harvested for consumption. Canna grows six to eight feet tall and produces abundant flowers and leaves. The rhizomes are high in starch content, yet are easily digestible. This plant is closely related to ornamental canna plants; however, this plant has been domesticated as a food source for its starchy roots for thousands of years. Canna thrives in poor soils and waterlogged conditions and rhizomes can live underground for years without becoming too woody or inedible. This is the perfect sow-it-and-forget-it plant; leave it in the ground and dig as you desire a starchy food in times of need. Not to mention this plant is highly ornamental!
Canna is typically grown from root division: digging and splitting of rhizomes and replanting in new locations. Make sure propagation material has at least two buds for new growth.
This particular variety does grow true from seed, however, not all varieties do, especially where cross-pollination with ornamental varieties can occur. Scarification is commonly used to speed seed germination.
Canna is a carefree plant. It will grow in light shade or full sun. Canna may be used as a mulch source and likes to be regularly pruned to remove exhausted or older growth.
Harvest of rhizomes may begin as early as four months from root division. Ideal harvest time is six to ten months after planting.
Young tender shoot tips may be consumed as a vegetable.
Rhizomes are cooked and consumed like a potato, typically boiled or baked. A traditional method for preparation is to bake them underground whole for 12 hours, then scoop out the insides and consume. The starch may be extracted to make a flour to use as a thickener. Some Asian cultures even make clear noodles with the flour.
Where to obtain planting materials
I’ve only met one other person growing this plant intentionally on our island. I have seen this plant one other time on a hike to a Puna beach. Besides that, I’ve only seen the ornamental varieties around. Try an internet search, or ask around to see if it’s more commonly grown in your area.
I looked for this plant for a long time; I finally stumbled upon it while working at a friend’s farm. He has many varieties of canna growing. One day, I asked him about this one colorful canna plant. He said, “that’s achira from the Andes!” Little did he know I’ve been searching for this particular species for years! He said he only had one plant and I could take some seeds to propagate it. Luckily, it was in a lone location in his agroforest so it wasn’t cross-pollinated with any other species. I took my few seeds and started a tray of them. Within a few weeks’ time, I had 32 little keiki awaiting a spot in the ground! I eagerly planted them out at two different sites and feeling the need to spread these hard to find genetics I gave some away to some trusted gardener friends. At this point, I’ve collected so many of the seeds from my plants that I don’t even know what to do with them! I will continue to plant them throughout my agroforest in the wettest locations where some other plants don’t want to grow so I can create patches of food insurance for later. My friend’s farm is located in a fairly dry environment; once I took those seeds and planted them in a wet location, they became extremely prolific!