Canna edulis commonly known as Achira is a really easy to grow canna with big green banana like leaves and very attractive simple but really bright orange and yellow flowers which are produced in profusion throughout the summer. Capable of reaching over 2 metres high each season. Many of you will have noticed a clue in the name, Canna edulis, yes indeed it is very much edible. In wild Canna edulis grows in the foothills of the South American Andes were it has been cultivated for centuries as a source of carbohydrate, its rhizomatous roots being cooked and eaten much in the same way as you would use a potato. So one for the alternative allotment too, perfect for our changing climate and taste for the exotic.
Like most canna, Canna edulis does best and grows largest when planted outside in the ground. If you live in milder regions this canna can be left in the ground year round. Simply mulch around the base each autumn with a generous layer of organic compost, helping to protect the roots from penetrating frost. All growth above ground usually begins once the weather warms up in mid spring gathering pace until the last frosts have paced when you can almost watch them grow, the pace is that rapid. In Autumn or early Winter after the first heavy frost the foliage collapses. This is the time to trim back the stems to 20cm or so and add the protective layer of mulch. Alternatively if you wish cannas will happily grow in containers with regular repotting if you want large specimens. The containers can be brought into a cool frost free location during the cold winter months, if you have space they can even be brought into cool conservatories before the frosts where they will continue to grow through winter.
Whatever you decide to do with your canna it’s worth considering that such rapid and lush growth needs to be sustained with rich feeds for maximum benefit. As previously stated an organic mulch in the Autumn is beneficial to adding nutrients to the soil bu I like add go further than this by adding composted farmyard manure to my canna beds in spring plus top up drenches of liquid seaweed feed. Especially important for container grown plants. I’m biased towards organic feeds where possible but the choice is yours.