An amazing range of cannas is available to gardeners, from dwarf types to those that tower 2m high. Cannas in pots are perfect for adding a tropical look to gardens and I find that they are increasingly winter-hardy.
In free-draining soils in sheltered spots, cannas can survive winter with a little protection but, to be on the safe side, it’s best to lift and pot prized plants after the first frosts.
Over the past couple of winters I’ve left a number of cannas outside with a simple pile of woodchip over the roots as protection and I’ve been pleasantly surprised at the resilience and large size of the clumps now. They have great drought-tolerance, too.
These tropical plants give gardens a lift in the late season when many other plants are starting to look a little haggard from the hot, dry summer. Cannas respond well to being grown in pots as they’re very hungry during the growing season.
They can be grown in any container with a drainage hole and do well in any peat-free compost. I find that they’re happiest in a large pot (so don’t let them become too restricted), as this encourages lots of lush foliage, which is the main reason for growing most of them.
How to grow cannas
Keep cannas moist until the end of September and feed once a week with a seaweed-based liquid fertiliser to encourage a good-sized plant. After the first frosts, when the foliage has been blackened (which triggers dormancy in the plant), pop them into a frost-free, dark place for winter and don’t water.
Repot the rhizomes into fresh compost in spring when new growth emerges. Water lightly to begin with and increase the amount as the plant gathers momentum; the bigger the plant, the more water it can process. There’s often plenty of growth in the pot to divide them at this stage, too. You only need plant a small division back in the pot as cannas grow quickly. Cannas can go outside at the end of May when the risk of frost has passed.
Try some in the border, too. If you have free-draining soil and a sheltered spot then, covered with a good barrow of mulch in the autumn, there’s no reason why they shouldn’t go through the winter in situ. They’ll still need plenty of moisture and feeding to get the best results though.
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