Feed me, feed me
At present I only have a few canna cultivars. As covered in some recent messages, I am fearful of contracting virus – well I am fearful of buying canna stock that is infected and will spread virus to my existing plants. So most of my plants are ‘Lon01’ (Tropicanna ®), the same plant as ‘Durban’. I find it easy and vigorous and it does all you would want of a canna; bright flowers, tall growth and spectacular leaves.
I dig up most of the plants in autumn and overwinter them in just frost-free conditions, just ‘ticking over’ and not quite dry. Then I divide and pot them in spring and start them into growth. Because I do not damage the rhizomes in autumn, by cutting or splitting them, winter rot is kept to a minimum. I also have some plants that are left in the ground and, so far, they have survived winters but they do come into growth a bit later and take some time to reach anything like flowering size.
I have been spreading it about this spring, and everyone who has had a potful has received the same advice ‘water and feed as much as possible’. Cannas are tolerant of wet soil and many are used as water plants in warmer areas. In the garden they really respond to humus-rich, moist soil and plenty of feeding. Because I tend not to water the garden borders unless plants are in real danger – usually just soon after planting – the cannas in borders look different to those in pots. In pots they are planted in lovely multipurpose compost with added controlled-release fertiliser and fed and watered liberally.
I gave my last spare pot to a garden visitor last week, after they saw some plants in a bed, and they were startled by the growth on plants in a large pot, with some white (‘Casablanca’) lilies. I explained that these were the same plants, divided and initially potted from the same overwintered clumps. The only difference was that the plant donated needed planting out and more feeding, hence the 30cm height, compared with the 1m or so in the large pot.
I often get sent questions about why cannas have not flowered and these are usually accompanied by photos of stunted, starved plants in 30cm diameter plastic pots. The plants were put in three years ago and have survived winter because of neglect and the fact that they were dry and the pots are filled with crowded rhizomes. If divided in spring, replanted in good compost and fed they would look amazing again. The only problem is that you get more and more plants every year. Local garden centres are selling pots of Tropicanna ® for €20 – €30 a pop and it is nice to know I have a small fortune in the garden, in theory.
Cannas in some beds in the garden, planted in May, will eventually make some decent growth but could do with some irrigation. Combined with pelargonium ‘A Happy Thought’ and double nasturtiums.
Their lucky brother was put in a pot and fed and watered and is already looking lush and doing what cannas do best. I am hoping they will be as tall as the lilies by the time they bloom for a big contrast.
The Biking Gardener 
Virus seems to be everywhere! Because Canna are so prolific, there is rarely any reason to purchase any. However, I did, on three occasions, and only one of the three acquisitions was without virus. Because some of the landscapes are separated by miles, some of the original and new unvirused Canna are safe. However, the majority can no longer be shared with friends and neighbors because they are either infected or possibly infected.
‘Durban’/’Tropicana’ is the one in biggest number here and it becomes a challenge to figure out what to do with all the plants. ‘Cleopatra’ has built up very well in numbers also and is a good performer. ‘Panache’ is first to flower this year and was left in the ground over the winter. We leave some in large pots and outside over the winter. Others are stored in a glasshouse and planted out in the ground after frost has passed. ‘Durban’ with Kniphofia ‘Bee’s Lemon’ is a nice combination at the moment.
The kniphofia/canna combo sounds good. I have been pleasantly surprised at how well the cannas have overwintered in the ground. I have a clump of the water canna ‘Ra’ that I left out by accident (in the ground, not the pond) by accident and it is growing again.