Canna can survive extreme heat

In correspondence on the International Canna Club site Dale McDonnell replied to a query about how her Cannas were faring in the extreme and exceptional heatwave being experienced in Australia. She wrote:

"The Cannas are just loving the heatwave Malcolm, as long as I keep the soil damp. I've had to hand water a few on the corners of beds where the sprinkler is hit or miss depending on the wind. The really dwarf cannas are struggling though. They just don't have the storage capacity in their rhizomes. 'Pink Sunburst' is just fine. In full sun all day. This is one tough little Canna. The tiddlers are receiving extra TLC., but Sunburst doesn't need any."

"Only watering all the cannas every third day, but giving them a thorough soaking each time. Virtually flood irrigating them with the sprinklers. It normally takes three days to get all the stock beds watered anyway. I just can't rotate the watering cycle any quicker as it depends on the pumping capacity of the big pressure pump. I can only run 7 big sprinklers at a time. Several of the tree lines are on a dripper system as are my silver birches."

C. 'America', taken at 6.30 am after a day of 46.7C, when the pic was taken it was still over 30C

"I have the rest of the place to keep alive and kicking including a small citrus orchard and another of peaches, plums and apricots. There's a vegie garden and beds and borders of other shrubs and stuff. The cannas can't hog all the water. We cannot begin the watering cycle until the sun is almost down or everything gets burnt."

"Canna flowers are not lasting very well and they crisp like brown paper when they are done. Even the self cleaners are looking messy. The flower collapses and wraps itself around the seed pod and dries there. Still, I have quite a good show of bloom and the foliage is looking magnificent. The various white cannas all look a mess and the blooms are spoiling before they open. Reds are much the same but the pinks, yellows and oranges seem almost impervious to the heat. Even very thin, textured, pale, pinks are looking great. It's a little weird to look at over 400 cannas and see hardly any sign of red in the beds. 'King Humbert' and 'America' are the only reds in flower and the foliage is holding its colour magnificently in both. So much for knocking the floppy Italians for transient blooms. 'Asia, 'Austria', 'Burbank', 'Wyoming', 'Africa' 'Italia', 'Roma', 'Tropicanna Gold, 'Durban', 'America' and another unidentified, dark foliaged burnt orange Italian, are all looking wonderful but 'Mrs. Kate Gray', 'Trinacria Variegata' and 'Britannia' are not flowering or even trying to flower. All the Crozy type reds are just burnt, brown pompoms on top of the stems and anything showing strong C. glauca influence is struggling - once again, the cause is skinny, small rhizomes under them."

C. 'Italia', photo taken same time as C. 'America', above

"Every time I give the old Wisteria a deep soaking it bursts into bloom again. So far this Summer it has flowered five times. Brugmansias in the shadehouse have dropped most of their leaves and just have tufts at the end of each branch. They are receiving ample water, but just can't hack the extreme heat. Still popping out the odd flower or two."

"The deciduous trees are shedding a lot of leaves also, to save transpiration, but they are okay, just looking sparser. The Silver Birches are really struggling despite nightly deep watering. Young trees purchased bare rooted, and only in the ground for 16 months. On the severely stressed trees we are leaving a sprinkler running very low all day. Partly for the trees and partly for the poor birds to gather under. Every patch of permanent shade has a dish of water for the birds too. It's too hot for them to even fly down to the irrigation channel 80 metres away. They are very distressed."

"The Quince plantation only receives a watering once a month and they are thriving and loaded with fruit. These are older trees and well established. Fig trees keep shedding their leaves and then trying to grow new ones which burn to a crisp despite deep soakings - again, they are young trees, so do not have extensive root systems yet. They are hanging on to their unripe fruit though. The roses have stopped blooming and shed leaves, but they will come back fast as soon as things cool down."

"It has been so hot that the fruit on my pair of cumquats has dessicated as if it has been in a food drying machine. I was going to offer an earthy description of them, but it might offend city folk. Just think shrunken, flabby, miniature, bull and ram appendages hanging all over the trees! I'm about to pick some tomorrow and let them plump up in the brandy bottle. The trees themselves are just fine."

"Still sizzling here. No relief for at least another week the weather boffins tell us. Sorry if this is more than you ever wanted to know about heatwave conditions."

Our thanks to Dale for such a detailed description, which adds considerably to our understanding of how our Cannas respond to the weather extremes. As a total contrast, the picture below shows the Canna beds at Hart Canna in England yesterday.