Thursday, 27 December 2007

Canna toughies

Use herbicide in tank sprayer to tame wayward canna lilies
Oakland Tribune, Aug 23, 2003

Q. I removed a patch of canna lilies that was growing out of control. I was surprised to find that some rhizomes went down 2½ feet (95cm). My problem now is that I didn't get rid of all of them. They are starting to shoot up between the newly planted plants. The only thing I could find on the Internet to control the tubers was to burn them. Obviously, that is not an option. Any suggestion on an herbicide I can use?

A. Canna lilies can be a nuisance as they are hard to keep contained in one location. This is true of all types of rhizoming plants. All it takes is a little piece left behind to perpetuate the plant.

For your situation, Roundup is the ideal herbicide to use. The leaves and not the roots absorb Roundup, so it can be applied carefully around other plants without harming them. Protect the desirable plants with a cardboard plant shield. You could surround each plant with a shield or the unwanted canna shoots. Personally, I would isolate the unwanted shoots, apply Roundup, then move the shield to the next cluster.

I suggest using a tank sprayer to apply the herbicide instead of a hose end sprayer. It is easier to concentrate the spray in a single spot and the spray drift is minimized. You'll have to be persistent as it's a battle of attrition, but you should win it.

Some of the larger specimens can be vigorous growers
Malcolm's comments:
In case you have not read it, here is a quote from one of the funniest, tounge in cheek, articles I have encountered about Cannas:

"Ridiculously easy to grow, cannas will take root if dropped on sand, soil, asphalt, cement or slag heaps of radioactive waste. Before the arrival of the dumpster, towns had back alleys where garbage was hidden from view. Cannas grew so thick that people assumed the flowers appearance was a government beautification project. What convinced them otherwise was that the cannas throve - which they would not have had it been a government project. The truth is that these back alley orphans grew from roots discarded by gardeners who had exhausted other disposal methods like napalm, burial at sea and encasement in cement."

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