Deadheading
cannas can be performed quite easily depending upon what the grower wants to
achieve. Keep in mind most cultivars will produce multiple bloom clusters per
stalk (2 to 4 typically). The first cluster of blooms are produced on the tip
of the main stalk but as this cluster blooms it should not be removed until the
main stalk begins to grow and produce the next blooming cluster.

In other
words the blooms are actually attached to the main (primary) stalk via a short
secondary stalk. Remove only the short secondary stalk where it attaches to the
main (primary) stalk. Do not cut the primary stalk until all bloom clusters are
produced. Depending on your location and plant density you may never need to
cut the main stalk until early winter.

Keep in mind
that no seed pods or seeds (when applicable) will be produced.

Below is a somewhat
helpful youtube video if you only pay attention to where she removes the flower
head and you will see the next bloom head remains.

I am not
sure who titles these things.

https://www.youtube.com/watch?v=oEhVGEvQma0

Kent

Once the bloom cluster has finished, I sort of pinch around it to see if there is another coming next to it. If there is, then I only cut the spent bloom cluster like she did in that video. If there is no other cluster coming, I cut that stalk around the closest set of leaves down the stalk.