Best fertilizer suggestions , thanks
If you are growing in the U.S. I believe this cultivar was/is sold under the name of Canna Yellow King Humbert (Horn Cannas). This cultivar was first introduced from Europe in the early 1900Ã¢ÂÂs and was classified with the Italian group of cultivars. This particular group consists of hybrid crosses that produce very large flowers but the plants are triploids (genetics-sterile) due to the breeding.
The valid name for the cultivar is likely either Canna Roma or Canna Italia; there seems to be some question among the experts.
Your plants look excellent at this time and you can always supplement the feeding with a general granular or liquid fertilizer. I would suggest you thin out your bed to prevent the overcrowding. You need to consider posting your location. That is often an important factor.
Thanks for the tips Ken !
PS I am in SW Florida
Cannas are gross feeders - they love deep rich compost, seaweed, horse manure etc. I live on the ocean so my daily ritual is grab a bucket and walk the beach picking up seaweed, dead fish etc. Throw it all in a wheeley bin, fill it with water and leave for a couple of weeks to break down - then once every two or three weeks each canna plant - plus everything else in my garden gets a bucket of liquid under the foliage on the soil base - best fertilizer ever.