Posted: 28/04/2016 at 17:20
Perki, I would pot on all of those cannas to keep them growing fast. fresh compost will add feed too.
I would not be moving them from gh to imdoors now though....keep them in gh overnight and put outside during the day. All mine, including small divisions taken in autumn are all outside now.....milder here so wait a while for temps at night to increase a little where you are.
there are virusses that affect cannas and I think Pretoria is susceptible however I would not jump to conclusions. Proper variegation develops when plants are growing well.....e.g. Miscanthus grasses like zebrinus do not develop their gold bands until almost mid summer.
Encourage good growth and have patience I think
my cannas in the ground occupy several feet across with stems already quite tall