acanthus white water advice needed plz

hi,ive just ordered 3 acanthus white water plants,the info that comes with them is to plant them up into 9cm pots and then plant out in 4 weeks..does anybody have any idea on their growth rate? would i be better planting them up into containers(til next spring) in 4 week not sure if they flower this yr or next or how fast they get established not much info on google.
julie x

 

Thanks armandii i will plant them in the ground then ive planted the mollis i grew from seed last yr and they havnt done much on growth height yet,im hoping they are making good roots thou..maybe i planted them 6 week early but i wasnt to know xx