did you mean 80cm...i think thats what they meant...anyhow not sure what went wrong but if they are stretching like crazy you can tie em down by gently bending the top of the plants sideways...gradually the plant will adjust and u can continure to tie the top down about another inch (few cm.) further each day by pulling the string a little futher under the pot...will cause the plant to bush out tremendously and that top cola u tie down will get pretty big