Three years ago I planted a Meidiland bush at a corner of a bed, the rest being occupied mostly by iris and daylilies. It has really thrived, in fact now its canes cover the whole bed! I need to cut back the canes drastically so that I can work in the bed, and I do not care if I inhibit flowering this year. However, I do not want to kill the bush by inducing growth too early. How soon can I prune it? I live on the border between zones 7 and 8; it is rare that we get any lows lower than 10F and if so they are only for one or two nghts a winter.