Roger is absolutely right. Relatively few Hedychiums are truly
deciduous and only appear to act like this when subjected to several
degrees of frost. I grow about 15 different species and hybrids in my
garden and growth is always fastest with better flowering when the
previous year's stems have been retained. Only cut the most ragged
and oldest stems - every bit of extra photosynthesis from retained
leaves will augment growth rates and abundance of flower. Even Cannas
are better for being allowed to retain most of their foliage although
I tend to chop mine back once the new shoots are about a foot or so
high - usually in March.

Dave Poole
TORQUAY UK