i recently finished a diorama with a little river running through[ pics posted here]
i used live chives. to represent weed in the river.....I cut them too the desired length,
then dipped them in a white glue/water soloution...and dried em with a hair dryer...
then i painted them the appropriate colour ..another trick i use with live foliage..like mosses etc is to seal it airtight .. that is to encase it in a thin covering of clear casting resin, this process seems to preserve the plant/leaves /whatever..
like the mosquito in amber..from jurassic park...........