Back in the day, we used colchicine to make tetraploid orchids by carefully exposing developing protocorms while still in the flask. A real pain because you can't sterilize it in the autoclave (the colchicine breaks down). Now the weapon of choice is minute concentrations of oryzalin, which as many gardeners know, is a dirt-cheap preemergent herbicide. It's less toxic than colchicine and you can get it at the farmer's co-op. The only downside is that it is VERY orange, so don't spill it on yourself or anything else or you'll have orange hands for a while. Bob Zone 7 _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>