Not visited VOF, but having experience of Western Himalayas, 20 july to 20th August is the most appropriate season for collecting majority of plants in Flower in the alpine region, including Valley of Flowers.
--
Dr. Gurcharan Singh
Retired Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.
Phone: 011-25518297 Mob: 9810359089
http://people.du.ac.in/~singhg45/