sorry, no experience with mekong specifically. but i have grown other 100 percent sativa haze varieties. they are usually true breeders, and make great f1 crosses with other stuff. the one i grew took 16 weeks to flower, and with that being a cambodian variety i would give mekong probably about 18 weeks or so, (strains from that part of the world take infinity plus a day to finish!). it should have a real sativa get up and do stuff kind of high. hope this helps, happy growing!