Trust me... They need water. If the natural plants in the area are lush, and tropical in nature, you could maybe get away with out water as marijuana plants can develop a very large root system if given the space.. If they are lucky, they may find their own water supply, but it's a gamble...

If the area you plan to plant the seeds in is dry and deserty, the chances are slim that the plant will find it's own underground water supply. I wouldn't take the chance if it were me..

My advise would be: don't waste the seeds, rather give them to a friend to grow. He will share the crop with you, no doubt :>