Harsh conditions for outdoor growing

I want to plant 20-30 plants this spring. I have a good hidden spot, but i would like to ask a few questions to someone who have expirienced this. The climate in my region during the summer is not too sutable for growing. The temp are 90+ F, and sometimes rain can be absent for 2-3 weeks. The thing is that i cant visit the growing spot too often, maybe once-twice a month. I would like to know if anyone has growed in similar conditions, leaving the plants for 2-3 weeks without water. Thank you in advance. PS I forgot to write that it wont be planted in pots, so that would be advantage.

The temps are fine. The lack of water could be a problem.

I found a link with "Browndirtwarrior" a Guerilla, he digs holes which he places a large garbage bag, and fills them with soil mix. You can use 50/50 soil and soil mix to save you lugging all that dirt. The garbage bags retain water and blocks competing vegetation. Anyway here's the link.
http://www.youtube.com/user/brwndirtwarrior

He's on this forum. Browndirtwarrior a true idol. I would love to talk to him. A real inspiration to us all cannabis growers.