polymers for outdoors are bomb, i've dug 20 holes so far and all of them have polymers in them.
sometimes they are the difference between a harvest and no harvest/ crappy harvest....if ya don't know now ya know.
ask some of my buddies last season that were to cheap to buy some polymers how their harvest was during our hot ass drought last season. it's pretty nice to go see their plants and they are yellow and crisp...get paranoid about yours so u go take a peek and they are lucious and green. not nice for them but nice for me....not to mention the 1 lb per plant i was pullin in when theirs was dead.
http://www.watercrystals.com/Tested&Approved.htm
Warmer climates obviously need more watering but if you can find annual plants/weeds that are growing with drought then I would plant your plants beside these as they apparently get enough water.
there are indeed few indigenous annual weeds/grasses capable of growing in such a dry conditions. it's intersting all these plants have specific root system consisting of single tap root going straight down with very few side roots. really deep. usually this root will be much much bigger than what grows above the ground. cannabis root system is nothing like that. 6' tall ganja bush water request cannot be compared to tiny weeds that grow here during summers. it's interesting how indigenous mediterranean perannuals adjusted to dry summers. mostly they're evergreen plants. there's even evergreen type of oak here.
last year there wasn't any rain here from end of may to beggining of september, even pines, figs and old vines struggled from drought. my plants were loosing leaves so rapidly I couldn't deal with picking it so I used it as mulch. still had very nice harvest but believe it would be double at least with few summer rains. early strains are not so good in such dry seasons as they stop growing and start flowering in the middle of dry season, fortunatly we have long growing season here. I have few ideas how to improve my holes for this year and water crystals surely go into the mix. I'm just not sure how much to use.