Hi
Im doing a small gorilla grow this year, and had the same question recently....
http://www.marijuanapassion.com/forum/showthread.php?t=55266
The biggest problem you are going to have is getting them to take without going into flower. I am going to assume the cuttings are from a mature donor and have been under atleast 14 hours of indoor light so if you put them out before May 20 which is when the days are 14 hours long on a national average than you might see early flower.
Also you will want to get your plants used to the suns rays, this is called hardening. If you take a plant from inside and place it into direct sun it can "burn". I have the best experience keeping the plants outside all day for a total of 3 days, but in a spot where they are shaded most of the time, and then they can go into the ground. However my inside temp and outside temp is only a temp drop of 10 degrees, so if you live in a colder area, you will have to do the inside outside shufffle for awhile to acclimitize the plants to the temp difference.
The easiest way is to start from seed, you can get feminized ch9 from female-seeds for 17 pounds, with shipping thats 32 dollars US. I just started 5 seeds last week and got 5 sprouts. With seed the plants are new and have no light time stamp on them, and they grow into the season, and as they mature they stay in veg as the day light hours get longer.
Not saying you cant get the clones to take, but you will have to reduce the light period they are getting to 14 hours keep it there for atleast 2 weeks (to be safe) and then harden them outdoors. Getting clones out can be difficult, but it can be done.
I have had a seasoned outdoor grower on another forum tell me that 13 hours of sunlight will allow "most" strains to take as clones provided they were at 14 hours indoors. However, he also said that with all of the hybrid breeding going on now a days, if you buy seed stock it may contain sativa genes that will flower at the slightest drop in light period.
If this is your first outdoor grow, you may want to do the seed thing, or be prepared to reduce your light period on your clones
slowly as to not trigger flower, followed by a brief period of temp and sun hardening.
whatever you do, dig the biggest hole you can, and backfill with good soil, in the past I have used walmart soil bags for 4 bucs, because they do have a small amount of moss and manure in it. They are 11 gallons (1.5 cubic feet) so I dig a hole that will accomadate the bag of soil that is roughly 15 inchs cubed (15"x15"x15"). That size of a hole will leave a couple of inchs below the ground level so that I can top it off with natural dirt, this will help hide the spot and keep pests at bay. Rodents love the smell of fresh dug soil and manure. That is why its best to prepare your spots as soon as possible so they can "settle" to their surroundings. If you dig, backfill, and plant in a close interval, your going to want to screen the plant with wire or a soda bottle so that the same rodents dont get it. Rodents like weed as much as humans. Problem is that chicken wire and soda bottles attract human eyeballs and unwanted attention.
The key to successful outdoor gorilla grows is to scout locations. I start searching mine as early as Febuary. If your growing on your own land forget about what I said, but the hole size and backfill is important, unless you have naturally occuring soils that will provide good grows. Where I have seen a 1 pound plant grow in landscapping rock that had hard compacted soil underneath it.
The reason I say hole size is because it makes a difference with your final product. The same seasoned grower is in Arcata California and he or she has showed me where the same strain was grow in a 25 gallon hole vs a tractor dug hole of 200 gallons, both started at the same time, same light, and same watering schedule. The hole that was refered to as long as the length of a shovel yielded 7 pounds and the the smaller hole yielded 1.5 pounds.
My take on the outdoors, everyone says that indoor hps dro weed brings the best prices, but for me outdoor organic brings the best taste and smoke and thats what Im in the game for. Like Franco says, "the sun brings out terpins that indoors cannot".
Remeber harden, harden, harden
hope that helps, dont worry about people who tell u to go read, that just means they cant answer your question or they dont have the time to share their experience, and thats what this is suppossed to be for, sharing.
Good luck
P.s. If you do decide on some seeds, start them indoors under 14 hours of light, once they sprout keep indoors for 7 days and then you can start the hardening outdoors! Much easier, just remember, dont put outside until the nighttime lows are atleast 50 degrees and provided the days are close to 13 hours before they reach maturity they will keep going all season long! Its all about timing