I spent over 23 years there.
The light comes and goes like anywhere else. It's just during the solstice thats it stays "light" almost 24 hours, and even this effect is mostly up North. If you are living somewhere like Anchorage or farther south there is daytime and nighttime in every season. Of course the summer season is shorter than most places.
In winter obviously everything is grown indooors... for that matter, almost everything is grown indoors year round, but in the summer there are those who grow it out in the Matanuska Valley and places like that and apparently some of it is super killer (personally I never saw any that I KNEW was grown out there that was really killer, just good homegrown.) Everyone back then used to call their homegrown "Matanuska Thunderfuck", but it was nothing like the legendary stuff.
I have no doubt the they can grow some killer weed out in the valley... they grow record-sized vegetables out there due to the long daylight and fertile soil.
The indoor weed is excellent like in most places I suppose.
When I was younger we used to get killer weed and hash from all over the world up there... kickass weed from Hawaii, Thaisticks, Acapulco gold, elephant bud, black hash from Iran & Afghanistan etc. and lots of Lebanese blond and red hash too. That all changed about 20-25 years ago when they really started to crack down on smuggling and when they changed the laws for possesion.
They also have lots of money up there and therefore lots of money for law enforcement. Tons of cops with the latest equipment and not a lot to do.
But yes, I have seen weed grown outdoors there many times... I have posted before that they used to have a party called "Harvest" every year out in the Mat Valley when things were different. 3 days of bands and weed... they even had signs out on the main road thru town saying "Free Weed" with an arrow pointing towards the party. You had to park a couple miles away and hike in and then everyone got some free hash or weed. They sold mushrooms on the stage and at night I remember them bringing in a 6-8' plant on a motorcycle and leaving it for all to pick off of.
Those were the days in Alaska... they are now gone thanks to the "Moral Majority" and Republicans up there.