how much damage can light during the night do and is there a strain that can flower

i have a place that i have grown in before and i ended up with very fluffy weak buds. Could that have been caused by the fact that it was never really dark where the planbts were. is there any strains like an auto flower i could grow in that spot that would be okay with the light at night.

Light leaks don't create weak fluffy buds, they can cause stretching, re-vegging and even hermaphrodites. Potency and Density are a result of Genetics and Environment (Lights, Nutrients, Air Flow, RH Etc...) and harvesting at the right time. Also yes, most autos flower regardless of the photo period, they don't re-veg and don't react to light leaks.

Outdoors it can really delay your girls from flowering.

I used to grow Oaxacan strain in the early/mid 70's,it always started budding around the the first weekend of August. As I lived in the sticks, one year I figured I'd put some plants in about 50-60 yards back of the barn,which had a dusk to dawn lamp on it. I figured it was far enough away that it wouldn't be problem. Wrong.

My girls down in the creek bottom flowered in early August,as normal. The one's back of the barn didn't start flowering until a couple of days shy of the first of of September.

Same strain,different spot,but one patch exposed to a bright light at distance. To top it off the back of the barn patch was my first experiment w/ growing sinsemilla. I got a few ounces of small bud,that was promising but not even a third of what I should have yielded. Needless to say I was pissed.

Auto flower's won't show any negative side effects from being exposed to both light and dark period's, other than lowering the yield. Since auto flowering strain's flower based on maturity not on photo period you can run them on 24 hour's of light and they can take advantage of all that lighting. So my advice to you is if your going to run auto flower make sure you have a 24 hour light environment.