it certainly depends on where you live
if you live somewhere below the mason-dixon, you dont have to worry too much about plants going beyond 8 weeks of flowering
but if you live above, chances are you'll want to look into a strain that finishes in 7-8 weeks flowering, to avoid mold or the chance that the weather will just turn to shit during those last 2 crucial weeks
i grew 1 successful white widow outdoors last year, among a patch of about 10, it ended up being female, and ended up being stolen (of course) one thing i can say for it which i thought was cool, all the other plants had spider mite/aphid damage EXCEPT FOR the white widow.
i realize this is a horrible angle, but this is the last pic taken of the WW before theft i believe it was last year in early september
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as far as strain reccomendations i would say purple power, maybe Skunk 1, outsider, early bud, early pearl (although i've heard some bad things), Kodiak and others that finish around 8 weeks or so. do some research on seed boutique or something... hope i could help