height is causing problems

I have a half and half room of silver haze ( sativa ) and himalyan gold ( indica ), flowering in the same room( 600 watt hps). My original idea was to have a good harvest at 8 wks with the himalyan gold then another a few wks later from the silver haze. Those damn sativa plants are over six feet tall, so i adjusted the light to 20 inches over their heads. Now my Himalayans are reaching like craaaazy, almost funny. Can I bring the haze plants outside for 12 hours and bring them in at night without them reverting. It would only be for a few weeks. The daylight outside is intense and is def putting out vegatative light, but is the spectrum Sooo important or is it the amount of darkness?

This is similar to a previous post I left, but i was wondering about temporarily taking them outside. Is this advisable? Bugs aside, would the daylight hurt my haze plants while i lower the hps for the last two weeks of himalayan growth?

As u can tell im still a bit hazy ( no punn intended ) about light spectrums. can anyone help me without making me feel like a moron.

The amount of darkness if more important than the spectrum. Switching back to veg will only occur if the plants have more than 14 hours of light At 6 feet tall I think it's way too late to LST. 2700k spectrum is what you want for flowering, but not having that won't make that much of a difference. What lights are you using?

600 watt hps. i ended up bending the himmys over to expose the spider buds and dropped the light an entire 3 feet. i also noticed that some of the shorter himmys have either nutrient burn on the top 3 tiers, or they are coming into maturity. they are still,as i said, a few weeks out from harvest. Is this normal?

Some yellowing is natural if you've flushed and aren't feeding any more nutrients as the plant is cannablizing itself to get the nutes it needs to survive. If you haven't flushed then I would assume it's nute burn. How many weeks from harvest? Kind of hard to tell what it is and isn't without pics. Where is the yellowing starting from?

There is no yellowing. The very tip of the top fan leaves are burnt, bout the size of the end of a pen. The hairs on the top few tiers are brownish red. They look like they are just mature, but small still. the plants have at least 2 weeks left till trichs turn cloudy id say, so ill chop in 3.
I fixed the height situation today tho. I grow in a building in a very rural lacation so im going to grow 10 haze plants on the porch during the day and bring them inside at night. I also boarded all windows in my building and turned it into a dark room. Ill post results if anyones interested. The himmy plants are bent over almost double, exposing the buds that were once shaded by those tall ass haze leaves.