Lights

[Melminster]

Is it helpful or harmful to add lights during the flowering stage

[dilvish]

You'll have to provide more info. That's a pretty ambiguous question and the answers may not be what you are looking for.

[gbauto]

It is common to ramp up the light intensity at the end of your veg cycle and into flowering.
Think of it this way-you're reducing the 'watering' time the lights are on from 18 hrs to 11-12 hrs.
To provide the same amount of light in less time requires a higher intensity.
The most accurate way to set light intensity would be to use a PAR meter.
I try not to exceed 1000 umoles ppfd at the top of the canopy.
If you're running enriched co2, you can go up closer to 1500 umoles.

[Melminster]

I only have a few weeks left before harvest. I just bought new lights for the next grow, and was wondering if i could add the new to the existing setup with any benefits. Or if its harmful.

[dilvish]

Cannabis loves light. Period. Unless you are growing with the lights too close, there should be no issues. Light burn can be a problem but it's typical only when the light source is too close to the top of the canopy.
The other thing to consider is cost. Are the lights costing more in electricity? IMHO 600W LED with full spectrum is plenty for 4 plants. Add 100W for each additional plant. More lights may not be necessary in terms of cost of electricity that's why many growers tend to use 18/6 for Autos even though they can be set 24/0. Those that leave their lights on all the time during the entire grow are just wasting electricity and money.