BAsic lights questions

Tryong to wrap my head around lights. I’m well into my first grow and I keep seeing people mention switching lights from one to the other when it’s time to Grow in vegetative state versus flowering with another light.

Is this a wattage thing? Color spectrum? Heat? And most importantly should I have bbought a second set of two lights for flowering for my autoflower plants?

Thanks and sorry if this has been covered. Have a nice day, Bill

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Most of the time when people change lights from veg to flower it’s with bulb lights not with leds I don’t know much about bulbs so I can’t explain why n how I just know they did change because of light spectrum… newer leds are full spectrum and can go from seed to harvest, the only change is normally because they’ll use a lower power led for veg and higher power for flower or just have separate tents for each so they will have something flowering all the time


First know what kind of lights you have. Assuming you are familiar with light schedule for Veg vs Flower. Most people will run 18 hrs on for Veg/ 6 hrs off. Once you go to flower most will run 12/12. If you have a full spectrum light you won’t need to switch lights for flower just change schedule. If possible let us know what brand of light you are running.


It is in part because you do not need as many watts during veg as during flower. Most LED lights have a potentiometer (dimmer). You will read in the forum that “I set my light at 50% and set the height at 24”.
At 50% the light intensity is lower and its power consumption (watts drawn at the wall) is also reduced.
Alternatively, some will use smaller lights during the veg period. This is an example

The long slender light closest to wall is a Growcraft X1 Mini from Chilled Tech. It is a relatively low power light drawing only 64 watts at its max dimmer setting. When I bought this light I had the option of choosing two specific light spectrums. One optimized for vegetative cylce (which is what I bought) or with a full spectrum optimized for flowering. I wanted this light specifically to start seeds, veg seedlings and for clones. In the picture is three clones. You can see, given their size, vegging plants does not need a whole lot of watts. Combined the two lights are around 130 watts.
The other light is an old tech “blurple”. It manages spectrum with two rocker switches. Bloom and Veg
Since I only need it for Veg, I flip that switch and it turns the veg diodes on. This light does not have a dimmer. The two switches in a way function as a dimmer. If both switches are on it draws 125 watts. It draws roughly half that when only one switch is on. You would definitely what both Veg & Bloom switches on when the plants are late veg and flowering. I otherwise use it for supplemental lighting or in combination with another similar light.
This is are very common and popular Full Spectrum light. It is a HLG 260W V2 Rspec LED. At full power is draws 250 watts and is designed to veg a 4x4 spec or flower a space that is 8 to 9 square feet.

Depends on what lights you have now. Give brand and model

That is enough from me. Hopefully someone can describe light spectrum. Here is the spectrum graph for this light


What light do u have can send pics

thank you @Bulldognuts I am running two brand new VIPARSPECTRA XS2000 lights.

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I tried to edit but cannot for now. I was asking more in general but here is the specifics"

per the recommendations on the info sheet I am running them at 22" above canopy (it said 16-20") at 100% intensity giving out
on the photone app on iphone 12 on “full sun” mode (with diffuser) across the two larger plants readings of PAR METER PPFD 884-962 mumols/m^2s and DLI of 60 mol/m^2d at both plants tops.

My first grow and am trying to go everything by the book as much as possible.

Another question for lights gurus I can run the lights much closer to the plants without much heat to the tops ( love these lights) and run at 60-70% intensity and get the same PAR or DLI as 100% a little higher off the tops of the plants, and run the temps in the room at 70 F versus 80-82 F. Is there a difference in height other than keeping the tops of the plants from burning from the physical heat of the lamps? here are pictures of the lights and my little early vegetatives oh and the person who asked about the lights timings these are autoflowers and I plan on running them 18/6 the whole time.

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it’s not only the heat of the light but the INTENSITY that matters in how close you put it. Light burn, isn’t just from heat :wink: @dbrn32 is probably one of the most knowledgeable folks around here on DLI and getting that right. 60DLI is a little high i think 45–50 during veg is what i was told you want to achieve and 35-40 during flowering cycle :slight_smile: happy growing

This is because of different plant responses to different types of light. If you have a balanced or more natural light spectrum there isn’t really any need to change from veg to flower.

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@dbrn32 Hi there. Thoughts on this? 500w from wall