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LED Grow light

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NewbieGrower

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Howdy, I have the VIPARSPECTRA Reflector-series 900W LED Grow light with a 120cm/120cm/200cm grow tent. I was wondering when it's most beneficial to use the VEG/BLOOM lights. After doing some reading there seems to be some conflicting opinions. According to what I've been reading plants are affected differently by different wave lengths of light, hence the separation between VEG(Mostly blue) and BLOOM(Mostly red).

However, I've also read that the "downside" of using VEG/BLOOM together in the Vegetative stage is that it causes the plants to "Reach" more, or gain more height and less width. But from my, rather limited understanding I admit, it seems that's more of a training issue? You could dictate the path the plants follow (providing you have enough light coverage) regardless, so it would only make sense to increase the intensity of light (Withing reason, at the correct distances) to gain more growth in the vegetative stage. Although the provider, VIPARSPECTRA, mentions in the handbook that I should use the VEG switch for the vegetative stage, and then the VEG&BLOOM switch for the flowering stage. I'm not arrogant enough to presume I know better, so I was wondering if anyone has any insight to give?

Thanks!
 
Blue light is the main supporter of vegetative growth. When the plant stretches, it is looking for blue sky light.
The red spectrum range is the main supporter of flowering plants, that are not interested in growing larger with more stems and leaves, but is concentrating on making flowers.

If you believe in the product, use it as the manufacturer recommends. This will give you a "base line" for the performance of the light and you can experiment to do better after that.
 
You can absolutely go either way: Both switches from start or Veg only until Flip. As I said before, I started with just Veg and flipped Flower on one week prior to 12/12.
A few thoughts on this:
1: Viparspectra lights use about half the electricity when on Veg only. This might be considered a good thing or a bad thing.
2: With Veg only there was very little heat and humidity impact from lights. With both, Heat is about +5F and Humidty is -5% tent relative to room. (I have 2x450 rather than 1x900, so you will be a little different, but gives an idea)
3: With Veg only, I found the plants happiest at 21" rather than 24" recommended by Viparspectra. I increased to 24" when I flipped on both and then allowed plants to grow into 15-18" now that they are in flower. The Flower distance they recommend seems correct, but the plants all really wanted lights closer than 24" in Veg with Veg only.
4: #3 above was really prompted by your comments about "reach". I wanted my plants to reach less so that internodal length was smaller. It is true that you can correct shape of plant with training, but it is helpful if they just grow nice and compact and are not reaching for light.
5: I suppose that if my goal was to bring plants to harvest as quickly as possible I would probably use both switches the whole time. But that wasn't my goal.
 
Hello again! And you're swinging me towards using both, I don't know why it just doesn't sit right with me to only use "half" the lights. I live in a very humid/cold area, so the increase in heat definitely isn't a bad thing. That's one of the biggest hurdles I'm facing currently. Truth be told I don't really have a goal, I'm just considering all my options.

Appreciate the comment!
 
Hey Newbie!
Yes, I would consider the heat and humidity. and both switches may really be your best option.
I have been thinking about humidity in regards to your set-up. I live in LA. Temps 50-70F and humidity in the teens. Running 7-gallon fabric pots with coco and daily watering produces a lot of humidity (five quarts of water go somewhere other than the drain every day in my set-up). I can control this really effectively since I have access to unlimited dry air. I suspect controlling humidity will be one of your bigger challenges.
 
I've been running a few informal tests using the light/extractor system in an empty tent.

Without the light (day): Stable temp: 59F, Humidity: 72%
With the light (day): Stable temp 72F, Humidity 60%
without the light (night): Stable temp: 53F, Humidity: 78%
with the light (night): Stable temp: 64F, Humidity 76%

The temperatures are swinging far too much, I think the biggest thing I've got from reading the forums/GWE is about consistency in every aspect (nutrients/light/temperature/Water Ph TDS ect). To that end...

I've bought a dehumidifier that I'm going to test out today/tonight, I'm also wondering if the ventilation system needs to be on constantly? It swings the temp. I think if I could cycle it it wouldn't be as impactful. Say every 15 minutes on for 1 minute. The fan is rated for clear my tents volume of air every minute or so (When divided down), so I can't see the harm in doing that. I was also considering buying a small (40w/80w) greenhouse heater to turn on during the "night" periods.

Thoughts?
 
Yes, agreed. Heater and dehumidifier will be very helpful in your situation. I would suggest running your tests with fabric pots full of wet coco (as much as will be in there during grow). This will give you a better idea of the humidity issues you will have. Although you still won't have the plants transpiring, you will get the pots evaporating for a better simulation.
Other thought: If you turn off the ventilation system when tent has wet coco and transpiring plants, the humidity will spike instantly. You may be able to handle that with dehumidifier, but I must leave my ventilation on all the time because of humidity.
 
Also, looks like you should run lights at night. "Without the light day" and "with the light night" are too cold and wet, but a pretty reasonable range to work with.
 
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