BASIC QUESTION: It’s daytime and I turn on the lights in my greenhouse. Do the artificial lights add to the daylight and increase the overall DLI, or does the brightest single light-source dominate? RATIONALE: I have a 50 watt light source. It emits 800 LUX. I add another light source, of 100 watt, that is rated 1600 LUX. There is now 2400 LUX showing on my meter. (Yes, I understand the significance of PAR.) Surely, the same additive principle must also apply to the daylight combined with the artificial light that’s falling on my weed. EXPLANATON: Having measured the PAR of my lights, and checked on my geo-location figures (for the average DLI), I need to provide a further four hours of artificial light, on top of that which I’m already getting from daylight. The simplest thing to do is to turn the lights on for four hours as soon as the daylight fades. But, being that the two light sources are additive, I should be able to simply add the artificial lights to the daylight – I can have the lights on during the day instead of on at night. So – back to the BASIC QUESTION – It’s daytime and I turn on the lights in my greenhouse. Do the artificial lights add to the daylight and increase the overall DLI, or does the brightest single light-source dominate? In other words - can I ADD the lighting to the daylight during the day?
If you use a 1000w Light you will see a different, specially on cloudy days. With your Basement light of 100w you waist your money and hurt the environment by wasting resources. That Light doesn't do anything in a green house compared to a MH or HPS or LED
The lights add to the total DLI, so yes you add to the total available photons(sun and led) however the shadow of the fixture may well detract, as I was once told in Holland so the Dutch will often remove the light fixtures to expose the plants to the max of the sun I suggested he leave the fixture in place as the sun will rotate around the lighting fixture except for the plants directly under its really no biggy so long as you rotate all them plants daily cheers
Thanks for this - good point about the lights casting shadows. The reason I want to check about the additive effect (or not) is that I have 6 autoflowers and one photo-periodic plant in the greenhouse. The autoflowers are beginning to bloom and need lots of light. The photoperiod plant will start to flower with less than 12 hours of light - and I now have just about 12-12 of daylight. If I run my lights in the daytime, they are added to the sunlight - so in an 11½-hour period the autos and the photo all get lots of light, but the photo continues its flowering cycle (with less than 12 hour's light) . . . so I don't need to find a complicated way of depriving it completely of light for more than 12 hours.
with me I grow autos and photos in 2 different grow places, it make life a lot easier, many growers simply cover up the photo and leave the autos to shine, or simply put the photo, in a dark closet, you don't have to be totally dark, but its really strain dependent, even once acclimatized on their 2nd generation they get used to your grow methods ..lol