Rahz
Well-Known Member
I've read a few university papers on the subject, though the plants used vary. In one study strawberry plants were grown under both blue or red light. Plants were cut up and separated into leaf, stem, and bud. The blue dominant light produced the heaviest leaf weight while the red dominant light produced the heaviest stem weight. This follows the general idea that blue light promoted close internodes.
For the veg period the light a person chooses may depend on what they're trying to accomplish. For instance, in a sog a balanced spectrum (3:1) in veg and flower might be a good idea. If you are only growing a few plants in a scrog and want the plants to veg with longer internodes going heavy on red for the first 3 weeks might be a good idea. That vertical growth under the screen can be translated in lateral growth. Once the screen is full a more balanced spectrum would be appropriate going into flower so internodes shorten and leaf matter bulks up a bit as the buds are getting started.
I've been using 3000K t5s for the whole grow and suspect either the light is just weak, or there's not a whole lot of blue as I get fantastic (desired) stretch in veg and then fantastic (undesired) stretch going into bud production. Looking at some spectral charts the CFLs don't have the same full bodied spectrum white LEDs have and get their rating by mixing relatively narrow bands of red, green, blue. In some charts for 3000K bulbs green is used more than blue to achieve the Kelvin rating. In the Cree3050 100watt LED thread you can see how the 2700K spectrum produces nice unstretched plants while I'm getting 5 foot monster plants growing under 3000Ks.
So even the K rating isn't going to be an absolute indicator of anything. I'll probably be using 3000K cfls for veg to get my stretch and then switch to 2700K LEDs for flower! Ain't that something?
For the veg period the light a person chooses may depend on what they're trying to accomplish. For instance, in a sog a balanced spectrum (3:1) in veg and flower might be a good idea. If you are only growing a few plants in a scrog and want the plants to veg with longer internodes going heavy on red for the first 3 weeks might be a good idea. That vertical growth under the screen can be translated in lateral growth. Once the screen is full a more balanced spectrum would be appropriate going into flower so internodes shorten and leaf matter bulks up a bit as the buds are getting started.
I've been using 3000K t5s for the whole grow and suspect either the light is just weak, or there's not a whole lot of blue as I get fantastic (desired) stretch in veg and then fantastic (undesired) stretch going into bud production. Looking at some spectral charts the CFLs don't have the same full bodied spectrum white LEDs have and get their rating by mixing relatively narrow bands of red, green, blue. In some charts for 3000K bulbs green is used more than blue to achieve the Kelvin rating. In the Cree3050 100watt LED thread you can see how the 2700K spectrum produces nice unstretched plants while I'm getting 5 foot monster plants growing under 3000Ks.
So even the K rating isn't going to be an absolute indicator of anything. I'll probably be using 3000K cfls for veg to get my stretch and then switch to 2700K LEDs for flower! Ain't that something?
