I've gathered a lot of info since I last read this thread.

First off I too am using some 5000k CFLs to get some extra blue. However mine are in a home made hood intended just to start plants.

OK,

So, (hope I have this all straight). Early Red light is good because Spring time also produces red while the sun rises to it's summer high where it produces a lot of Blue. Thus Red light is beneficial to both Flower and sprouting. However Blue light is best for Vegitative growth(mid summer at mid day).

Here is why:

In the spring the lower intensity of red light is less harmful to the seed then intense blue. (beyond that no diff!)

The summer sun produces a LOT of blue light during mid day(away from the horizon) However it does produce Red during sun rise and set. The Plants Chloraphyl A (:wtf:<sp) uses Blue light to produce the proper sugars and hormones for the plant to produce more leaves. The morning and evening reds also help but not SO important at this stage of growth. It evolved this way in responce to the normal summer sun frequencies! :thumbsup: This causes the plant to grow bushy and dence.

When fall starts rolling around, the suns path in the sky moves closer to the horizon. The refraction of the suns light off the atmosphere turns it more red (although still producing a lot of blue at mid day!). Red light is used by Chloraphyl B. Which produces slightly different sugars and hormones then Chloaphyl A. The plant has evolved to use this increase of red light, and increase in the different hormones to assist in producing the flowers. Thus although the plant is not absolutely dependant on this red light to flower. The plant HAS evolved to use more of these chemicals produced by chloraphyl B for making the flowers.

So, If you use HPS(high red) for everything the plants may be taller and have fewer branches(lacks chloraphyl A's sugars and hormones causing mild streching). The buds may still grow pretty well though! after all it had all the right stuff to flower.

If you use MH(high blue) for all stages. The plants will be shorter and bushier(very healthy bush), but the flowers will be small due to the shortage of the correct sugars and hormones the red light would've produced.

If you use MH to veg, then switch to HPS for flower. You'll see bushy healthy plants. The flowers will be bigger and have more flowers due to so many branches forming during veg (getting into shading issues now). Only issue is the mild shortage of blue during flower. This may lead to some of the leaves dying off, and some streching DURING flowering.

If you use both the entire time time. You get shorter bushier plants high in all the sugars and hormones both A and B produce. The plants leaves will stay as healthy as possible during flowering(yellowing is still possible). The flowers themselves will be larger simply because the plant has everything it needs to keep leaves healthy AND produce flowers. streaching during flowering is also reduced.

So there's your answer. Not using blue during flower can cause some streching.

Hope you get more out of that then just what you asked. :thumbsup:

Good luck :thumbsup: