Jimster
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I decided to try a new 10000K 1000watt Metal Halide light for a grow. The bulb was recommended as a "finishing" bulb, but since it had so much blue in it, I decided to use it for veg growth as well. I also used a 6K MH for the veg cycle along with the 10K bulb. From my observations, while I thought the 10K bulb would be better for vegetative growth, the plants grown under it were shorter than the others that got either the 6K light or a combination of the 2. I also got hit with spider mites, so that also could have shorteded the plant's growth, but they are normally much taller and I have grown them for many years.
During flowering, I got lazy and left the 10K bulb in place and swapped out the 6K for a HPS. There was a large difference in plant and bud size between the HPS and the 10K. It has been about 8 weeks of flowering, and the plants under the 10K are showing signs of being about ready, while the others seem to be still actively flowering. The plants that seemed to finish early, a Sativa strain I'm familiar with, usually took 10-12 weeks to finish, so it looks like I'm about 2 weeks ahead of schedule. I'm unsure how the potency or taste is affected, but the yield is significantly lower than under the HPS or HPS/10K combination. The true test will come in a few weeks! :)
So, in summary, the jury is still out for using the 10K bulbs for anything other than "finishing". I'm not sure why a 10K bulb would improve anything during the last weeks of a plant's life, but I'm open to suggestions. Both 3500K and 6K bulbs are great for veg growth, and the 3500K bulbs can be used for both with good results, if needed. The best results to date have been using a combination of a HPS and a 3500K bulb for flowering. I haven't tried HPS only for flowering, but might try it next time.
What is your experience with different "K" bulbs?
During flowering, I got lazy and left the 10K bulb in place and swapped out the 6K for a HPS. There was a large difference in plant and bud size between the HPS and the 10K. It has been about 8 weeks of flowering, and the plants under the 10K are showing signs of being about ready, while the others seem to be still actively flowering. The plants that seemed to finish early, a Sativa strain I'm familiar with, usually took 10-12 weeks to finish, so it looks like I'm about 2 weeks ahead of schedule. I'm unsure how the potency or taste is affected, but the yield is significantly lower than under the HPS or HPS/10K combination. The true test will come in a few weeks! :)
So, in summary, the jury is still out for using the 10K bulbs for anything other than "finishing". I'm not sure why a 10K bulb would improve anything during the last weeks of a plant's life, but I'm open to suggestions. Both 3500K and 6K bulbs are great for veg growth, and the 3500K bulbs can be used for both with good results, if needed. The best results to date have been using a combination of a HPS and a 3500K bulb for flowering. I haven't tried HPS only for flowering, but might try it next time.
What is your experience with different "K" bulbs?