Using Metal Halide
Indoor Grow Lights
Some of the vegetative stage can be handled by fluorescent indoor grow lights. If your vegetative area will barely fit under 3 fluorescent light fixtures, and you rarely have plants larger than 24 inches tall, I would advise you to go this route.
When your vegetative area starts getting a little larger, or when you are growing plants larger than 24 inches tall vegetatively, it is time to break out the metal halides for your indoor grow lights.
Flowering plants stretch in the abscence of blue light. It is the blue light that keeps vegetatively growing plants short an stocky.
Metal halide indoor grow lights put out intense light high in the blue spectrum. It is just perfect for lush and vigorous vegetative growth, so long as there is also good air circulation and good temperature control. If you need to brush up on these things, check out...
and always be sure to use an oscillating fan on your plants, except for on your fresh clones.
How Close ?
Below is a general guideline on how close to keep the tops of your plants from the bottom of your metal halide indoor grow lights. A good indoor/outdoor garden thermometer will help you dertermine if you can go closer or need to stay farther in your own setup.
- 250 watt light............10 inches
- 400 watt light.......12-14 inches
- 600 watt light.......16-18 inches
- 1000 watt light..........24 inches
Not so much for Flowering
Metal halide indoor grow lights are very high in the blue light spectrum. Blue light is more beneficial to the healthy development of stems and leaves than to the healthy development of fruits, vegetables, and flowers.
The high pressure sodium light, on the other hand, is high in red and orange light and favors the healthy development of fruits, vegetables, and flowers. This is why most people will swith to HPS light for the flowering stage.
Changing from a vegetative photo-period to a flowering photo-period at the same time you change from a blue light spectum to a red/orange light spectrum makes the plants very eager to begin flowering.
Not so much for Clones either
Metal halide light is much too intense for seedlings and clones unless they are kept 3 or 4 feet away. This is a job much better suited for fluorescent grow lights. It will also cost less in electric this way.
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