There are 2 types of HID grow lights used for indoor marijuana growing, high pressure sodium (HPS) and metal halide (MH). These come in a range of sizes, the most common being 175 Watts, 250 Watts, 400 Watts, 600 Watts and 1000 Watts. Anything over these size bulbs become less efficient for growing and you should consider using multiple sets of smaller bulbs, we even suggest that at the 1,000 Watt level.
| Lamp Type | Watts | Lumens /bulb | Total efficiency |
| Metal Halide (MH) | 400 | 36,000 | 36k lumens |
| High Pressure Sodium (HPS) | 400 | 45,000 | 45k lumens |
The size of bulb you purchase will depend on how many plants you want to grow. This varies widely, depending on the strain of marijuana and on how much vegetative growth you want them to have. It is better to calculate your requirements by area and a rough guide would be:
- 250 watt bulb will supply enough light to cover a 2.5’ x 2.5’ (75cm X 75cm) area (6 plants or fewer)
- 400 watt bulb will supply enough light to cover a 4’ x 4’ (120cm X 120cm) area (12 plants or fewer)
- 600 watt bulb will supply enough light to cover a 5’ x 5’ (150cm x 150cm) area (18 plants or fewer)
- 1,000 watt bulb will supply enough light to cover a 6.5’ x 6.5’ (2m X 2m) area (30 plants or fewer)
High intensity discharge (HID) grow lights can provide light in the right spectrums used by marijuana plants to grow successfully without sunlight if used in conjunction with each other.
High pressure sodium (HPS) grow lights used to be one of the most efficient methods of turning electricity into usable light. These days LED grow lights offer a far better use of power. HPS grow lights work well, are cheaper to buy upfront but produce a lot of heat which has to be managed and their bulbs and ballasts have to be changed far more regularly than LEDs. HPS grow lights operate in the warmer colors, yellow, amber, orange and reds which are most useful for marijuana flowering (budding). HPS lights are deficient in the blue spectrum but their amber to reds light bands triggers hormones in the marijuana plant to start the flowering stage. HPS are great for supplemental lighting and often last far longer than a similar MH light.
Metal halide (MH) grow lights produce light in the blue / green spectrums and are more useful in the vegetation stage. They grow the plants leaves and stem, make it big and ready for flowering. These bulbs will last anywhere from 3,000 to 10,000 hours depending on how many times they are turned on and off and the brand or quality of the bulb.
*** Detailed marijuana grow light overview ***
Thats not just logic. Thats really sneisble.
Good to see a tnaelt at work. I cant match that.
DEAR ADMIN;
THANK YOU FOR ALL THE DETAILED VERY USEFUL INFORMATIONS!
I LOVE YOUR WEBSITE THE MOST OUT OF ALL THE GROW MARYJ SELF-HELP PAGES OUT THERE!
I HAVE ONE VERY IMPORTANT QUESTION, THOUGH…
AS FOR GROWING OUTDOORS IN THE TROPICS WHERE WE BASICALLY HAVE 12 HOURS SUN LIGHT ALL YEAR – HOW MUCH DIFFERENCE DOES IT MAKE INTO THE WHOLE PLANTING RITUALS? DOES IT APPLY TO GROWING IT INDOOR AS WELL?
DO I STILL NEED TO RESPECT THE “CULTIVATE IN AUTUMN” RULE OR CAN I START PLANTING AT ANY TIME OF THE YEAR?
THANK YOU FOR YOUR ATTENTION…
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hi, ijust bought my tent and want to try indoor. can you tell me what else i need? myabe for 18 plants. but i dont want to spent too much.
you dont have to have that much light is only 125 600 is to much it burns it i think
ec what strenth do i need to take it in flowering ?