kosher said:
K I've got a 85 watt CFL that gives out 4,200 lumens as seen here:
http://www.goodmart.com/products/628131.htm
And i was thinking about getting a CFL 32 watt that gives out 2,100 lumens seen here:
http://www.goodmart.com/products/264348.htm
So with the 2 lights making a total of 6,300 lumens and 2 plants, will this lighting work?
Hey Kosher, good to meetcha man.
First, lets remember that Lumens are a measurement of average light on a globe exactly 12 inches from the source of light. MJ can grow fairly well using as little as 3,000 lumens, but a lot of the Hybrids are capable of using as much as 5,000-6,000 Lumens.
See-able lumens that are listed on bulb information are NOT the value that is accurate for a plant. It's a guideline, but the below chart will show you the best output for various types of lights. You'll see that for Plant Lumens, the Hagen Fluorescent 20 watt T8 PowerGlo bulbs are the best bang for the buck in the amount of Plant lumens received per/watt of electricity.
If the surface of the plant is twice that distance, (like side and bottom growth), they receive half the amount of lumens. If you want to place additional lighting, you need to remember the 12 inch rule of Lumens. Put the additional lighting in areas that will increase the lumens to that part of the plant. Please remember that the 12 inch rule for lumens is a method of measurement, not the distance you place your light from the plant. That will vary with the type of light, light cooling, plant heat guards and ventilation.
You could use two 250 watt HPS in the area you've described and it would provide enough light to maximize your transpiration rate. Or, you could put a four foot T8 fixture above the plants and maximize your light and cost effectiveness.
The information shown in the chart attached comes from:
Lumen Information for Plants
NOTE: PGL = PLANT GROWTH LUMENS