The Best Kelvin Rating for Plant Growth?

[Snazzy]

is there an ideal exact kelvin rating that you should get to get optimium growth? leaving out any opinions on what the light looks like but accual data that supports a rating? i know like 5000K to 10,000K will groe plants but is one better then another?

[Canoe2Can]

No, there is no single ideal Kelvin rating. Color temp is based on the light emitted by a theoretical black radiating body heated to ___ degrees kelvin. The higher the color temp, the bluer the light; the lower the color temp, the redder the light.

How well a particular light grows plants is based on its PUR, photosynthethically usable radiation. In the most general terms, plants like light in the blue and red parts of the spectrum. And color temperature is not a precise indicator of how much blue or red a light produces.

Anything in the 5000-10,000K range should work fine for plants. It's mostly a matter of personal preference. There are some tubes that are designed especially for maximizing PUR. Every one of these that I've ever seen was in the 8000-9300 K range.

[Snazzy]

so...for the T8 bulbs they sell at walmart and Home depot that say are for plant/aquarium rated at 2700k and 410lumens arent really that great for planted aquariums?

is it better to get the "daylight" bulbs around 5600k then the above 2700k bulb?

[mrbelvedere]

A GE 6500K Daylight bulb available at any Wal-Mart or Home Depot will be a wonderful tube.

[spypet]

Snazzy, think of it this way;

2700k is late afternoon color light, a few hours before sundown.
6700k is Noon color light on a blue sky cloudless day at the equator.
(most aquarium plants are from equatorial regions of our planet)

so, if you were a plant submerged under a foot of water
what type of light do you think you might perfer...

[Snazzy]

ok thanks

[RedIrocZ-28]

Yah, the 6500k lights at Home Deopt cost like $6.59. I picked up 2 of them for my HC grow tank that I'll be starting up today hopefully.

[Snazzy]

well after having the "plant and aquarium" bulb they sell at HD(which give a red hue) i think is working pretty good

because my set-up is a 6500k light in back and a 2700k light in front (the bulb above) the plants in front are growing fast and the ones in the back are growing a little bit slower and bending to be in more of the 2700k bulb
the plant that im talking about is r. rotfilia(sp) i have like mabe 20 stems threwout my 10gal tank lol