wattage vs wavelength spectrum

[RedScare]

Chances are any fluorescent bulb that is mostly white will grow plants about as well as any other. Don't fall for the marketing ploys, those plant specific bulbs are likely no better than the generic bulbs at walmart. On the other hand, if you like a color, don't be turned away because people say the color temp are not ideal for plants. There is no ideal color temp for plants.

This is not true but I am only speaking from my experience. I took off my grow-lux bulb for a 6500k bulb and saw my amazon sword plants decline in less than a week. I replaced my grow-lux bulb and saw a recovery of about 2-3 new leaves per plant in less than a week.

 

[slink]

The green wavelength is the least beneficial to photosynthesis, which is why the plant grow bulbs don't use it.

Don't fall for the marketing ploys, those plant specific bulbs are likely no better than the generic bulbs at walmart. On the other hand, if you like a color, don't be turned away because people say the color temp are not ideal for plants. There is no ideal color temp for plants.

Now I'm confused. I thought the plant bulbs make sure that you've got plenty of color other than that which is within the green spectrum since, if you do, your plants won't grow. I thought you said this yourself in the first part of your statements. Perhaps what you mean is that chances are that the white bulbs include almost as much beneficial blue or red color as these special "for plants" bulbs.

 

[phanmc]

This is not true but I am only speaking from my experience. I took off my grow-lux bulb for a 6500k bulb and saw my amazon sword plants decline in less than a week. I replaced my grow-lux bulb and saw a recovery of about 2-3 new leaves per plant in less than a week.

There are exceptions to every rule. A specific bulb may simply be very poor at growing plants not because of the color temp, but because of the color spectrum they use to create the color temp.

Look at this bulb comparison chart that uses a PAR meter to compare lighting:
http://www.aquabotanic.com/lightcompare.htm

At two ends of the fluorescent spectrum are the "Philips Advantage fluorescent, 5000K F32T8/ADV850" and the "Philips TL950 5000K fluorescent very high CRI (98) F32T8/TL950". The ADV850 is the best bulb you can get for plant growth, it's K rating is 5000K. The TL950 is one of the worst bulb you can use and is also 5000K.

If you look at the efficiencies (PAReff) over the vast majority of bulbs tested, there is a difference of about 20% from the best to the worse with most fluorescent bulbs falling within 10% of each other. Even the grow-lux bulb doesn't really stand out from the crowd.

 

[phanmc]

Now I'm confused. I thought the plant bulbs make sure that you've got plenty of color other than that which is within the green spectrum since, if you do, your plants won't grow. I thought you said this yourself in the first part of your statements. Perhaps what you mean is that chances are that the white bulbs include almost as much beneficial blue or red color as these special "for plants" bulbs.

The first part I was simply explaining why a bulb with a very low K rating can grow plant just as well as a higher K rated bulb. I should have linked this earlier to further disprove the importance of the K rating:

http://www.aquabotanic.com/lightcompare.htm

"Perhaps what you mean is that chances are that the white bulbs include almost as much beneficial blue or red color as these special "for plants" bulbs" is exactly it.