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Flourescent Bulb Color Temperatures Question...

Posted by arjo_reich 6a (Nashville, TN) (My Page) on
Tue, Jun 24, 08 at 12:07

Surprisingly, I couldn't find this through a search of the forum archives but I have to admit the search feature on these archives is rather limited...

I'm looking to start a simple row of seedlings - maple trees, to be precise - and I'm trying to figure out which types of bulbs for my F18T8 ballast would be the best. Currently I have several "Plant & Aquarium" bulbs which don't list anything by way of CRI or color temperature and several "daylight white" bulbs that have a color temperature of 65,000K.

For germination and the first two months of growth should I use all of one, the other, both or something completely different altogether?

The plan is to have three of the single bulb ballasts running horizontally over the two seed trays about 2-4" inches away from the plants - well, soil until they germinate. I just can't figure out which would be best for the first couple months of the plant, obviously there'll be no fruiting for years, lol...

Follow-Up Postings:

RE: Flourescent Bulb Color Temperatures Question...

Maples (Acer species)

When mature, maple fruit (samaras) turn from green to yellow or brown and fall to the ground. Collect mature fruit from the lawn, driveway, or gutters. There is no need to remove the seed from the fruit.

The fruit of red (Acer rubrum) and silver maple (Acer saccharinum) mature in late spring or early summer. Neither requires a pregermination treatment and should be planted immediately. The fruit of most maple species mature in the fall. Sow seed directly outdoors in the fall or plant stratified seed in the spring. Seed of the sugar maple (Acer saccharum) should be stratified for 40 to 90 days at 33 to 41 F, while seed of the Norway maple (Acer platanoides) require 90 to 120 days at 41 F. Plant the seed (fruit) 1/4 to 1 inch deep.

Either lamps will be fine. Some species seeds germinate better in the dark, others in red light, but I can't find any problems like that on google search. CRI is not relevant for plant growth, I think you seedlings will grow well with either just P&A, or just daylight 6500K, or a combination of both. The general rule with fluorescent lamps is the more lumens the better, and P&A do not have any practical advantage over any other modern high light output lamps. Sativa.

RE: Flourescent Bulb Color Temperatures Question...

I managed to find out that the P&A lamps only put out 590 lumens where as the daylight white lamps are 1350 each - which seems rather significant for a 24" F17T8 bulb - but I didn't know if the extra "blue" was better for germination or not in general...

RE: Flourescent Bulb Color Temperatures Question...

johnsmith I cannot find any CMH on that site you gave.
arjo reich : the way lumens are measured will make the p&a lamp look much worse than the actual growing performance, because it puts out only blue and red light, to correspond to the peak absorption of chlorophyll, and no yellow or green which measure very high with lumens, the lamp seems to put out very few lumens, but it still puts out plenty of photons in the areas that chlorophyll has peaks of absorption in, it works well as a grow light, just too pricey compared to a regular lamp, which grows just as well.
Plants have the intermediate carotenoid pigments that grab the yellow and green light, and pass on high energy electrons to chlorophyll, and that is why regular lamps work so well. Sativa.

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