Are $20 lamps really needed? / Another Blue/Red Question Too

11 years ago

We're growing vegetables, annuals and perennials from seed in an outdoor greenhouse (Zone 5b). Currently, we have 4 - 48" long, 4 bulb each, T5 HO fixtures, with built-in reflectors.

Regarding bulbs: we purchased a case (25) of the below bulbs, for around $80. This included shipping. This seemed to make sense, with respect to the higher individual cost at the big box stores.

FL54/T5/865/HO - 54 Watt - T5 High Output - 6500K - 800 Series Phosphors - Plusrite 4129

I'm still confused over whether we really need to have warmer lighting as well, or whether the existing bulbs will be sufficient. We hope to grow vegetables in the greenhouse over the summer and move the flowers out when we can plant outside safely. Lumens numbers are great, with lamps a few inches above the tops of the plants, as high as 55K+ where the lighting from the fixtures combines. (I have no idea how this will work with a taller plant).

In danbringhurst's recent post, aruzinsky suggested (among many) the Giesemann T5 Replacement Lamps, which are $20+. Depending on how much warm lighting I need (half and half?), what would you recommend for lamps? How do the benefits of the $20 lamp referenced above outweigh the benefits of a $3 lamp?

Thank you in advance.

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Comments (3)

aruzinsky
11 years ago
" How do the benefits of the $20 lamp referenced above outweigh the benefits of a $3 lamp?"

Nobody but you suggested "needed."

The benefit is educational. There are too many unknown variables to make an accurate prediction, therefore, as a good Samaritan, it is incumbent upon you to experiment, come back here, and tell us the results. You can put all special bulbs in just one of your fixtures and put $3 bulbs into the other three fixtures, as controls. I think that you can get a lower price for the special bulbs, if you shop around. And, incidentally, this would be an engineering experiment, not a "science experiment."
oldbat2be
Original Author
11 years ago
azurinsky - Thanks for your input. I think I'll be fine with the (cheaper) bulbs I have, as all seems to be growing well. I'm curious as to why this would be an engineering vs. science experiment? Wouldn't light be a typical control factor in a science experiment?

Per your comment: Nobody but you suggested "needed."

Was this in reference to my question as to whether we really need to have warmer lighting as welI? Are you saying we don't need red lighting for the flowering plants?

I am hoping to have all the annual and perennial flowers outside by the time they flower and looking for input as to what kind of lighting is required for this. The vegetables, we hope to continue to grow in the greenhouse. I could experiment by mixing in some red bulbs but that would predicate me keeping the same plants under the same bulbs. I have a really wide variety and move them all around as I water (and to adjust for sun).

This is so much fun!!
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aruzinsky
11 years ago
" I'm curious as to why this would be an engineering vs. science experiment?" - Because the experiment has a practical goal, to acquire original knowledge that can immediately be used to minimize the cost of electricity for growing plants. Science experiments have no practical goals.

"Are you saying we don't need red lighting for the flowering plants?" - I am not saying anything about plants needing red light to flower.