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Thread: Light for Nepenthes

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    Light for Nepenthes

    Normally I grow my Nepenthes outdoors, but winters here are a bit too cold for the lowland species (Zone 9a). Last year, I tried putting them on a shelf by a windowsill (no supplemental lighting) and kept them in trays, but some of them did not make it through the winter. I've decided to get some grow lights to overwinter my lowland Neps this year, especially since I have more now and I'm sure that some of the ultralowlanders (i.e. bical) will not survive on a windowsill. N. gracilis, mirabilis, and maybe some of the small seed-grown species can do okay next to the window for sure, as they did fine last year.

    My planned setup is to have 2 trays of lowland Neps on a plant rack with some eggcrate diffuser lining the bottom of each tray. Each tray would be illuminated by 4 bulbs. The plant rack will be in my living room, so it will be ambient humidity (which is not super high). I'm not sure how much the water in the tray will boost humidity, but I can also put a large plastic over the entire set up (and purchase a small fan as well to increase airflow).

    Right now the main options I'm looking at are T5s and T8s (2 ft, 4 bulb). T5s would run about $80 for a 4-bulb fixture with bulbs included, while T8s vary from $14 for a cheap 2 ft 2 bulb fixture to $60ish for a 2 ft 4 bulb fixture. I know that T5s are supposed to give off less heat, but since I'm growing lowland Neps, wouldn't more heat be better? I don't plan on adding any extra heat to the plant rack beyond the temperature of my apartment (~65-75 in the winter) and any additional heat from the bulbs. I'm thinking of running the lights 14 hours on/10 hours off; this is based off of what I read about the 'standard' light schedule being 16 on/8 off but that they need less light in winter.

    Based on this, would you suggest T5s or T8s? T8s are definitely cheaper and should give off more heat from what I've read (which is good), but T5s should provide stronger light. With fall just around the corner, I'm planning on getting the lights soon before temps drop below 60F outside. The lights would only be used when it's too cold outside, so probably from late October/early November until mid March or so, after which all plants would go back outside. Any feedback would be appreciated.

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    nimbulan's Avatar
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    As I understand it, bicals can be adjusted to windowsill growing though it's certainly not the easiest plant to do so with. I have no experience myself since I have yet to obtain one, unfortunately.

    Are you sure the plants that didn't make it were due to low light levels? I would think that low temperatures would be a more likely cause. As for the light types: I believe that T5's and T8's run at roughly the same efficiency (T5's are probably a little higher,) but T5's can handle twice the power so they will put off more light and heat in general, but more or less the same amount of heat per lumen. It all depends on how much light you need.

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    Quote Originally Posted by nimbulan View Post
    As I understand it, bicals can be adjusted to windowsill growing though it's certainly not the easiest plant to do so with. I have no experience myself since I have yet to obtain one, unfortunately.

    Are you sure the plants that didn't make it were due to low light levels? I would think that low temperatures would be a more likely cause. As for the light types: I believe that T5's and T8's run at roughly the same efficiency (T5's are probably a little higher,) but T5's can handle twice the power so they will put off more light and heat in general, but more or less the same amount of heat per lumen. It all depends on how much light you need.
    It may have been low light or low temperatures or a combination of both. The temperature next to the window was around 60F at the coldest, despite the AC being set higher. Both of my amps perished in those conditions, as did a raff. Bicals might be able to adjust to a windowsill, but if the relatively 'easier' species couldn't make it, I wouldn't expect bical to.

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    Quote Originally Posted by Bluemoon99 View Post
    I know that T5s are supposed to give off less heat, but since I'm growing lowland Neps, wouldn't more heat be better?
    What is this based on? Electric power get converted to light or heat. So higher efficiency light gives more light and less heat than lower efficiency light. If you are talking about T5 normal output, then it has higher efficiency, so you are correct. But if you are talking about T5HO (high output), then the efficiency is pretty similar to T8. In lower temp, T8 has slightly higher efficiency than T5HO in general, and T5HO is slightly higher in warmer temp. So if you compare 1 bulb of T5HO vs 2 bulbs of T8 (to make the amount of light similar to each other), the heat production is similar. Now, there are some ballast related efficiency. Some cheap T8 fixtures may be using cheap, less efficient ballasts.

    This is the story when you have some enclosure to capture the heat. In a wide open room, this will not raise a lot of temperature (unless you have lots of them). But if you limit the heat radiated toward the plants from the light bulbs, we feel T5HO might give a bit more "dense" heat. But if you adjust the amount of light (density), it should be similar since the emission spectra is similar between typical T8 an T5HO.
    Last edited by naoki; 09-21-2016 at 11:33 AM.

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    duplicate. I don't know how to delete this.
    Last edited by naoki; 09-21-2016 at 11:34 AM.

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    Benurmanii's Avatar
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    T5HOs run hot, they give off the more heat than any other fluorescent tube I own. My T8s are practically cool to the touch compared to my T5HO fixtures.

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    nimbulan's Avatar
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    That's only because the tubes handle twice the power in a smaller form factor. The actual amount of heat produced per lumen is not really any different.

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    Quote Originally Posted by nimbulan View Post
    That's only because the tubes handle twice the power in a smaller form factor. The actual amount of heat produced per lumen is not really any different.
    But in terms to trying to make a space warmer, would T5HOs be better?

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    It shouldn't matter unless you can't physically fit enough T8's into a space to provide the required light level. For the same amount of light, you will get the same amount of heat no matter which type of bulb you use. People often equate T5 bulbs feeling hot to the touch with them producing more heat, but it's simply a side-effect of the bulbs being more powerful. A general rule is 2x T8 = 1x T5HO, both for light output and heat output.

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    Quote Originally Posted by naoki View Post
    What is this based on? Electric power get converted to light or heat. So higher efficiency light gives more light and less heat than lower efficiency light. If you are talking about T5 normal output, then it has higher efficiency, so you are correct. But if you are talking about T5HO (high output), then the efficiency is pretty similar to T8. In lower temp, T8 has slightly higher efficiency than T5HO in general, and T5HO is slightly higher in warmer temp. So if you compare 1 bulb of T5HO vs 2 bulbs of T8 (to make the amount of light similar to each other), the heat production is similar. Now, there are some ballast related efficiency. Some cheap T8 fixtures may be using cheap, less efficient ballasts.

    This is the story when you have some enclosure to capture the heat. In a wide open room, this will not raise a lot of temperature (unless you have lots of them). But if you limit the heat radiated toward the plants from the light bulbs, we feel T5HO might give a bit more "dense" heat. But if you adjust the amount of light (density), it should be similar since the emission spectra is similar between typical T8 an T5HO.
    I read this somewhere online, so it may or may not be true. The lights I'm looking at are T5HO - I forgot that they were high-output.
    When you say 'limit the heat radiated towards the plants', are you referring to using a reflector/reflective material?

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