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Thread: How many hours does my grow light need to be on if providing 250-300 PAR?

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    How many hours does my grow light need to be on if providing 250-300 PAR?

    I've found a lot of advice on lighting but most of it focuses on 15-30 watt CFLs, or fluorescent tubes, used as grow lights. I have a 300 watt Bloomspect LED growlight. I don't have a meter myself, but have found independent verification that it will provide somewhere close to 300 PAR at the height I have it above my plants. My current timer schedule has it running between midnight and 9am as it's too bright to run when I'm in the room (it's my office and I use the room from 9-5 every day, plus some evenings to game). I'm wandering if this is good, or too much, or too little so that I can adjust accordingly.

    Any advice? Can anyone point me to links or care sheets that reference PAR value or higher power grow lights?

    I'm currently growing 2 VFTs, a D Capensis, and a Sarr Scarlette Bell.

    Thanks.

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    How long have you been growing them under the light, and how do they look? Photos? ‘Scarlett Belle’ is a low grower so it should work okay under lights.

    I usually go for more like 15 hours but I haven’t used the type of light you’re using. (My main concern is with the Flytraps and Sarracenias not being dormant now.)


    Sent from my iPhone using Tapatalk

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    Thanks for the response, Bob.

    They came in a little under a week ago. I got them under the grow light immediately starting at 6 hours and increasing by 45 minutes each day since then until I hit the midnight to 9 schedule.

    I have some photos from a few days ago available here. They don't look much different now, and my Sundew still doesn't have any dew (I'm not sure how long it should take). It does look like there's new growth.

    I first just wanted to make sure I wasn't doing anything too far outside the norm that may cause my plants harm as they get used to their new home. Secondly, I thought if someone else had already done the experimenting it would help me get a lot closer to optimal from the start before I had to start experimenting on my own. Most threads I see do recommend 14-18 hours per day, but that's also with CFLs and other lights with far lower power output than the one I'm using, so I'm not sure how to adjust the timing accordingly.

    I just purchased the plants and was told I wouldn't need to worry about dormancy until next fall.

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    Not sure how much this helps you, but I have LED lighting (perfect spectrums for CP's) but I use mine in the 24 hr mode. It comes on dimmer, brightens to full, then dims again over the day, and only stay completely off for about 4 hours per day. My plants have done very well the last couple of years with good growth, nice greens and reds, as well as plenty of pitchers.
    If your lighting is only on/off, then I would suspect that the 8 hours down time per day would be sufficient? I'm sure someone else knows more than I do, but that would be my thoughts.

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    Quote Originally Posted by TheGuru View Post
    Not sure how much this helps you, but I have LED lighting (perfect spectrums for CP's) but I use mine in the 24 hr mode. It comes on dimmer, brightens to full, then dims again over the day, and only stay completely off for about 4 hours per day. My plants have done very well the last couple of years with good growth, nice greens and reds, as well as plenty of pitchers.
    If your lighting is only on/off, then I would suspect that the 8 hours down time per day would be sufficient? I'm sure someone else knows more than I do, but that would be my thoughts.
    That's really helpful, thanks. Would you happen to know the model number of your light so that I can compare the output to my own?

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    Quote Originally Posted by Nicholas_Bostaph View Post
    That's really helpful, thanks. Would you happen to know the model number of your light so that I can compare the output to my own?
    After a lot of initial research I went with the Finnex 247 Planted+ SE

    I recommend you copy and paste that into Amazon or Google, because the "+" and the SE are important. It has true 660nm red LED's as well as the more common 460nm ranges, which plants need both. Also, After over 2 years of continuous running this thing hasn't lost a single light in the array. Lastly, it is sleek and thin and adjusts in length. Mine is over a 55 gallon aquarium but they do have the same model in different lengths.
    Good luck!

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    That light is plenty powerful for what you are growing I would do at least 10 hours on though. Flytraps and sarrs love lots of light the Capensis will too but it will stunt its growth if you give it too much bright led (from plenty-o exp. growing under led) as for dormancy your flytraps will be just fine. Dormancy is a survival adaptation due to lack of light and bugs in cooler months. With that being said, your flytrap naturally experiences dormancy so ultimately for the most robust plant and longevity purposes dormancy even a short term what I call light dormancy is ideal. Skipping it once However will not kill the plant.

    What concerns me the most is that top hiding the light, those led units move lots of air and it may overheat it it isn’t getting enough air flow.

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    Quote Originally Posted by CouchLock89 View Post
    That light is plenty powerful for what you are growing I would do at least 10 hours on though. Flytraps and sarrs love lots of light the Capensis will too but it will stunt its growth if you give it too much bright led (from plenty-o exp. growing under led) as for dormancy your flytraps will be just fine. Dormancy is a survival adaptation due to lack of light and bugs in cooler months. With that being said, your flytrap naturally experiences dormancy so ultimately for the most robust plant and longevity purposes dormancy even a short term what I call light dormancy is ideal. Skipping it once However will not kill the plant.

    What concerns me the most is that top hiding the light, those led units move lots of air and it may overheat it it isn’t getting enough air flow.
    A good thing about the lighting unit I mentioned above is that the "shell" around it is aluminum, which conducts heat up and away with amazing efficiency. I definitely didn't want to go with a plastic for just that reason. As a result, the terrarium stays nice and cool.
    Of course, having sensors and keeping an eye on things are a definite must. For my plants, I have some on a raised platform that prefer more light, and those that prefer indirect light are lower down and even some that are under the canopy of another plants. Thus far, it's worked well for me. I'm just out of space, hence the greenhouse going up.

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