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Questions [Completed] Light Intensity Seedlings

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Topic starter

What distance/ intensity should LED light be for brand new seedlings that just broke through the soil?


7 Answers

CFL or florescence's are better . LED's are too strong, but if you have to use them turn them down as low as possible and put them at a height of 36"/90. If they are still too strong I have used a white paper plate placed above the seedling as a filter. They still get the light but it's buffered. But keep them high above and low on the intensity. keep the RH as high as 70% or put plastic domes on them and put a paper plate on top of that. Done. Let them sit till you have the first set of leaves. One leaf. Then you can start to introduce more direct light. What type of LED do you have?

Lemi Lemi Topic starter January 6, 2022 8:46 pm

I'm using a 450 watt equivalent LED light. I have it 36" above canopy right now. The light is dialed in at 30% intensity. I plan on slowly increasing the light as the plants mature.

WoodI2 WoodI2 January 6, 2022 10:54 pm

By week three they can start to handle full power. The first few days 3-5 they are at they're weakest. Treat them with care and just let them get a few days under their little belts before anything fancy. I would turn it all the way down and just let them sit. They are actually very busy and need to be left along to get established. They're too fragile atm, handle with care.Β  πŸ‘ Β 


So ideally you want to keep your par level in range, that can be done via dialing back the power on the driver and or raising the light fixture to get the par level desired at the canopy. I keep the bloom plus lights at maximum power and raise them till I'm in par range, the new se7000 i have would fry them like kale chips if i tried that so i dial back the power at the driver instead. really depends on what lights and what space you are working with.

I feel like a, like a slice of butter... melting on top of a big-ol' pile of flapjacks... yeah.


I think Monkeydo shared this chart previously, and I saved it for reference. My seedlings have done great and have thrived as teens using these par levels with my cheap LED.Β  Good luck, mate!

PAR grow chart

To see a World in a Grain of Sand, And a Heaven in a Wild Flower,
Hold Infinity in the palm of your hand, And Eternity in an hour.
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Lemi Lemi Topic starter January 6, 2022 8:51 pm



Oh --Β  to be more clear, you would use your manufacturer's PAR map for your model of light to match these PAR recommendations at the right distance from the canopy.

To see a World in a Grain of Sand, And a Heaven in a Wild Flower,
Hold Infinity in the palm of your hand, And Eternity in an hour.
― William Blake


What wattage Is the light what diodes does it use how much height space do you have in your grow space I've got a 240 led that uses the Samsung diodes I've always used it on full power just raise the light as high as possible which for me with pot size etc is about 1m I've never fried them just put the light high and let the plants grow in to it they can take more than people think is it necessary probably not am I wasting electricity probably but does it work yep

Lemi Lemi Topic starter January 6, 2022 8:50 pm

202 watt(450w equivalent) Bridgelux LED's. I have it app. 36" above canopy. Since the seeds just popped, I have light intensity at 30%.


LEDs can be very different. Check the manufactures recommendation. Most have some information available on these things.

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I've been using a large spiral florescent on clones and seedlings. I suck at seeds though. I'm a cold-blooded killer. Lol. SMH.


I get near 100% on clones.Β 


I've been thinking about getting an LED for my seedlings but reading here, you guys probably saved me a couple of dollars. Lol

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