Will a 35 watt led lamp be good for sproutlings, and what height?

mikaroni · Feb 16, 2021

I just planted my seedlings into the soil, and put them in a propagator. At the moment I only have a little 35 watt LED lamp with 43 par. Would this be enough for them, and should I just put the lamp like 6 inches from the propagator? I simply cannot find any good info on this.

90'sStoner · Feb 16, 2021

How many seedlings and for how long do you intend to keep em under 35 watts. I'd say it'll do for now, but not for long

mikaroni · Feb 16, 2021

3 of them, may be 5 here soon. I just put them under the lamp about 2 feet above it. Should it be closer than 2 feet above?

LEDTonic - Max · Feb 16, 2021

It depends on what lamp you have and how it is shaped. It's more or less impossible to give accurate advice without this information.
The best option for you, if you have a real grow light that is intended for plants, is to look for a PPFD map (light intensity map). It should be found on the website where you bought the lamp.

Here is an example of how a map looks and how distance affects light intensity.

mikaroni · Feb 16, 2021

oh that's what that all means, ty. I ordered a big ass panel LED light, but the one i'm using now is just a little circular lamp that clips on to things. But what exactly does the example mean when for example it would be 6"/15 cm? 6 inches high for every 15 cm of?? per every 15 cm of plant height?

LEDTonic - Max · Feb 16, 2021

mikaroni said:
oh that's what that all means, ty. I ordered a big ass panel LED light, but the one i'm using now is just a little circular lamp that clips on to things. But what exactly does the example mean when for example it would be 6"/15 cm? 6 inches high for every 15 cm of?? per every 15 cm of plant height?

If the lamp is hanging at 6" (15cm) height in a 2x2' (60x60cm) reflective space, it will produce 680 PPFD in the very middle and around 70 PPFD in the corners.

If we raise it up to 12" (30cm) height, it will now produce 270 PPFD in the middle and 125 PPFD in the outer edges.

The shape of the light footprint changes when the lamp is lowered and raised and our human eyes are very bad at perceiving what the light intensity is below the lamp, so these maps are crucial to understand how a lamp performs and at what distance it should be hung. Plants will also prefer different light levels depending on their development stage, which is why 18" (45cm) distance is appropriate for seedlings (150 PPFD) and 6" (15cm) distance is appropriate for adult flowering plants (600 PPFD).

mikaroni · Feb 16, 2021

Oh ok ok. Thanks man. You've helped me a lot! I'm beginning to understand it better now.

LEDTonic - Max · Feb 16, 2021

That's awesome ;-)

Here's a detailed video on this subject if you want to dive deeper. It's packed with a lot of good information.

Southernontariogrower · Feb 16, 2021

When you get big panels, dim it right down or raise up high as some of these light will fry plant at full power if not hardened off. It took my plants a month to get used to led from se 1000w hps. Be careful not to kill them with love. You might want to buy killawatt plug and dim by voltage, easier.

mikaroni · Feb 16, 2021

Nice. Hmm, that video brings up another question. What tool is he using to measure PPFD? Looking online, I see different things like Quantum PAR sensors, "LED light meters", etc.

Imcamping86 · Feb 16, 2021

mikaroni said:
Nice. Hmm, that video brings up another question. What tool is he using to measure PPFD? Looking online, I see different things like Quantum PAR sensors, "LED light meters", etc.

Download a lux meter on your phone . Seedlings need at least 5-7k .

LEDTonic - Max · Feb 17, 2021

mikaroni said:
Nice. Hmm, that video brings up another question. What tool is he using to measure PPFD? Looking online, I see different things like Quantum PAR sensors, "LED light meters", etc.

This is the sensor and meter used in the video:

MQ-500: Full-Spectrum Quantum Meter

The MQ-500 quantum PAR meter is considered the gold-standard for accurately measuring grow lights with a highly refined spectral response of 400 to 700 nm making it ideal for all light sources including LEDs. It has a hand-held meter, attached via cable, that displays and stores measurements.

www.apogeeinstruments.com

The Apogee Instruments MQ-500 Full Spectrum Quantum Meter, Accurate for All Light Sources Including LED, Lightweight, Waterproof Sensor, Long Warranty. Made in Logan Utah by Apogee.: Amazon.com: Industrial & Scientific

The Apogee Instruments MQ-500 Full Spectrum Quantum Meter, Accurate for All Light Sources Including LED, Lightweight, Waterproof Sensor, Long Warranty. Made in Logan Utah by Apogee.: Amazon.com: Industrial & Scientific

www.amazon.com

mikaroni · Feb 17, 2021

LEDTonic - Max said:
This is the sensor and meter used in the video:

MQ-500: Full-Spectrum Quantum Meter

The MQ-500 quantum PAR meter is considered the gold-standard for accurately measuring grow lights with a highly refined spectral response of 400 to 700 nm making it ideal for all light sources including LEDs. It has a hand-held meter, attached via cable, that displays and stores measurements.

www.apogeeinstruments.com

The Apogee Instruments MQ-500 Full Spectrum Quantum Meter, Accurate for All Light Sources Including LED, Lightweight, Waterproof Sensor, Long Warranty. Made in Logan Utah by Apogee.: Amazon.com: Industrial & Scientific

The Apogee Instruments MQ-500 Full Spectrum Quantum Meter, Accurate for All Light Sources Including LED, Lightweight, Waterproof Sensor, Long Warranty. Made in Logan Utah by Apogee.: Amazon.com: Industrial & Scientific

www.amazon.com

God damn that's pricey! Still might get one though eventually. It'd be nice to be able to measure properly

mikaroni · Feb 17, 2021

Imcamping86 said:
Download a lux meter on your phone . Seedlings need at least 5-7k .

OK, I'll give that a go, thanks! Hey, I am seeing when looking lux meters up online that they don't properly record LED lighting. Think it will still work ok when using LED's? Also, do I measure near the top of my plant?

Imcamping86 · Feb 17, 2021

mikaroni said:
OK, I'll give that a go, thanks! Hey, I am seeing when looking lux meters up online that they don't properly record LED lighting. Think it will still work ok when using LED's? Also, do I measure near the top of my plant?

Yea on the top of your plant . I’m not sure how accurate they are . Still messing about with mine . So far it seems to be Okay. If it’s off a little bit I don’t think it will matter

Will a 35 watt led lamp be good for sproutlings, and what height?

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MQ-500: Full-Spectrum Quantum Meter

The Apogee Instruments MQ-500 Full Spectrum Quantum Meter, Accurate for All Light Sources Including LED, Lightweight, Waterproof Sensor, Long Warranty. Made in Logan Utah by Apogee.: Amazon.com: Industrial & Scientific

mikaroni

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MQ-500: Full-Spectrum Quantum Meter

The Apogee Instruments MQ-500 Full Spectrum Quantum Meter, Accurate for All Light Sources Including LED, Lightweight, Waterproof Sensor, Long Warranty. Made in Logan Utah by Apogee.: Amazon.com: Industrial & Scientific

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