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Gary350
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Location: TN. 50 years of gardening experience.

LED Seed grow lights how many Lumens ?

I want to build a 2ft x 3ft onion seed grow table to sprout 200 onion seeds. What LED lights is everyone using that produces very close to sun light 5500K light? How many total Lumens do the lights need to be? There is probably some way to know how many Lumens LED lights need to be?

I have every thing to build this but the light.
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Happy Grower
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It really depends on so many factors. None flowering crops can get away with relatively low lumens so long as your light is close enough to the plants. Typically you would use 7000 lumen per square foot, but I reckon anything 2,500 upwards to 5,000 would be adequate for onion plants. Then specifically seedlings... you need to keep your lights on the low side of that power range until your plants are on an or two high

I should have also commented with LED you really want blue light for vegetation and red light for fruiting, so I would recommend something in the 4000k range for onions. Unless you intend changing bulbs or having an LED with full spectrum that you can switch over during the cropping stage of growth to 2500k

But honestly, I wouldn't get too hung up about it as you will notice a huge difference on non-flowering or fruiting crops

Nyan
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Location: North Alabama Zone 7B

We bought a 4' X 8" full spectrum light (80 watts, four bulbs) at the local Rural King for $29.99 to do our seed starting this year.
It has worked wonderfully with all the veggies, using it on everything - celery (wife is a newb... LOL) peppers, tomatoes, cabbage, cauliflower, etc.
I think it would have enough light that you wouldn't have to worry about them growing well, though two of them would give you a really full 2 ft wide light spread.

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Gary350
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Location: TN. 50 years of gardening experience.

Nyan wrote:
Thu Feb 25, 2021 11:07 pm
We bought a 4' X 8" full spectrum light (80 watts, four bulbs) at the local Rural King for $29.99 to do our seed starting this year.
It has worked wonderfully with all the veggies, using it on everything - celery (wife is a newb... LOL) peppers, tomatoes, cabbage, cauliflower, etc.
I think it would have enough light that you wouldn't have to worry about them growing well, though two of them would give you a really full 2 ft wide light spread.
How many Lumens are your lights?

Nyan
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Posts: 103
Joined: Thu Mar 24, 2016 10:44 pm
Location: North Alabama Zone 7B

Not sure, but using the average output of 73 lumens per watt for a LED would give 5,840 for the whole unit. at 4 ft by 8 inches (2.68 sq ft.) would be about 2,200 lumens per square foot right up under the bulbs. We have the bulbs about 3-4 inches above the plants, which allows it to light one of the el cheapo cell pack planter containers all the way across on the narrow side.
We've had good success with it this year, with the plants looking very good and needing to be re-potted in the next few days.



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