Question 1

What is the Kelvin number? I need grow lights that are good for microgreens.

Accepted Answer

Short answer: These lights will work well for your microgreens.

For microgreens and most plants, the Kelvin number is less important than the PAR output. (PAR = Photosynthectically Active Radiation) I bought some of these lights to test them and I have tested the entire Barrina line of LED lights for PAR output including the shop lights. All them will work for you. I did not test for Kelvin output. The specific frequency output on which the Kelvin rating is based, is provided as a graph by the manufacturer on the product page. But if I had to guess I'd say the output was 5,000 Kelvin or lower; so it's a relatively warm colored light which might be good for your purposes. Some researchers have gotten very high microgreen yields using lights with a higher red to blue ratio. My family grows microgreens and other crops commercially and we use Barrina LED lights almost exclusively. These lights will work well for greening your microgreens, but we actually don't even bother with lights specifically marketed as grow lights for our microgreens because we found that nearly any lights are adequate for that purpose and others are less expensive. We use the cheapest Barrina general utility strip lights and they work great. The specific lights we are presently using for our microgreens is the following light which has a kelvin rating of 6,500 which is a bright, cool white that is higher in the blue range: https://amzn.to/2QDJ2HW  We use 4 or 6 of these about 10" above four 10x20 flats of microgreens on 48"x18" wire shelves. I recently began removing the diffusers from these lights because doing so more than doubles the PAR output making them more useful for our vegetable and flower seedling starts, but be advised that doing so absolutely voids the warranty. I don't care about the warranty. I've been using these lights for more than a year with no problems whatsoever and they are cheaper than dirt to replace in any case.  If you remove the diffusers, just don't get any water or dirt on the LEDs.

Question 2

What is the umol/j

Accepted Answer

If you look at the last image it has a chart showing the umol at different heights.  But I would be careful place them to close in a real world situation depending on the growth stage of that plant you could cause some leaf burn.  These are very powerful lights in small foot print. From my experience with these lights I went down 10" .  I've tried it to get to around 150  umol/m2/s  aka the sweet spot, but I noticed right away by examining the leaves  under a loop I had an issue.  I hope this has helped.   So I just stick with 12" just to be safe.

Question 3

For starting seedlings, is one strip enough to light a 4' x 2' area or should I use 2?

Accepted Answer

I have them, and I would use 2 to keep the plants from "leaning".

Question 4

Is this really full spectrum or just 6500K

Accepted Answer

Dear customer,
  These lights are not 6500k. They are full spectrum.The spectrum is different from shop light. Our listing shows the spectrum graph. Please check. Thank you so much.

ASIN	B07ZJKL5F7
Best Sellers Rank	#5,368 in Patio, Lawn & Garden ( See Top 100 in Patio, Lawn & Garden ) #12 in Plant Growing Light Fixtures
Brand	Barrina
Brand Name	Barrina
Brightness	2900 lm
Bulb Base	G13
Color	Pinkish White
Connectivity Protocol	Wired
Control Method	Touch
Controller Type	Push Button
Customer Reviews	4.6 out of 5 stars 13,418 Reviews
Finish Types	Brushed
Fixture Type	Removable
Included Components	Bulb, Connecting Cable, Instruction Manual, Mounting clips, On/off Switch Power Cord
Indoor Outdoor Usage	Indoor
Installation Type	Hanging Mount/Ceiling Mount
Item Dimensions L x W x H	47.1"L x 1.3"W x 1.38"H
Light Color	Pinkish White
Light Fixture Form	Ceiling
Light Fixture Installation Location	ceiling
Light Output Maximum	2900 lumens
Light fixture form	Ceiling
Lighting Method	LED
Manufacturer	Bailina Lighting Electric Appliance Co.,Ltd
Manufacturer Part Number	QL42
Manufacturer Warranty Description	2 years warranty.
Material	Aluminum , Polycarbonate
Material Type	Aluminum, Polycarbonate
Model Number	QL42
Mounting Type	Ceiling Mount
Number of Items	4
Number of Light Sources	4
Other Special Features of the Product	Energy Efficient, Linkable plant light, Full Spectrum, High PPFD, V-shaped Reflector Design, high-efficiency heat Dissipation, Easy Installation, Flexible Mounting Options, Hanging plant lights
Power Source	Corded Electric
Recommended Uses For Product	Plant Growth
Room Type	Home Office, Kitchen
Set Name	4-Pack
Shade Color	white
Shade Material	Top quality Aluminum & superior PC
Shape	T8
Size	4ft-4 Packs
Specific Uses For Product	Garden, Greenhouse, Home, Indoor, Plant Grow Ghelves
Style	Modern
Style Name	Modern
Switch Type	Push Button
Theme	Gardening/Indoor Plants
Unit Count	4 Count
Voltage	120 volts
Warranty Type	Extended or Limited
Water Resistance Level	Not Water Resistant
Wattage	42 watts

Barrina T8 LED Grow Light 4FT, Full Spectrum, Pinkish White, 4 Packs

Details

Details

Description

Specifications

Common Questions