3000K vs 4000K LED Grow Light: Effect On Indoor Herb Garden (Basil, Dill, Lettuce)

Does 3000K and 4000K Color Temperature (CCT) Have Different Effect on Basil, Dill, and Lettuce When Growing Indoors?

When growing herbs and vegetables indoors, growers face the dilemma of which LED grow light to choose. Grow lights come in all shapes, sizes, and hardware, including different "CCT", or color temperature, which is measured in Kelvin, K.
Generally speaking, the consensus in the growing community is that low Kelvin, 3000K and below, grows taller plants while high Kelvin, 4000K and above, grows more compact and bushy plants.

As our LEDTonic Q2 LED grow light comes in three different Kelvins: 3000K, 3500K, and 4000K, we decided to test if there are any obvious differences between the 3000K and 4000K spectrum.

We grew basil, dill, and lettuce from seed in pots and containers inside a closet for 45 days. Our little indoor herb and vegetable garden quickly came to life and the entire grow was documented with images and video.

Although the results were a bit underwhelming, we encourage you to watch the video. In short, the differences between our plants (basil, dill, lettuce), were after 45 days marginal. While a more quantitative experiment may have resulted in a more distinct result, our small experiment showed very little difference between 3000K and 4000K spectrum.
Our conclusion is that for hobby growers the choice between 3000K and 4000K will have only a marginal effect on plant growth. In other words, the CCT shouldn't be the main factor when choosing between various grow lights.

Happy farming!

[AMVayanefan]

This test proved that we could grow earth veg in other solar systems. This video was helpful on my home planet of the first Earth colony, on date 2762. Thank you from the future.

[EnchantedPlantQueen]

Awesome video! I just bought a 4000k light to help out a Thai constellation Monstera I was gifted for my birthday. This was a very helpful comparison👍🏻

[SheEsq]

Thank you. I bought lights that adjust up to 4000k for under kitchen cabinets and ended up using others. So i have these and now want to use them for groing a few veg. I keep reading that 4000 is not enough. This video helps me to at least get started. I can move up if I can get the rest of the "system" situated. Not growing for sale, just for salads and soups in Michigan winters. Thanks again.

[yousefalabdrabalnabi]

I'm growing Basil in a hydroponic 27-gallon container. What is my best option for lighting? I'm using GE Grow LED Light Bulb, but my Basil is not doing good and keep getting worst.

[consumiblesasis]

Me encantaron tus videos, el de la comparación de los materiales reflejantes me fue muy útil y de mucha ayuda. Veo algunos comentarios negativos y la verdad espero no los tomes en cuenta porque la mayoria de las personas quieren criticar de forma negativa el trabajo de otros cuando ellos no hacen ni aportan nada. Es una pena que ya no hayas creado contenido nuevo desde ya mucho tiempo atrás porque creo ibas por muy buen camino y tus videos iban siendo cada vez mejores. Espero volver a saber de ti y tus aportaciones en youtube ya que pocas personas hablan de forma tan detallada y minuciosa del manejo de la iluminación en las plantas. Te dejo un abrazo fuerte. Por cierto te escribo en español para que tengas presente que personas de muchos lados en el mundo podrían estarte viendo y encontrando la información que necesitan para sus proyectos. Andrea.

[BState]

Interesting. It would be more interesting to see 3000K vs 6500K.

[guyeshel]

I would really like to know the difference between 3000k to 6000k in tomatoes and such

[lesavoirestunearme-z]

Hey, very interesting and very good video 🙂👍 We can clearly see on these lettuces that a colder color temperature ( higher 450nm wavelength) promotes the production of anthocyanins ( as seen on cannabis with cool color temperature LEDs, or with the addition of 450nm blue or 365-400nm UVA LEDs ), as well as a more stocky structure and higher leaf production. Thank you for this very interesting comparison !

[myshow]

I definitely can see the 4000k produced better results. Better leaf color and more compact growth.
There isnt much difference between 4k and 3k..use 6500k next time and results will be much better

[oystein]

I like these testing videos. My led lights is 4000k.

[jahstafari]

3:90 when plants look like that in my garden i say bad year

[unsaltedorganics]

I’m going to be using my Q2 to start my vegetables for my outdoor garden next year

[jeremycromwellm]

Color temperature is related to PAR light? 3000k will have more red spectrum and 6500k will have more blue spectrum?

[rygoon]

Note you can raise the lights to equal both lights

[mihanivazn]

great video. thanks for your effort. i just planted my first lettuce under 50w 4000k shop led light i got for free. im just not sure how far from canopy to set them up. seeds just yesterday emerged from soil.

[heisenberg]

Hey great video! I would love to see the difference between 400k and say 6500k

[harrypeterson]

Color temp and actual photosynthetically active radiation aren't entirely correlated.
There are two fairly narrow wavelength ranges of light that most effectively produce photosynthesis, one is blue and the other red. Different lights of the same color temp typically have different mixture of those wavelength.

4000k actually falls into what is generally the worst in terms of PAR being not especially high in either the red or blue wavelengths plants need but higher in the green part of the spectrum which is virtually useless to plants. 2700k is typically decently high in the red while 5500k and 6500k are good in the blue region.

[apple-onpq]

its better if you can show the colour spectrum of those light as well.

[Sammyj]

Your plants are leggy. When you start your seeds, have the light 3 to 6 inches from the soil. As the plants grow, raise the light. You will see fuller plants. I have a market garden and I start seeds indoors for spring. Leggy plants are a no go for us. Right when the first leave touches the light, raise 2 inches.
Peace!!!!

[igorfomenko]

Thank you very much, Iooks like your basil suffered from phosphorus deficiency