3000k vs 4000k Grow Light – Which is Good for Growing Plants

(Last Updated On: November 8, 2021)
3000k vs 4000k Grow Light

You need to choose the right type of light to get the best results from your indoor gardens. When it comes to grow lights, many people have a question: 3000k vs 4000k grow light – which is good for growing plants?

The answer depends on the type of plant you are looking to grow.

If you want to maximize the growth of your flowering plants, then the 4000K grow Lights will be better. If you want to increase photosynthesis and produce more vegetables or leafy greens then 3000K lights will be best.

But before we get into the good part, let’s learn some useful stuff.

What is the color spectrum?

The different colors on the visible spectrum are Red, Orange, Yellow, Green Blue and Violet. When light waves hit an object, it absorbs some colors and reflects others. The color that is absorbed will depend on the chemical makeup of the object.

If a banana is placed in a box that allows only green light to pass through, the banana will appear black because the yellow pigment found in bananas absorbs the green light.

The color spectrum is what makes every object look just that- an object! Without different colors, everywhere you looked would be the same color.

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Why is the Color Spectrum Important for Growing Plants?

In a plant’s natural environment, they encounter a vast array of colors in the sunlight. Sunlight has a specific color spectrum depending on how it reacts with the earth’s atmosphere. A large portion of light is reflected from the water molecules and dust particles in the air, thus creating different wavelengths.

color spectrum

The main bands of visible light that contribute to photosynthesis are:

Red (620 – 700 nm) which is critical for Chlorophyll A. This is the pigment that gives plants their green color and absorbs most strongly in red and blue spectrums.

Blue (400 – 500 nm) which is necessary for Chlorophyll A and C. It also aids in absorbing UV light.

Near Infrared (700 – 1400 nm) which enables the absorption of more light and heat energy to raise internal temperature, allowing a plant’s enzymes to react faster. It also activates Chlorophyll A and C.

Far Infrared (1,400 – 3,000 nm) which is associated with energy and increased growth. It also assists in hastening germination and the rooting process.

UV light (100 – 400 nm) which aids in triggering biochemical pathways such as Phytochrome Response that travels via a protein called “UFGT” (Ubiquitin-Favor germinating and Gametogenesis 1). This protein is necessary for the movement of Chloroplasts along the cell. It also converts CO2 to sugar, stimulates enzymes which aid in photosynthesis, seed growth and chlorophyll development.

The color spectrum of light inside indoor gardens can either make or break plant growth. This is because the color spectrum of artificial light tends to be incomplete compared to sunlight.

For example, during daylight hours, plants are exposed to red and blue spectrums when receiving direct sunlight. Green leaves appear green because this is the color they reflect. A lack of one or more parts of the spectrum can have negative effects on plant growth.

Hence, it is important to get good quality grow lights with the right amount of K so you can fulfill your growth targets.

Differences Between 3000K and 4000K Grow Light?

Differences Between 3000K and 4000K Grow Light

A lot of people are interested in how much electricity their grow light consumes, but many don’t know that you should be just as concerned about the color temperature. The color temperature is expressed in Degrees Kelvin (K) and different types of LEDs have different degrees of color variation.

You may have heard of “warm” light bulbs that you can purchase for your house. These actually just filter out the blue wavelengths, leaving behind red and yellow colors which you probably associate with feeling warm.

This is how home lighting differs from grow lights; while growers want to focus on giving their plants the PAR (photosynthetic active radiation) wavelengths of light, home lighting is intended to give off a cozy feeling – and it can lead you astray when you try to apply this concept to plant grow lights.

 Read More: Can Any LED Light be Used as A Grow Light

Color temperature is measured using the Kelvin (K) scale and it measures how much red and blue light are present in the color. The sun emits light that has equal parts blue and red light, which is why the sun’s color temperature hovers around 5800K.

If you were to look into a grow light that had an equal balance of blue and red, it would have a color temperature of 3000K – very similar to the sunlight at noon on a sunny day! Most grow lights vary from this standard however, and will give off more blue or yellow/red light depending on the strength of the bin.

The difference between 3000K and 4000K grow lights is usually not significant. In fact, it can be hard to tell the difference between the two at all. The real problem is that 3000K and 4000K lights exist in different kinds of grow lights.

4000K grow lights have a higher proportion of blue LED diodes than other lights, so they have a “cooler” appearance. If you compare the light from an HPS grow light to that of a LED with 4000K color temperature, you would notice that the HPS gives off more yellow/red tones and is considered warmer.

3000K grow lights are the most commonly used grow lights because they balance between blue and red, which is why their light appears white to the naked eye. This is also why 3000K grow lights are considered full spectrum.

Blue light, on the other hand, has a high level of effectiveness for photosynthesis and penetrates plant leaves very well, but it is virtually nonexistent during the day.

This is why blue light appears to be so effective at growing plants indoors – by combining red and blue LEDs in an indoor grow environment, growers can ensure that their plants are receiving just enough energy for photosynthesis without wasting any.

Because 4000K grow lights contain a higher proportion of blue light than other grow lights, they tend to be the better option for growing plants indoors.

However, you will need a higher wattage and more powerful LED diodes in order to produce enough PAR for your garden. Plants that only need 3000K can benefit from lower power consumption by using less powerful LEDs with a color temperature of 3000K.

 Read More: 5000k vs 6500k for plants

3000K vs 4000K Grow Light- which should you pick?

3000K vs 4000K grow light

In general, plants that need a lot of blue lights will thrive under 3000K while those needing more reds should do well with 4000K grow lights.

However, this isn’t always true so it’s important to know exactly which type of plant you’re growing before making your purchase!

It also helps to understand how much energy you’ll save in comparison with traditional HID bulbs! Since LEDs last longer than their predecessors they end up saving a good deal on replacement costs as well as electricity usage over time.

Of course, different models vary widely in terms of energy consumption so it’s important to do careful research before making a purchase.

3000K LED grow lights are entering a whole separate market from 4000K LEDs. They have a completely different quality of light, and they’re better for completely different uses.

The best way to decide if you need a 3000K or 4000K light is to know what kind of light your plant needs.

3000K or 4000K grow light

4000K grow lights produce a blue-tinted white light, and they come from the “white” LED (also known as “cool white”) family. These lights are excellent for cloning and vegetative growth, but they aren’t very good for flowering.

3000K grow lights produce a golden-tinted white light (much like the metal halide bulbs commonly used in the vegging phase of growing).

These lights work well for both vegetative and flowering stages, but not as well to promote cloning. As a rule of thumb, you’ll want to make sure your clones and vegetative plants get the 3000K grow lights.

And now that we’ve got all those technical details out of the way, let’s talk about what they actually look like:

Unfortunately for consumers, most manufacturers don’t put much effort into describing what their grow lights look like to the human eye. You’ll have to do some research on your own, but here are just a few examples of the different kinds of white light you might see in various grow lights:

 Read More: Purple Grow Light vs White Light

Best Kelvin for growing plants using LED grow lights

For growing plants indoors, you need a specific wavelength of light that can accurately be called “the best” for growing plants.

There is really no such thing as the best kelvin (or color) for growing plants. You can grow plants in any light, but if you want to use only one source of light instead of supplementing with sunlight, your choice becomes very important.

Plants grown in full-spectrum white lights produce more biomass than when they are grown in sunlight. Blue light is very important for photosynthesis and red is a close second, but other wavelengths also play a role.

Red light has been shown to be necessary for normal plant development during the early stages of growth. So, blue and red lights should be used in greater amounts.

 Read More: Full Spectrum LED Vs Red And Blue

The best kelvin for growing plants indoors using grow lights is therefore a white one with red. This would be the most efficient since there are no gaps that are left unfilled.

Nowadays, it’s possible to find LED grow lights which can produce any wavelength of light so they may even be used without sunlight. LED grow lights can be set to produce a specific colour or use a mix of colours. These are becoming very popular for growing plants indoors and many people have been very happy with their results.

There’s also the possibility of using both sunlight and artificial light sources to get the most out of your garden, especially if you live in an area where sunlight isn’t as abundant as you’d like.



Can I put a grow light in a regular lamp?

Yes. You don’t need special fixtures for grow lights although they are recommended. Grow lights are available in the size of regular bulbs. Grow lights are more expensive typically but they come in the same wattage and incur the same running costs. It’s important that you set the lights close to the plants, preferably within a couple inches.

Is it ok to leave a grow light on all the time?

Yes, it is totally fine to leave the lamp on all of the time. The only reason you would want to turn off a light would be to water or work on your plants. It is important though that the light is at the right height over the plants so they are getting direct hot light. If it is getting indirect light, the plants will grow long and spindly.

 Read More: Can You Leave Grow Lights On 24 Hours A Day

Are white LED lights better at growing plants?

The short answer: probably not.

Energy-efficient white LEDs typically emit a broad spectrum of visible white light using blue LEDs with phosphors , which cause them to emit light efficiently. Although the spectrum of this light is often comparable to sunlight, it is less efficient for plant growth than narrow band spectrums that target photosynthesis more directly.

Good LED grow lights can actually mimic the effect of natural sunlight on plants (blue + red = sun). But some models (like many white LEDs) don’t do this. So, if you need your plants to grow strong and with lots of leaves, choose a LED grow light that has the following:

– A narrow spectrum in the blue and red range (the best option is a customised spectrum according to what your plants need) – An adjustable light intensity with the use of a dimmable model (some plants like high-intensity light, and others prefer low-intensity)

– A design that allows you to raise and lower the height of the light over your plants to make sure they get enough light for their different growth stages.

Final Words

LED grow light temperature is an important consideration. You cannot overlook it if you want your plants to grow properly. In general, 3000K lights are more versatile but they don’t work for cloning. On the other hand, during the vegetative stage and for cloning purposes, 4000K lights are excellent.

So, the answer to the question ‘3000k vs 4000k grow light – which is good for growing plants?’ is- the type of light you require will change depending on your requirements. So, none of these lights are bad. They just need to be used properly.

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