Demystifying Far-red Light for Growers

Optimizing Growth Beyond the Visible Spectrum

  • Far-red light: Minimally visible region 700-800nm impacts photosynthesis and morphology.
  • Accelerate flowering: Manipulate Pr/Pfr balance with far-red light for earlier blooms in short-day plants.
  • Expanded plants: Trigger shade avoidance with far-red light, encouraging taller plants with larger leaves for better light capture leading to other benefits.
  • Easy integration & experimentation: Far-red light bars offer user-friendly integration. Experiment with timing, intensity, and duration based on your specific plants, environment, and desired outcomes.
  • Far-red tech holds vast potential: Optimized morphology, faster flowering, even influencing cannabinoid production.

Gone are the days of solely relying on the visible light spectrum for optimal plant growth. A hidden realm of light wavelengths, beyond the vibrant hues we perceive, holds immense potential for cultivators: the fascinating world of far-red light. While nearly invisible to our eyes, it plays a crucial role in plant physiology, influencing diverse growth processes and unlocking a treasure trove of benefits for growers of all levels.

Unveiling the Far-Red Spectrum: Beyond Photosynthesis

Our eyes perceive the captivating colors of the visible light spectrum, but plants have a wider sensory range, detecting wavelengths beyond the red end. This minimally visible region, known as far-red light (700-800nm, peaking around 730nm for plant impacts), plays a surprisingly intricate role in plant life.

Far-red is often mislabeled as IR. IR is >780nm and is essentially heat, which has impacts on plants but not because of any photoreceptors. Most LED conversations about IR actually mean far-red light, typically created by 730nm LEDs to fill the 700-750nm region absorbed heavily by activated Phytochrome, which we talk about more below.

Far-red light contributes to photosynthesis more strongly than originally theorized, but is unique in its interaction with a specific photoreceptor called Phytochrome, triggering various responses depending on its presence or absence. Imagine Phytochrome as an orchestra conductor, with far-red light playing the role of a specific instrument, directing the plant’s internal symphony.

A Symphony of Photoreceptors: How Plants “See” Light

Plants perceive light through an orchestra of tiny light-sensitive molecules called photoreceptors. Among these, Phytochrome plays a starring role, existing in two forms: Pr (a ground state which is activated by red light) and Pfr (an excited state which is deactivated by far-red light). In daylength-sensitive plants like cannabis, the delicate balance between Pr and Pfr, and the duration spent in either state, dictates whether the plant remains in its vegetative stage or transitions to flowering.

Accelerating the “Sleep” Signal for Earlier Flowering

As darkness falls, Pfr naturally reverts back to Pr in a gradual process. This shift triggers the plant’s “rest” phase, ultimately leading to flower initiation if the dark period is long enough. The Stratum Far Red Bar, designed to harness the power of 730nm far-red light, specifically targets and accelerates this Pfr to Pr conversion.

Imagine sending a stronger “sleep” signal to your plants. By introducing a relatively short period of far-red light during the last 30-60 minutes of the light cycle and, more importantly, the first 30 minutes of darkness, you essentially mimic the natural dusk transition. This amplified signal translates to earlier and more robust flowering, without necessarily requiring as many hours of continual darkness. Think faster harvests and potentially higher yields – a compelling prospect for any grower.

Shade Avoidance: How Far-Red Light Can Promote Stronger Plants

Picture sunlight filtering through dense foliage, creating shaded areas for your plants. In response, far-red light triggers a fascinating adaptation called shade avoidance. The plants stretch taller and develop larger leaves to capture more light for photosynthesis. This ingenious response can translate to increased yields and greater overall growth. Additionally, far-red light improves airflow and circulation within the canopy, reducing the risk of mold and diseases – think of it as a light shield protecting your plants’ health.

Manipulating Flowering with Far-Red Light for Short-Day Plants

For short-day plants like cannabis, the duration of darkness plays a critical role in triggering flower initiation. Traditionally, growers rely on precise light cycles to mimic natural dusk and dawn conditions. However, far-red light offers a unique tool to manipulate this process. By introducing far-red light during the dark period, growers can effectively trick the plants into sensing an earlier “dusk,” accelerating the transition to the flowering stage. This can translate to faster harvests and potentially higher yields throughout the year.

Beyond Hype: Practical Applications of Far-Red Light in Your Grow

Integrating far-red light technology into your grow setup doesn’t require major changes. Dedicated far-red light bars and far-red light bulbs offer user-friendly solutions, allowing you to harness the power of this invisible spectrum. Consider incorporating far-red light during specific growth stages:

  • Seedlings and young plants: Far-red exposure early in the light cycle encourages beneficial stretching for a more full canopy, laying the foundation for strong future growth from larger leaf areas catching more light.
  • Flowering stage: Introduce far-red light during the last 30-60 minutes of the light cycle and beginning of the dark period to accelerate the transition to flowering for short-day plants. Imagine speeding up the process and witnessing beautiful blooms emerge earlier.
  • Start low, go slow: Begin with low-intensity and/or shorter-duration far-red exposure, gradually increasing to avoid stressing or over-stretching your plants.
  • Distance makes a difference: Maintaining the optimal distance between the bar and plants is crucial. We can help you determine the perfect set-up for your specific crop.

Experimentation is Key with Far-Red Light

Every grow environment is unique, and so is the optimal application of far-red light. Experiment with timing, intensity, and duration based on your:

  • Plant variety: Different strains may respond differently to far-red light.
  • Environment: Factors like temperature, humidity, and existing lighting setup play a role.
  • Desired outcomes: Are you aiming for earlier flowering, improved canopy development, or something else?
  • Monitor and adapt: Far-red light is a tool, not a magic solution. Careful observation and data tracking will help you unlock its full potential.

The Future of Cultivation: Exploring the Potential of Far-Red Light

Far-red light technology is still in its early stages, but its potential is vast and exciting. From optimizing plant morphology and enhancing the onset of flowering to fine-tuning light efficiency and even influencing cannabinoid production, the possibilities are intriguing and require more research to unlock them all.

As research continues, expect even more innovative applications of far-red light emerging in the future, revolutionizing the world of controlled-environment agriculture. Imagine a future where growers have even more precise control over plant growth and development, thanks to the power of the invisible spectrum.

Consult with TotalGrow lighting experts to see if the Stratum Far Red Bar or the Far Red Lullaby Lamp are the right far-red light applications for your specific needs and plant varieties.


Q: Is IR the same as far-red light?

A: Far-red is often mislabeled as IR. IR is >780nm and is essentially heat, which has impacts on plants but not because of any photoreceptors. Most LED conversations about IR actually mean far-red light, typically created by 730nm LEDs to fill the 700-750nm region absorbed heavily by activated phytochrome.

Q: What are the benefits of using far-red light in my grow?

A: Far-red light can offer numerous benefits, including:

  • Earlier and more robust flowering in short-day plants.
  • Improved canopy development.
  • Increased yields and overall growth.
  • Reduced risk of mold and disease.
Q: How do I use far-red light in my grow setup?

A: Dedicated far-red light bars and bulbs are available and offer user-friendly solutions. Consider incorporating far-red light during specific growth stages and start with low intensity and duration, gradually increasing as needed.

Q: Can far-red light damage my plants?

A: Using far-red light responsibly and following recommended guidelines is crucial to avoid stressing your plants. Start low, go slow, and monitor your plants closely for any negative reactions, especially excessive stretching.

Q: Where can I buy far-red light systems?

A: TotalGrow offers the Stratum Far Red Bar, designed to harness the power of 730nm far-red light, specifically targeted to accelerate Pfr to Pr conversion, as well as the Far Red Lullaby Lamp bulb version. Contact us today to discuss your specific requirements and find the perfect setup for your grow.

Jeff Mastin

Director of Lighting Science & Products

For over 12 years, TotalGrow has empowered growers to achieve their full potential. More than just selling lights, Biologist Jeff Mastin crafts customized lighting strategies through data-driven solutions and partnerships with growers, research institutions, and utility companies. This commitment to innovation and partnership ensures TotalGrow clients maximize results and enjoy significant savings. Over 1000 growers have trusted TotalGrow to illuminate their path to success with the latest technology and expert guidance.