Introduction
Ask any greenhouse grower what drives yield, and the answer is usually simple: light. For years, the focus has been on giving plants as much photosynthetically active radiation (PAR) as possible—red and blue being the favorites. But here’s the surprise: there’s another part of the spectrum, just beyond what we see, that can make a big difference.
That’s far red light (700–800 nm). While invisible to us, plants can sense it—and respond in ways that directly impact yield, crop quality, and efficiency.
For high-wire crops like tomatoes, cucumbers, and peppers, far red isn’t just an add-on. It’s becoming a key tool for shaping growth and getting more out of every square meter.
1. What Exactly Is Far Red Light?
Far red sits right past the “visible” PAR range—700–800 nm. You can’t see it, but your plants do. And while it doesn’t directly drive photosynthesis like red or blue light, it acts as a signal that changes how plants grow.
2. Why Plants React to Far Red
Plants have built-in sensors called phytochromes. These detect the ratio of red to far red light. When the ratio tilts toward far red (like when shaded under a canopy), plants respond by stretching taller, expanding leaves, and trying to capture more light.
In the greenhouse, growers can harness this natural response instead of fighting it.
3. Stretch vs. Structure: How Far Red Shapes Crops
For high-wire crops, a little elongation isn’t bad—it’s good. Far red helps:
Tomatoes open up their canopy for better airflow and light penetration.
Cucumbers develop larger leaves, catching more photons per plant.
Peppers find a balance between vegetative growth and fruiting.
The trick is controlled use. Too much Far Red can cause weak stems, but the right dose creates a crop that’s easier to manage and more productive.
4. The Canopy Advantage
Dense high-wire canopies often mean the bottom leaves go unproductive. Far-red helps create more space in the canopy, letting light reach lower leaves. That means healthier plants top-to-bottom—and more uniform fruit development.
5. How Far Red Can Boost Yields
Studies and grower trials point to solid gains:
Tomatoes: 10–15% more fruit weight with FR added.
Cucumbers: more marketable fruits and bigger biomass.
Peppers: up to 20% higher yields, often with better fruit size.
This isn’t just from “more stretch”—it’s also from the Emerson Enhancement Effect, where red + far-red together make photosynthesis more efficient.
6. Fruit Quality Improvements
Beyond yield, Far Red can tweak fruit quality:
Bigger size
Better sugar content (sweeter taste)
Firmer fruits with longer shelf life
For greenhouse growers selling into premium markets, these improvements matter as much as yield.
7. Far Red vs. More PAR: Which Wins?
You could crank up PAR (red/blue) to push growth—but that drives energy costs up fast. Far red works differently: it makes plants use light more efficiently.
In many trials, a small Far Red supplement delivered more biomass per kilowatt-hour compared to just raising PAR.
8. Managing the Balance (Blue, Red, Far Red)
Blue keeps crops compact and strong.
Red drives photosynthesis and flowering.
Far red shapes architecture and enhances red’s efficiency.
It’s about the recipe, not just more light.
9. Risks and Mistakes to Avoid
Too much Far Red = excessive stretching and weaker plants.
Wrong balance with blue/red can backfire.
Crop-specific responses mean you should trial Far Red before scaling.
10. Practical Tips for Using Far Red in Greenhouses
Start small: 5–15% of your total light as far red is typical.
Use tunable spectrum lights to dial in the right ratio.
Consider timed pulses at dusk to influence flowering or stretch.
Track results closely—every crop and setup responds a bit differently.
11. The Future of Far Red Growing
As LEDs become more advanced, growers are gaining precise control over spectrum recipes. Far red is no longer ignored—it’s a core part of modern greenhouse strategies, especially for high-wire crops.
The next wave of innovation will combine Far Red with other spectrum tools to push yields higher, improve quality, and make greenhouse farming more profitable and sustainable.
Conclusion
Far red light might not be visible, but its effects are clear. For plants like tomatoes, cucumbers, and peppers, it helps shape canopies, boost efficiency, and deliver higher yields with better quality. In a competitive market, growers who learn how to use far red effectively can stay one step ahead.