Use Far Red specifically for daily margin control

## Introduction

**Far Red** in the range around **730 nm** is a special light control tool. It is **not** used to replace the main lighting, to bring more PPFD onto the surface or simply to make classic flowering spectra "redder". Its main benefit lies in the **signaling effect on the plant's phytochrome system**.

This guide therefore deals **exclusively** with the targeted use of **Far Red for daytime edge control** in indoor growing. The topic is clearly different from general spectrum guides, PPFD tables or light cycle basics.

## What Far Red actually does in cannabis grow

Cannabis reacts not only to the amount of light, but also to its **spectral composition**. Particularly important is the ratio between:

- **Red light** in the range around **660 nm**

- **Far Red** in the range around **730 nm**

The plant uses the **phytochrome system** to recognize whether "daylight" or "end of day/shade" is being signaled. Far Red shifts the phytochrome state more quickly towards the night signal. This is precisely why Far Red is mainly used in practice as **End-of-Day-Far-Red**.

Important:

- Far Red is **not a substitute** for a correct light cycle.

- Far Red turns a wrong photoperiod **not a correct one**.

- Autoflower strains do **not need a 12/12 flip**; Far Red is only an optional control tool, not a flowering trigger in the classic sense.

## Useful areas of application

Far Red is most useful in setups where:

- the main light is already properly planned,

- the photoperiod runs precisely on a timer,

- a separate, switchable Far Red module is available,

- you want to work specifically with light signals instead of more intensity.

Far Red is **not a must-have tool for beginners**. Anyone who does not yet have stable basic lighting will benefit considerably more from correct main lighting, a suitable photoperiod and clean surface illumination.

## Practical application: End-of-Day-Far-Red

The most common method is a **short Far-Red window directly after switching off the main light**. The aim is to signal a clear end of day to the plant.

### This is how it is implemented

- Use a **separately switchable 730 nm module**.

- Let the main light end regularly.

- Then switch on only Far Red for a short time window.

- Keep this window **consistently the same every day**.

### Typical practice duration

In practice, **short intervals of around 5 to 15 minutes** are usually used. Longer durations are not automatically better and often only increase complexity without any clear additional benefit.

## What Far Red should not do

Far Red is often used incorrectly. Avoid these mistakes:

- **Do not** plan as an additional main light source

- **Do not** calculate to increase the PPFD

- **Not** as a replacement for red light in the PAR range

- **Do not** switch on in the middle of the dark phase

- **Do not** operate uncontrolled together with general spectrum boosters

The last point in particular is important: an improperly tuned spectrum with a permanently high far-red component can promote undesirable **stretching reactions** because the plant is more likely to perceive a shadow or competition signal.

## Differences between vegetation and flowering phase

### Vegetation phase

In the vegetation phase, Far Red should usually be used with **restraint**. Too much signal in the direction of shade avoidance can unnecessarily stretch the plants. If at all, then only very selectively and with clear observation of the internode spacing.

### Flowering phase for photoperiodic varieties

During flowering, End-of-Day-Far-Red can be used to mark the end of the day in a more defined way. However, the **correct 12/12 cycle** with an uninterrupted dark phase remains decisive. Far Red does not replace this requirement.

### Autoflower

Autoflower plants flower **dependently of age**, not because of 12/12. Far Red can be used here at most as a subtle light signal, but is **not necessary** to initiate flowering.

## Choice of technique

Pay attention to the hardware:

- clearly labeled **730 nm emitters**

- **separate switchability** from the main panel

- reproducible timer control

- No mixing with undefined "bloom boost" switches without spectral information

A system in which Far Red can be activated **independently** of the full spectrum is ideal. This is the only way to test the daily edge control properly.

## Common errors

- Allowing Far Red to run for the entire light day

- Confusing 660 nm and 730 nm

- Consider Far Red as a yield guarantee

- Use irregular switch-on times

- mistakenly expect a 12/12 effect with autoflowers

## Conclusion

**Far Red for end-of-day control** is a specialized tool for advanced indoor growers. Used correctly, it can make the **light signal at the end of the day more precise**. The key lies in a **short, separate, constant application around 730 nm**. Those using Far Red should not think of it as a main light, but as a **targeted phytochromic pulse**.

## Pro Tips

- Only use Far Red with a separate timer.

- Pay attention to the manufacturer's genuine 730 nm specifications.

- Start with short end-of-day windows.

- Never evaluate Far Red on PPFD values alone.

- Autoflowers do not need a 12/12 flip to flower.