Control DLI in Coco-Grow according to phase

Introduction

In coco cultivation, cannabis plants usually react quickly to changes. This applies not only to irrigation and nutrient supply, but also to the actual light supplied per day. This is where the Daily Light Integral (DLI) is particularly useful. While PPFD only shows how much light per second hits the leaf surface, DLI describes the total amount of light per day in mol/m²/day.

This guide therefore does not deal with general light measurement, lamp comparisons or dynamic dimming, but with the practical question: How do you combine PPFD and lighting duration in Coco-Grow so that a suitable daily light budget is created for each phase?

What DLI does in contrast to PPFD

PPFD measures the current light intensity in µmol/m²/s. This is important, but incomplete. Two setups can have the same PPFD value and still provide a different amount of daylight if the lamps run for different lengths of time.

Example:

• 500 µmol/m²/s at 18 hours will give a different result than
• 500 µmol/m²/s at 12 hours

This is why DLI is a very useful practical value in indoor growing. It combines:

• light intensity
• light duration
• plant phase

The simple formula is:

DLI = PPFD × light hours × 0.0036

Examples:

• 300 PPFD at 18/6 = 19.4 mol/m²/day
• 500 PPFD at 18/6 = 32.4 mol/m²/day
• 800 PPFD at 12/12 = 34.6 mol/m²/day
• 1000 PPFD at 12/12 = 43.2 mol/m²/day

DLI target areas in coco cultivation

In Coco-Grow, these ranges are practical if no CO2 enrichment is used:

Seedlings and very young plants

• Target DLI: about 12-20 mol/m²/day
• Typical at:
• 200-300 PPFD at 18/6
• 150-250 PPFD at 20/4

This is about a soft start. Excessive amounts of daylight can easily lead to unnecessary stress.

Vegetation phase

• Target DLI: about 25-35 mol/m²/day
• Typical at:
• 400-550 PPFD at 18/6
• 350-500 PPFD at 20/4

In Coco, vigorous, compact growth is easily controllable if the DLI is not increased abruptly.

Flowering phase for photoperiodic plants

• Target DLI: about 30-45 mol/m²/day
• Typical at:
• 700-900 PPFD at 12/12
• up to about 1000 PPFD for very well acclimatized plants

Due to the shorter lighting duration in 12/12, the PPFD value must be higher than in vegetation so that the daily light budget remains sufficient.

Plan photoperiodic vs. autoflower correctly

Photoperiodic varieties

Photoperiodic plants are usually planted with:

• 18/6 in vegetation
• 12/12 for flowering

controlled. When switching to flowering, the daily light time drops significantly. Therefore, you should not only change the timer, but also check whether the DLI does not drop too much after the flip.

In practice, it is advisable to gradually increase the PPFD after switching to 12/12 so that the daily light supply remains within a sensible range.

Autoflower varieties

Autoflowers do not require a 12/12 flip. They flower on a timed basis. Often used in coco cultivation:

• 18/6
• 20/4

are often used. Because the light duration remains longer, the same DLI can often be achieved with moderate PPFD. This is an important difference to photoperiodic plants.

How to implement DLI in practice

1. First determine the photoperiod

First determine the light cycle that matches the genetics:

• photoperiodic vegetative: 18/6
• photoperiodic flowering: 12/12
• autoflower: mostly 18/6 or 20/4

2. Then calculate the necessary PPFD

Once the light duration has been determined, select the PPFD so that the DLI target range of the phase is reached. This prevents you from working with unnecessarily high peak values.

3. Increase in stages

Plants react quickly in coco cultivation. Therefore, increase the daily light budget in small steps instead of abruptly. This makes it easier to see whether the plants are processing the additional light properly.

4th phase not to be confused with phase

A good DLI value for vegetation is not automatically suitable for flowering. Especially the change from 18/6 to 12/12 requires a new calculation.

Common mistakes

• Only look at PPFD, not at DLI
• Keep the same PPFD after the 12/12 flip, although this reduces the daylight budget
• Set autoflowers to 12/12 unnecessarily
• Too rapid jumps in the amount of light instead of gradual adjustment
• Mixing phase values and treating seedlings like established flowering plants

Conclusion

DLI is a powerful tool in Coco-Grow because it combines light intensity and lighting duration into a practical indicator. If you plan not just PPFD, but the total daily light supply, you can adjust light cycles more precisely to seedling, vegetation and flowering. Especially in Coco, where plants often react quickly to changes, this way of thinking ensures more controllable and reproducible results.

Pro Tips

• Always calculate DLI with the real light duration.
• Reassess the PPFD after 18/6 to 12/12.
• Do not switch autoflowers to 12/12 for flowering.
• Increase the lighting budget in phases instead of abruptly.
• Use DLI as the daily target, PPFD as the control variable.