hello my friend
for automatics as their life cycle is predefined, each day of optimized growth counts towards the final yield.
​Your plan to increase to 40% at 50 cm on day 15 is an excellent basis, but here's how to refine your approach based on what we see on your seedlings:
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​Exit from the “Seedling” stage Around 15 days, the plant has generally finished developing its basic root system and begins its vegetative explosion.
​Increased tolerance: At this stage, the leaves are wide enough to withstand higher light intensity without risking immediate burning.
The observation:
The key to success
​When you increase the potency, your plants will “talk” to you in a few hours:
​Sign of satisfaction: The leaves point slightly upwards (at 45°) as if they were trying to “grasp” the light.
​Sign of stress (Taco): If the edges of the leaves fold upwards (as we have seen in other examples), it is because the 40% is still too early or the lamp is too close.
​Distance between nodes: If the stem between each layer of leaves remains short and stubby, your intensity is perfect. If it stretches too much, you can even lower the lamp to 40-45 cm later.
​Little advice
on your current installation
​In your photo, we see that your seedlings are very green and do not look like they are "tiger" (looking for the light), which proves that your current 20% are doing a good job getting started.
​Make sure the temperature under the lamp does not exceed 26-27°C once you go to 40%, as heat increases proportionally to the power of the panel.
​ Your plan is very careful and intelligent. The gradual transition (20% - 40%) is much safer than doubling the intensity all at once.
I hope this will help you. Have a good evening.