My first grow

[420RPM]

Hi folks!

This is what my three girls look like 13 days after germination.
Growtent 90x90x178 cm, ventilation with carbon filter from Secret Jardin

300W Lumatek LED is 100 cm from plants running at 50%.
Biobizz all mix in 11 liters Airpots.
Northern lights auto from Nirvana seeds
Temperature is about 24 C.
I'am using a small humidifier that keeps everything about 55-60%
I also run a monkey fan on the same timer as the light 18/6

When can I increase light to 100% and start using light fertilization?
As a beginner, I am grateful for any advice.

[Gingerbeard]

100% light at manufacturers recommendations.
I'll say it again: I have seen a number of people in this forum have nutrient issues with Biobizz. It is a hot soil. You seem to have done well with it in that you have not posted about nutrient issues and do not seem to be showing any. Good on you for that!
That being said, you might very well not need to add veg nutes. That's the deal with premixed soils. Unless they say otherwise, they contain nutrients for veg growth, but not so much for flowering. That is fine looking dope for a 13-day old auto. 13 days is not enough to flush enough of the veg nutes to require more than single-digit percent recommended dose of nutrients.
Whatever you choose, keep a good eye out for nutrient burn. It can be difficult to come back from nutrient burn if you can't stop the plant from taking up nutes which would be the case in premixed soil.

[Bluey]

Growing autos with that light in that size tent on an 18/6 schedule probably will never need 100% light if the light is kept the correct distance from the plants. This is the sweet spot that gives the most even light spread.

You'll be at maximum light around half way into flower.

Best to download an app for your phone and use the DLI measurement. A Max of around 40 to 45 should be about right but watch for light burn. I get nute issues, deficiencies, typically before light burn becomes an issue with my setup.

Being your first grow a conservative approach is often best with nute levels and light. Focus on maintaining the correct environment. The manufacturers recommended nute levels are often too high so if you are measuring EC stay around half to a nax of ¾ recommended levels at max.

With that soil you will probably only need bloom nutes after flowers appear, which is what I think Ginge is recommending.

[Gingerbeard]

B-diddy. Why half power? If the light actually outputs 300 watts, that tent is getting 33.3 watts per square foot. Why would you recommend less?
I'm American. Sorry about converting the more pragmatic metric to imperial. Did you know time is metric? We imperialists did to time what Christians did to Paganism by making people think it was our idea.

[Bluey]

Being an auto it will get its DLI over an 18hr period.
Running the light at 65/75/80% will give it 40 odd DLI if it's in the sweet spot and less heat to deal with and the light and driver will last a bit longer and less electricity too.

If it were a photoperiod it would probably need closer to 100%

If time is metric then space must be too and they are neither. Just ask Albert

[Gingerbeard]

I ain't arguing with you because I don't know what DLI is. It just seems counterproductive like giving less nutes. Y'all do it, but I'm sticking to my nugs.
Albert's dead... ran out of time.

[Bluey]

DLI is the measure of how much light a plant gets over a day. Plants can only process so much light in a day period. If you give them more than they can handle in a day they shut down, their branches and leaves droop and it appears they have been overwatered or just go to sleep...they look like how they look in the middle of their dark spell. This is the Daily Light Integral..

If you look up a graph on DLI you will see graphs for different light schedules and intensity measured in PPFD. As an example typically photoperiods in flower that can take 1000PPFD over 12 hours of light equate to 666PPFD over 18 hours of light for an auto giving them the same amount of light over the day, so the same DLI. Big variations in DLI comes down to strain. Sativas can handle much more than indicas in my experience.

Graph below which shows the relationship.

[Bluey]

Graph from this website. Makes for a good read about DLI https://albopepper.com/dli-ppfd-calculator.php

[Gingerbeard]

Read? Booty, my friend, it has been raining all day. I have been doing those rainy-day dabs I have been saving up and ripping my grower's stash from the Razzpergers. I am far too forked up to read for knowledge. But that graph sure is pretty! Colorful and scientificul.
Maybe I'm just lucky. I do autos balls out light and nutes and don't give a hoot about temperature and humidity because I can't do anything more than adjust my fans.