question about NPK

Hello, I want to know if the fertilizer for green houseplants is good for vegetative grow of marijuana? It is 8:6:5 fertilizer with micronutrients. And when to stop using this fertilizer, and change it with the flowering fert?

Short answer is :Yes. Is it the best...NO. If you plants are a few weeks old you could start with 1/4 strength dosage. A ratio to closely mimic is 3-1-2 during vegging cycle. You change to flowering nutes after your light cycle changes to 12/12. There you can up the "P" aspect or your nutes or look for a "bloom" for your girls.

8-6-5 is an all purpose year round fertilizer. It will work and you'll be able to use it from veg to flower. During veg your plant will use N. During flower it will use the P&K. That has both, which is why you can use it year round. Some gardeners however grow the same strain repeatedly and like to dial in the nutrients to a near science. When your doing that you want a veg fertilizer and a flower fertilizer. Basically x-0-0 for veg, and 0-x-x for flower. X being any number you want. The number is a ratio, and means percent per weight. So 1-0-0 is the same as 10-0-0 or 20-0-0. The difference is the concentrations. Think Tide regular vs Tide Concentrated. Same stuff, you just use less of it.

Well said sir, well said.

I know a lot about fertilizers and that stuff, I'm studying it. I just want to ask a experienced growers for advice.
Also, my plant is now about 20-30cm long, and I don't know if it will arrive to flowering, because of the late sow period...

It will flower, but because it was sowed later it won't grow as large. However, for personal consumption you will still do okay. Here in Southern California where the daylight is 14 hours, I have one to two more months to put my vegging plants outside to flower.

Happy growing,

- Vin

Thanks.
It is better not to grow very large, because of the neighbours
I can't believe how roots are developing fast, for a week they took over all the pot, huh...