Need advice please

Hello, yes, you can grow 4 one-gallon plants in that space. It will probably be a bit tight, but it's possible. My experience with FastBuds is that they are generally smaller.

You can definitely grow so many plants in such a small space. If your goal is to grow many plants in a little space. As a beginner, though, you will have your problems. But you will learn from them. It's just not optimal to grow so many plants in such a small area. If I were to grow that many plants in such a small space, I would top each plant, resulting in a total of four side branches becoming main buds. In the end, you would have 12 fat buds. But as a beginner, you will make a lot of mistakes anyway.

I grow 3 in the same size space in 3 gallon pots, I wouldn't try 4, it will not be enough. 2 is comfortable, 3 is a squeeze, 4 would be a nightmare. I do grow them at different stages though, so plant 1, wait 3 weeks plant another, wait three weeks, plant the final seed then continue the cycle as long as you like. Doing it this way, you only really get 1 at full size all the time, the other two are usually coming into stretch or still a seedling whilst the third is in flower and large.

First of all, you can speak in your native language here since the site has an automatic translation feature. I'm currently writing in German myself.

I'm sorry but that's not going to be enough space to even grow one plant and it be comfortable, especially if the breeder is FastBuds, their strains reach full potential so they can get nice-sized. Even with doing LST this still wouldn't be sufficient space for 4 plants, try 120x60x152 cm (24x48x60 inches) this would be perfect.