Tight buds

That is genetics for a big part... But you could have the lights too far away - with maybe too little power... Some LST might help as well.

Good lights - Led ones above 60watts (real watts) to 240watts in a scale area that goes for 60x60cm to 100x100cm respectively. Also, Fertilization. More P and K from 3week bloom to the end. And good N overall in veggin and the first two weeks of floration. Avoid overwatering or underwatering, search for better watering schedules based on your climate in your region.

Additional P and K during flower will help to create nice, dense buds... If you're using liquid nutrients, you might try adding some General Hydroponics KoolBloom liquid which has an NPK of 0-10-10... they also have a dry formula of this that you use in the last couple of weeks replacing the liquid... but in general, just look for a good PK booster and start using it when the plant goes into flower. Good luck!