How windy is the area you're growing in?
You can encourage your plant to produce more dense buds if you aim some wind at them with either a fan or by putting them in a naturally windier spot. You could also try to build a sort of wind tunnel. I've had luck doing this with 1 of my plants, by propping up 2 pieces of wood on either side of the plant. The pieces of wood I used were about 4 feet tall, 5 feet wide, and about 1 1/2 inches thick. I propped them up with rocks on either side. This created a kind of wind tunnel which allowed my plant to grow thicker stems