Yes always make sure the plant is rootbound. Saturate the rootball and soil let it stand for 5 min then carefully sqeeze the sides of the pot the carefully pop out the rootball upside down into your other hand. Then put it a corner of the room that doesn't have direct light for a week or so.
They need more P and K.
Phosphorus (P)
Also identified by slow growth, leaves will become a very dark green or purple color and may have red or purple veins. Leaves may be quite small and possibly deformed. Using a high P fertilizer should correct the problem.
Potassium (K)
This is tricky...
When you use coco designed to grow dope and hydro nutes you wont get these ph issues soils get. Your ph is too low and as you can see by the chart your uptake of N,P, and cal ,mag is inhibited.
Its not a good thing thats for sure. If you have green leaves near buds at harvest the buds are denser and heavier and look a lot better. The yellow leaf into the bud really affects the finished product. Use a medium next time that doesn't hold onto salt like yours does.