There was nothing on the bag claiming slow release. Plants were doing great on veg, getting bushy very fast and responding to defoliation pretty well. After 30 days of flower I started noticing very slow growth, no trichs, buds not fattening and leaves getting darker every day. After trying every solution users pointed on posts, I decided to have a look at the soil, which was the only thing I didn't really looked into, and found out it's just compost and not potting mix. When I realized that I said Bingo! That's it! I even removed my clone from the pot, tried to remove as much compost as I could and changed it to REAL potting mix 2 days ago. Hopefully she'll not go the same way as the mother with this change.