Instructions for Grow Bag Instructions for Grow Bag Day 1: Remove the wrapper from grow bag . Place bag in a bucket of water.Leave overnight to ensure the soil and bag are fully saturated. Day 2: Take the hessian bag out of the water and let it drain for a few minutes. Cut open the top of the substrate mix bag .Place the bag in a sunny spot. Day 3: Depending on the weather make sure you put the bag every 2 day in a bucket of water for 10 min.