They will definately be at least 4 ft tall for sure. You figure they will double in height by the end of flowering. So if they are 2 ft by flowering time they will most likely hit 4ft.All my babies are 10 inches or taller. full sun all day hoping that they get 4-5 feet by the end of the year. think it will happen?
amend it with High quality potting soil (such as happy frog) and Perlite, you will see much better results than just pure coco peat.Mixed with sand, compost and fertilizer to make good quality potting soil. Coco peat generally has an acidity in the range of pH - 5.5 to 6.5. It is a little on the acidic side for some plants, but many popular plants can tolerate this pH range.
in other words, thisSoil, perlite, coco coir would be a great outdoor medium imhumbleo