My experience, albeit limited, has indicated that it's not a good idea to grow in pure coco. The seedling mix should be either 50/50 coco/perlite or 1/3 coco, 1/3 perlite, 1/3 wormcastings. I would recommend starting over with a better soil mix if possible, or perhaps just transplant your seedling into a new mix without disturbing the root.