touchingpenguins
Don't take this wrong brother, but if you can't get a grasp on an organic grow, you sure as hell don't want to use coco.
Organics is really easy way to grow good quality canna. The biggest problem people have is a "Chemical Grow Mindset". They get caught up in an additive addiction. They think they are not growing properly unless they have 15 things in their compost tea or top dressing. That's not for you or any other organic newbie. With experience, you can add other techniques of growing.
You need just have a full grow with no problems under your belt.
Ya have to start off with quality media. Using the KISS(Keep It simple Stupid) Mindset, I would suggest using Build A Soil and get a water only mix. It probably will need help in flower and most likely too hot for direct plant, that's easy to overcome..............transplant or just plant into a patch of plain potting media. It's an easy method if you're an organic newbie and even more so being a successful organic canna newbie.
Minimalistic organic ingredients:
1. Earthworm castings.........top dress and compost tea.
2. Good quality compost
3. Horticulture Molasses I've used Medina for 30 years $10 gal Simple feed in the water and compost tea
4 Kelp I like Thorvin kelp. Can top dress, but I think best in tea
5. Powdered Yucca........Since you have had problems in watering and dry pockets. Use very sparingly and best used when moisteng your media before you pot it up. You can mix a little in your compost tea AFTER brewing.
Those simple ingredients will grow canna quite well.
Bigger is better on organics. Bigger means more microbes, more roots, more of a buffer for soil temps, soil moisture and soil chemistry.
Learn your pots fully saturated weight. Water S L O W L Y. Water one girl a little and move to another and so on giving time for the water to soak in until they are fully watered.
Try to hit your VPD and the veg and flower stages. As a long time outdoor organic farmer, I've known of VPD, but with no real control of it, it just info. Growing canna is far different.
Know your lights. Learn the specs and make sure not to have too much intensity.
Just a bare bones take on organics. Pay attention to the details and the plant will take care of herself with the environment you gave her.
I hope you find this helpful. I've tried to make it simple as possible, but very effective.