Outdoor Coco?

So basically i am asking this question because i have a few of those reptile exo-terra coconut husk fibre bricks laying around and they say they pack about 8 litres of substrate each. This would potentially be great for backpacking substrate, but the thing is you'd need nutrients right?
How often would you have to feed?
Lets say its impractical to get to the grow site. How would you go about keeping your plants alive? Time release ferts?

I'm no pro but I would say yes to time release ferts and also make sure it's not in a areas where it gets to dry or where it's to hot don't want them to get heat stress or be under watered.