For the last year we have been using recycled coconut coir for our wicking bed growing medium. This coir was used to start seeds in our commercial aquaponics operation then sent through the worm bin after harvest. The worms ate all the roots leaving perfectly good coir behind that is enhanced with castings. We found out with some experimentation that this recycled coir will grow great root crops. We are interested to learn what other medias you are using and why.
Wow. Amazing idea. Thank you for sharing your creativity.
Wicking beds can use dirt or potting soil as a planting media. We are using recycled coir because we had it already. The coir allows perfect carrots to grow. We have grown carrots in dirt and sand but many of them end up "Frankenstein claws". If the tap root hits a rock or hard spot it can split and do strange things. We have had no such issues with the coir.
Yes, I remember your discussion on growing carrots in cinder beds. We have a bunch of coir/vermiculite mix that we've just been dumping in our compost pile, but we've been meaning to use that to grow root crops since we found an Okinawan potato growing on its own very nicely in a spare tub of the mix. I'll describe what I had planned in your design discussion. Again, thanks for sharing.
My coir has vermiculite in it too(70%coir & 30% vermiculite). The coir is amazing stuff as it does not break down very easily. Some of our coir is more than 2 years old now and has grown multiple crops and gone through worm bin cycles.