Can I use fertilizer in my Oyas?
We say don’t. Though the jury is out on whether this will work or not, we think it’s best not to add fertilizer to your Oyas.
Theoretically, if the fertilizer you are using is completely water soluble (dissolves entirely in the water) it should work. But the tight pores of the terracotta will act as a filter for any of the larger particles, potentially serving as a source of clogging.
And really, how often do you need to fertilize? Make that your surface watering exception.