A shading/transparency issue on a shower

I recommend trying to use the glass shader in Sims 4 Studio under tools - modding - Glass Shader. Using the glass shader should remove the black areas around the edges of your flowers/herbs. If that still doesn't work for you please upload the package file so I can take a look for you. I have only ever used the glass shader for cas items so I am unsure if it will work for objects but it is still worth trying.