I just remember that the render type needs to register to mod bus. In this case, crops and flowers should use RenderType.getCutOut() in RenderTypeLookUp.setRenderLayer() method. I register my blocks in GensokyoOntology.java.
GensokyoOntology.java:
@Mod.EventBusSubscriber(bus = Mod.EventBusSubscriber.Bus.MOD,value = Dist.CLIENT)
public static class RenderTypeRegistry {
@SubscribeEvent
public static void onRenderTypeSetUp(FMLClientSetupEvent event){
// Render transparent textures to block model like #cross and crop
event.enqueueWork(() -> {
RenderTypeLookup.setRenderLayer(BlockRegistry.LYCORIS_RADIATA.get(),
RenderType.getCutout());
RenderTypeLookup.setRenderLayer(BlockRegistry.ONION_CROP_BLOCK.get(),
RenderType.getCutout());
});
}