If you are using organic soil or an organic medium (like Coco-Loco) with organic liquid/dry fertilizer- you should be fine with just watering to the point of soaking the entire pot with no run off. But if you are using organic soil with bottled non organic nutes- you can still have a build up of salts that will most likely need to be flushed out at some point. Usually halfway through the grow as they transition into flowering. I have skipped the flush once or twice before and had some serious issues with leftover fertilizer/salts affecting my plants. Something else to keep in mind when using bottled non organic nutes in an organic medium is that often times the nutes kill off the healthy, beneficial micro/macro bacteria that you are trying to foster in your root zone. So really, it’s bottled non organic nutes and whatever medium you choose or it’s all organic nutes with all organic soil. It’s all or nothing with organics as it’s all about protecting the valuable microbial life within the soil/root zone. Hope this helps!