Soil + coco mix with added perlite and/or hydro corn. Then put slow release nutes in it. Biotabs offers a good easy to use product line, but ofc you could make something your own. The point would be to not let the slow release nutes start to release anything in the soil when you first plant your plant, and perhaps make it lighter on top of the soil than on the bottom(with biotabs it doesent matter). This way you get light nutrient soil in the beginning that continues to release nutrients through the grow cycle and allows you to feed just water, if you dont care to add stuff like kelp with the water, but no NPK nutes required. If you make your own soil and you make it too light, you can top feed more dry nutes or start to add nutes in the water. It might be a good idea to add some PK at some point of the flowering. Biotabs has liquid PK that also has food for microbes, vitamins etc added to it. Naturally you can use any, but if you use biotabs, it goes nicely with the other products.
If you do make your own, you might want to use less nitrogen and focus more on making good soil for flowering with some nitrogen, because autos dont need it as much as photos, as they start to flower so small. Im sure some people have made good auto recipes, but dont just take any recipe made for photos.
