Do not, repeat, do not, use any Miracle Grow product to grow autos. They all contain slow release nutrients, even their perlite, which will really screw with autos. You will just end up chasing one problem after another with it. Get yourself a good soil mix like Pro Mix, Sunshine #4 or any of a variety of good ones that are available. You will also need, at the very least, a good liquid pH tester. Maintain the proper pH is imperative for good auto growth and without one, you'll only be guessing. If you run into any issues and seek our help, it's likely one of the first questions you will be asked is what the pH is of your feeds and your run off.