You and your plants will be big on Miracle-Gro Potting Mix because of what it can do. For you: Plants with more blooms and more colour vs unfed plants, For them: Grows Plants Twice as Big. There’s another big reason to use Miracle-Gro Potting Mix for all your indoor and outdoor container plants: Miracle-Gro Plant Food is in the mix. Feeds for up to 6 months. Now that’s how to make a big difference with a little potting mix.