Miracle Gro products are NOT for pot. Period. There are many better pot-oriented fertilizers while there are none worse. Those who would advocate for their products here are far outnumbered by more experienced growers.
Feed, water, water. Feed, water, water.
Use 1/2 strength nutrients your first grow (suggested) so if you fertilize accidentally or stupidly you won't be on here sniveling when your plants wilt/spot/drop/cry alligator tears.
In no order of preference:
- Fox Farms
- Advanced Nutrients
- General Hydroponics (never used them but many do and they are affordable)
My advice is above. Do not over-water and do not over-fertilize. All the light you can force and keep the air moving, keep the air moving, keep the air moving. By the way, make sure you keep the air moving.