That is very poisonous and your dog need to go to an animal ER. Call them as you are driving and tell them what happen so they can call poison control to figure out treatment.
What If My Dog Drank Miracle Grow?
If your dog drank Miracle Grow, then you need to get off the computer, find an Emergency Vet and get your dog there NOW, or your dog will most likely die. How in the world, did your dog get into Miracle Grow? Things like that, should be kept out of the dogs reach or locked up!