You might even try just two to four bags of good 'pot' soil, depending on how big of a hole you dig (the bigger the better). It's always best to eliminate variables when you're new to growing and the best way to start is to begin with high quality organic soil. When in doubt, KEEP IT SIMPLE. Good soil, quality organic Grow nutes, some Cal/MG for root development, then Bloom nutes when the bud's start forming. Keep an eye out for and kill any pests along the way, don't remove so many leaves next time, and you'll have 6 - 8ft bushes next year and several ounces of quality buds.
I agree with CoC, you might as well harvest what you can now. You should get an ounce or so of smokeable bud which is nothing to sneeze at. It's a learning experience you can apply to next year's harvest, and get stoned at the same time. Best of luck next year!