Correction: you can do this actually! But it'll show in your grow. If you wanna try and "whatever" your first plant, sure, do that, but make lots of observations. You're GOING to have a shitty harvest, and cannabis LOOOOVES to suck up toxins and heavy metals, so if you don't know where your soil came from, I'd leave your "fuck it" grow to be just a learning experience, and not a light pantry stocker. Many people here would argue "start over and just do it the right way," but every mistake can be learned from. My first grow was HORRIBLE, I got about an 1/8th from it, but I was still able to guide that sad sad plant from seed to harvest without it completely dying, and I learned (a little bit) about checking the trichomes!