If you only have a 150w HPS you should transplant into 2 or 3 gal containers today, let them root for a week or 2, and flower them. Buy real soil, not miracle grow, don't be cheap. You want to flower and crop these things as small as possible. 3 gallon buckets are what i would usually suggest, but 5 plants is a lot for 150hps. Are they fem seeds? If not you should throw them into 3 gal buckets, because you may only get 2 or 3 females out of the bunch.
Nutrients are a must, get a starter pack from technaflora, it has everything you need for 35 bucks. Everything. And it is fantastic. Get a PPM meter and PH meter if you can afford both or a combo, if not get at least the PPM meter and some test papers, they sell a cheap test kit, but it is only as accurate as your eye is for color.