Well, you definately need a way to ventilate the grow area and a fan to circulate the air in the grow room. In about 2-3 weeks you will need to feed the plants so that means a good fertilizer, for best results use a hydroponic fertilizer. You may need to get a TDS Pen or some way to measure how much you are feeding the plants, and yes, you will prob need a PH test kit as well. However, if you are growing with soil you can get by without one just make sure that your medium is PH balanced. By this I mean add dolomite lime and you should be alright.

Later on, or sooner depending on strain, you will need something to control odour if your situation requires it. An ozone generator, carbon filter, Bounce sheets, just read up on many ways to do it depending on the size of your grow.