The light you listed would do the job, but you are in a closet and 600watts in the that small of an area you better be air cooling. If you do decide to go with a 600w then get a reflector that can be aircooled, the one you had listed was a bat wing (you can't air cool) also if you are using a 600w go with the Philips Son-T has more lumens then the hortilux. If 400w go with hortilux. Now you need to look at a flou. for you seedlings and cuttings. You can go to homedepot for this one, standard or plant spec flou. are ok.

green leaves