There is no reason really why you couldn't although it is better used mixed with compost. When watering perlite tends to float though and it is normally recommended you use peat or grit to cover seeds
Quote Perlite may also be used 100% in place of compost- provided that it is kept wet at all times by capillary irrigation or intermittent mist. Sprinkle fine peat over the seeds, and cover with glass or plastic to retain moisture until the seeds have germinated, and then feed.
