He forgot a step that works like a charm for me....
Scrape the sides of the stem and split the stem at the bottom before dipping in rooting hormone. This make the enitre stem, inside, out, and the tip of the bottom explode with roots.
I also keep my clones under a couple of 18 watt T12 5000k fluoros 24/0 for 1-2 weeks before transplanting.