In 2001–2002, he pitched for the Michigan Battle Cats, the Astros Single-A team, going 14–5 with a 3.15 ERA in 35 games (16 starts).

In 2003 and 2004, he pitched primarily for the then Double-A Round Rock Express in the Texas League, where he went 12–5 with a 2.94 ERA in 28 starts with 3 complete games.

He failed to make the major league team out of spring training and spent the year with the Las Vegas 51s in AAA.

In January 2008, the Dodgers sold Houlton's contract to the Fukuoka SoftBank Hawks of the Japanese Pacific League.

However, after blowing three straight saves at the end of May and beginning of June (all in Interleague play), Houlton was demoted to ni-gun.

Reassigned with the number #54 in 2009 and being pegged a starter from the outset as Mahara was finally healthy, Houlton was able to settle into a role early on, a luxury he did not have the previous season.