HOUSTON -- Houston Astros rookie right-hander Lance McCullers pitched so breathlessly on Monday night that it was easy to overlook the cardinal pitching sin he committed in five of his seven innings of quality work.

McCullers capped a stellar month by eluding trouble and the Astros added to their major league-leading total of multi-home run games in their 6-1 win over the Kansas City Royals at Minute Maid Park.

McCullers (4-2) allowed a solo home run to Royals catcher Salvador Perez leading off the seventh, his lone blemish on an otherwise workmanlike ledger. McCullers allowed four hits and two walks while recording six strikeouts, and despite allowing the leadoff batter to reach in the first, second, fifth, sixth and seventh innings, he retired 11 of 12 batters during one key stretch.

"He had a really good breaking ball," Royals designated hitter Lorenzo Cain said of McCullers. "I don't know if it was a slider or curveball. It had a little of both with the action. It had good break on it. It definitely kept us off balance all night."

McCullers closed June with a 2.11 ERA, the lowest ERA in June by an Astros rookie since right-hander Darryl Kyle posted a 1.80 ERA in 1990. In six of his nine starts, McCullers has allowed one earned run or less.

With second baseman Jose Altuve and first baseman Chris Carter clubbing their seventh and 14th home runs, respectively, in the third and fifth innings, the Astros (45-34) improved to 30-3 in games in which they've hit multiple homers. Altuve matched his career high for homers.

The Royals (44-29) played without shortstop Alcides Escobar and first baseman Eric Hosmer, both of whom were sidelined by hand injuries. Kansas City managed just two extra-base hits -- the Perez home run, his 13th, and a leadoff double from center fielder Jarrod Dyson in the first.

Royals right-hander Joe Blanton (2-1) started to scuffle in the second inning, issuing three consecutive walks in that frame as the Astros grabbed a 2-0 lead. When outfielders Preston Tucker and Domingo Santana collected back-to-back RBI singles in the third inning, Blanton departed. He had already surrendered a leadoff hit in a second consecutive frame, this time a solo home run by Altuve for a 3-0 deficit.

"I take pride in not walking guys," Blanton said. "I can't think of too many games where I walked that many guys. You throw some borderline pitches that don't go your way. You throw some chase pitches that they don't swing at. Other than that, trying to fight command issues makes it that kind of day."

Houston upped its lead to 5-0 when Tucker and Santana drove home Luis Valbuena and designated hitter Jon Singleton, saddling Blanton with five earned runs on five hits and four walks over 2 2/3 innings. Over their first combined six plate appearances, Singleton, Tucker and Santana went 2-for-2 with four walks, three RBIs and two runs scored.

"The discipline tonight was excellent," Astros manager A.J. Hinch said. "We didn't swing out of the zone too much, specifically early. You always ask your guys to take whatever they give you and he (Blanton) was nibbling on the plate or just off the plate and we just continued to take our base, take our base."

McCullers handled the prosperity well. He needed 39 pitches to complete his first two innings but followed that bumpy start by facing the minimum over the next three frames, inducing an inning-ending double play grounder from Royals shortstop Christian Colon in fifth.

"It's huge," McCullers said of the early run support. "It allows you to really attack the zone, be relentless in the zone, and gives you a lot of confidence. You want to go deep in the game, especially when you get some runs early because that's when your team is looking for you to back them up because they gave you the runs."

NOTES: Royals SS Alcides Escobar was a late scratch. He suffered a fingernail injury Sunday against the Athletics. Christian Colon replaced Escobar defensively while CF Jarrod Dyson moved from No. 9 to the leadoff spot in the batting order. ... Astros OF Jake Marisnick completed agility drills and continues to progress in dealing with a left hamstring strain that landed him on the 15-day disabled list on June 19. Marisnick will continue to participate in baseball activities and is on target to be sent out for a rehab assignment. ... Royals 1B Eric Hosmer is likely to miss this series after suffering a sprained left ring finger while sliding on Saturday. Hosmer went 0-for-3 on Sunday against the Oakland Athletics before departing after having difficulty throwing the ball and swinging a bat.