BOSTON — David Ortiz hit his first homer of the season while going 3-for-4 with three runs and two RBIs as the Boston Red Sox beat the Houston Astros 7-2 at Fenway Park on Thursday night.

Ortiz, activated from the disabled list last weekend after missing the season’s first 15 games due to heel problems, is batting .550 (11-for-20) through five games.

“I’ve been putting good swings on the ball and things (have) been happening,” Ortiz said. “Some pitches when you are locked (in) at the plate, they’re not going to be hit, they’re going to be homers. And when you’re not (locked in) sometimes they’re going to be outs, sometimes they’re going to be rollovers, sometimes they’re going to be just singles. So it’s a process.”

Boston right-hander Clay Buchholz (5-0) struck out 10 in 7 2/3 innings. He allowed two runs on six hits and two walks, but he saw his ERA rise from 0.90 to 1.19 ERA. Buchholz leads the majors in win and ranks third in ERA.

“From the fourth inning on he got into a much better rhythm, became much more efficient,” said Red Sox manager John Farrell. “Had the benefit of the four runs in the first inning but he gave us what we needed, and that was a night to go deep in the game by a starter to give our back end guys a night of rest. And the offense gave us just enough support to get through it. So very solid outing from Clay once again.”

Astros right-hander Phillip Humber (0-5) lasted just 4 2/3 innings, giving up seven runs on 10 hits. He leads the majors in losses.

“I’m just not making good pitches,” Humber said. “It’s not fun to go out there and get hit around like that. If I had an answer I would have done something different. Give credit to their hitters, they’ve got good hitters and didn’t miss the pitches they should hit. It was pathetic. I didn’t give our team a chance to win. Obviously the time before and today.”

“It’s definitely not fun,” said Astros manager Bo Porter. “It’s hard when you fall behind early in a game against one of the better pitchers in our league. You’re on the road and you’re fighting an uphill battle. “

The Red Sox jumped on Humber for four runs in the first inning. With one out, Daniel Nava walked, took second on a passed ball and scored on Dustin Pedroia’s single to center field. Ortiz’s single to right scored Pedroia. After Mike Napoli struck out, Mike Carp double to right, scoring Ortiz, and Jarrod Saltalamacchia’s single to right scored Carp, giving Boston a 4-0 lead.

The Astros got a run in the second on Matt Dominguez’s double-play grounder and another in the third on Jason Castro’s two-out RBI single.

Ortiz, who started the season on the disabled list with Achilles and heel ailments, led off the third with a home run, his first of the season, to straightaway center field.

Saltalamacchia hit an RBI single in the fifth, and Will Middlebrooks added a run-scoring double in the inning.

Red Sox right-hander Daniel Bard, who was called up from Double-A Portland on Wednesday, made his season debut, pitching a scoreless ninth inning.

NOTES: Red Sox RF Shane Victorino was not in the starting lineup because of lower back pain. He is day-to-day. … Boston RHP John Lackey is expected to be activated from the disabled list to start Sunday. Lackey has been out since April 7 due to a right biceps strain. … The Red Sox called up C Ryan Lavarnway from Triple-A Pawtucket to take the roster spot of RHP Alfredo Aceves, who was optioned to Pawtucket after Wednesday’s game. Lavarnway is expected to be sent back to Pawtucket when Lackey is activated. … Houston 2B Jose Altuve entered Thursday’s game leading the major leagues with 30 hits. He had hit safely in nine of his last 10 games and went 1-for-4 on Thursday. … It was a homecoming of sorts for first baseman Carlos Pena, who is from Haverhill, Mass., and went to Northeastern University in Boston.