"There was not anything that would lead the human thought to go to, 'Mmm, I see some things looming around the corner.' No. It was all beautiful and butterflies when we were around her," Hardwick said in an interview Thursday.
Houston starred in and was executive producer of the remake about three sisters who form a Motown-era singing group in Detroit. She plays the girls' mother, and Hardwick's character falls for one of her daughters.
Houston died in Beverly Hills, Calif., on Feb. 11 at age 48. Filming for "Sparkle" had already wrapped when the singer accidentally drowned in a hotel room bathtub on the eve of the Grammy Awards. Authorities said her death was complicated by cocaine use and heart disease.
Hardwick remembers Houston as approachable, silly, funny and quick-witted with the cast of "Sparkle," which includes Cee Lo Green, Mike Epps and Jordin Sparks.
"She very much was reachable and palpable and tangible and you could touch her and talk about whatever," he said.
Hardwick believes the film, which took Houston 12 years to bring to the big screen, is a fitting homage to the iconic performer and actress.
"It's a passion project for Whitney," he said. "She put all of that energy into it. So at least we have a bit of her passion left on the field, so to speak, before life took her."
Hardwick's credits also include the 2010 movie "For Colored Girls."
"Sparkle" opens in theaters Aug. 17.