I recommend the two books, I Can Become a God by Planting and Valkyrie of the Stars, to you. They were all set in the Interstellar Era and described the story of the protagonist becoming stronger and stronger because of cultivation. " I Can Become a God by Planting " mainly told the story of a person who gained great power by planting special plants, while " Valkyrie of the Stars " described a female protagonist who constantly improved her strength through cultivation and fought many enemies. I hope you like my recommendation.