https://www.mangago.zone/read-manga/hunter_world_s_gardener/
This is the only one I know
Not isekai but 'Country Diary' had the gardening theme
Not sure if these fit the bill
https://www.mangago.zone/read-manga/i_grew_the_greatest_home_garden_with_my_op_cultivation_skill/
https://www.mangago.zone/read-manga/i_found_myself_with_the_largest_production_base_on_the_continent/
https://www.mangago.zone/read-manga/isekai_de_tochi_o_katte_noujou_o_tsukurou/
https://www.mangago.zone/read-manga/solo_farming_in_the_tower/ (been on my want to read. Thanks to this post imma read it now lol)
Any gardening focused isekais? Lol im fucking OBSESSED with grow a garden rn, I need something to pass the time