Gardenias rhymes with:
banyas, begonias, california's, kenya's, pennsylvania's, tonya's, tonyes, vanya's, virginia's, australia's, azaleas, banyas, begonias, borjas, california's, julia's, kenya's, magnolias, pennsylvania's, thalia's, tonya's, tonyes, vanya's, virginia's
Gardenias sounds like:
garden's, gardening, gardens, gardini's, gerding, girding, gordon's, gradations, grading, graduating, graduations, grating, greatness, greeting, greetings, gretna's, gritting, grouting, guardian's, guardians, guarding, gyrating, gyrations, gyrodynes