花壇
かだん · kadan · JLPT N1 · noun
flowerbed
🌷 花 flower + 壇 raised platform: a flower bed is a raised platform for flowers
The kanji 壇 means a raised platform or mound, as in 土壇 (earth mound). 花壇 is a patch of ground raised up to hold flowers.
花 — grass radical 艹 + 化 (change/phonetic)
花 is a semantic-phonetic compound. The top 艹 (grass) signals the plant meaning, while 化 ('change, transform') gives the sound and hints at how buds change into blossoms. It originally meant 'flower' or 'blossom' and later extended to 'flowery, patterned, to spend.'