window box
US /ˈwɪn.doʊ ˌbɑːks/
UK /ˈwɪn.doʊ ˌbɑːks/

1.
jardinera, macetero de ventana
a long, narrow container for growing plants, typically placed on a windowsill or attached to the outside of a window
:
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She filled the window box with colorful petunias.
Ella llenó la jardinera con petunias coloridas.
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The old building had charming window boxes overflowing with geraniums.
El edificio antiguo tenía encantadoras jardineras rebosantes de geranios.