An Etymological Dictionary of the German Language/Annotated/Beet
Beet, neuter, ‘bed (of a garden)’; earlier Modern High German Bett still common to Upper German; really identical with Bett, for the Middle High German has bęt, bętte, Old High German bętti, meaning also ‘(garden) bed.’ According to its form Beet (compare Biene) has arisen from the neuter singular badi, Bett from the cases in dj (genitive badjis, dative badja, neuter accusative plural badja, &c.). Compare Gothic neuter singular badi, neut, plural badja. English bed is also used in the same sense as Beet (so even in Anglo-Saxon riscbed), English bed of rushes, hotbed.