This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
葧 combines the grass radical 艹 with 勃, which likely contributes sound. The exact historical development is uncertain.
The grass radical 艹 sits above 勃, a shape associated with sudden growth. Picture a plant sprouting vigorously, but its exact meaning remains unclear.
For ホツ, imagine a plant suddenly bursting forth with a 'hots!' sound: hots -> ホツ, as the grass 艹 springs up from 勃.