sprout
蘖 centers on a new shoot or sprout, especially one growing from a tree stump or root.
蘖 combines 木 (tree) with 薛, which likely contributes the sound and relates to cutting or sprouting. The character originally referred to shoots growing from a cut tree stump.
The top 薛 looks like a tangled thicket, and 木 is a tree. Picture a tree stump with fresh green sprouts pushing up through the thicket.
For ゲツ, imagine a sprout getting its first leaf: the sprout 'gets' a leaf, and 'gets' sounds like ゲツ.