to store up / to grow (e.g. a beard) / to entertain (ideas)
蓄
=
艹
+
畜
:
Xu Xian (xu) is storing up (蓄) herds of cows (畜) in the space station's bathroom (Ø4). Each herd is living on a sheet of artificial lawn (艹) and when he gets a new herd, he just adds another layer on top.