PlantUp Upgrades Guide: Buy for the Bottleneck You Observed
Use the official upgrade concept without inventing a ranked upgrade list.
The official PlantUp description mentions clever upgrades. It does not publish their names, prices, or effects, so there is no honest universal ranking to list here.
Make an upgrade decision
First name the problem you actually saw: growing work waits, processing work waits, or customers wait. Then inspect the current upgrade text and ask whether it addresses that exact problem. Test one change at a time and compare the next few shop cycles.
Avoid false certainty
An upgrade that helps one build, stage, or version may not help another. Keep a dated note containing the in-game wording and the result you observed. That is stronger evidence than copying an unverified tier list.