Welcome to the BRD-MC Cacti.

It's fairly loose to call this a redstone device but as it uses hoppers from the redstone page to feed the storage chests I'll take it :D

Okay Okay... this one is indeed more simple than the Kelper but like the Kelper it stacks for higher output. This cactus farm houses 36 per level and uses no redstone other than hoppers. The functionality is as basic as it gets.
When the cactus grow to the next height level they hit the metal bars causing them to break. The broken cactus are taken by water flow to storage of 80 dbl chests total. When these are full the drops will bypass the chests and terminate to lava.

The Cacti can be used as just the single level with storage known as the Main or the Stack sections can be added on top of one another as desired.

Schem Main is 16x16x13 tall. You are facing South up against the front left corner (A side with chests) at ground level.

Schem Stack is 16x16x6 tall

:)