so been playing around with sugar cane and I found when u place a observer on the lowest sugar cane that the sugar cane seems to update the observer with out ever gowning the next cane ive linked 2 videos one of a farm that should work but doesn't and the other of 1 cane growing at 300 times normal tick speed not sure if this is a bug but it seems like it to me
MC-191356
sugar cane updates
Resolved
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0
The observer will trigger every time the growth stage updates, which is 15 times before it actually grows an extra one on top, so your farm design does not work like that.