I used to be the tea farmer for a 30 man clan on a Vanilla Monthly server. I had 60 planters in my farm and within a week and a half of the wipe, I had already farmed enough of everything to last the full month if the team kept going the full month.
The amount of planters some people have on this server is just wild and unnecessary.
I think a limit is proper to help the performance of the server. 50 would be way more than enough planters and would be a more than reasonable limit in my opinion.