Plants are still reverting. :(

best thing to do is to hire a gardner. Get the reward trait for free services if you are concerned about costs. I always cheat and give my sims 25,000 reward points so I can purchase whatever reward traits I want. Also install sprinklers and upgrade them. With the gardner and sprinklers you don't have to water the plants yourself nor weed them. The plants only revert when you water them not when a NPC waters them. then you can harvest and evolve plants with no issues.