Gardener
The gardener is an NPC that can be hired in The Sims and The Sims 2 to take care of all the out of the way plants. They can be pricey, but they tend to do all the work really fast.
In The Sims, the gardener will come every three days, and charges 10 simoleons per hour. She will leave if she encounters a plant she can't get to, or if her route is blocked for too long.