The Gardening Gnome is an NPC that Sims can create by casting the Enchant spell on a gnome made with the Woodworking Table. Gardening gnomes will water plants and tend to any gardens a Sim has - until the spell wears off or a magical Sim solidifies the gnome. If a gnome is enchanted on the second story of a lot, the he will jump down the stairs in a rabbit like motion.
If there is a nectar press on the lot, gnomes will occasionally swim around in it and then comically stagger around drunk for a few minutes.
Also, if the charm Perfect Garden is cast while a gnome, enchanted or otherwise, is on the lot, all gnomes on the lot will become animated, and will rampage through the lot, destroying the garden. This is not the only time Gardening gnomes can act violently. If there is a Gardening gnome on the lot, and the NPC Gardener arrives on the lot, the Gardening gnome will attack the Sims by stomping on their feet.