Anyways, Pixies are as random as the pests themselves. Besides keeping plants from wilting, I don't believe there is a way to make them appear.
"Your plant may also get pests, both good and bad. Rid your plant of these pests by casting the appropriate spell for the level of the pest. Good pests are rare, and you cannot (nor do you want to) remove them from your plants."-- From the Wizard101 Player Guide
Garden pixies are pests, but they are the nicest pests you'll find! You can't get rid of them, but it's better if you don't anyway because they help a plant grow better, like a garden gnome helps a Stinkweed grow better. But the catch is that they randomly appear, and they cannot be cast on a plant like, for example, Gusty Winds can (Gusty Winds kills rank 1 and 2 pests). If they do appear, consider yourself lucky!
Jordan FireBringer, lvl 36 Fire Elijah DeathBringer, lvl 7 Death Patrick Star, lvl 1 Storm