This week's PlayStation Plus update will add another game to the Vita's Instant Game Collection. Sony has announced that the PopCap hit lawn-defense game Plants vs. Zombies will be added to the Plus line-up tomorrow, along with a few discounts and a Vita anniversary sale.

The PlayStation Blog announced that PvZ will shamble up to Plus this week. Retro/Grade is also getting a heavy discount, down from $9.99 in the Store to $2.44 for Plus subscribers.

The update will also bring about the Vita Anniversary sale, bringing steep discounts to 13 games in the Vita library. As previously reported, tomorrow's store update will pack discounts on the winners of the Gamers Choice Awards as well. The sale will be store-wide, but Plus members get deeper price cuts, so you'll have no excuse left not to buy Journey.