Smarter than the average zombie, these Shield Zombies have decided to improvise special protective equipment from their surroundings. While a newspaper or a screen door aren’t exactly the best shields in the world, they can block critical hits to the zombie’s head. You either must find an opening on the shield, or flank the zombie to score those critical hits. You can also destroy the shield itself.
Newspaper Zombie

The fastest way to eliminate zombies is to aim for the head. These grumps are protecting their heads with a newspaper. Destroying the newspaper will take away this layer of protection, as well as the only way this zombie can keep up with current events. Without the news, this zombie grows angry, attacking nearby plants and charging faster at the Garden. Ideally, you should flank the Newspaper Zombie to score headshots.
Screen Door Zombie

These zombies have acquired a screen door for protection. The quick answer to a Screen Door Zombie is the same as it is with a Newspaper Zombie: flank ’em, and vanquish ’em.