Garlic

Garlic will cause any zombie that bites it to move up or down to the next lane (they can't stand the taste).

The plant Allium sativum, commonly known as Garlic, is a pungent member of the onion family, often used for cooking, and to keep vampires at bay.

Overview
Can take 21 bites. Appearance changes at 7 bites and 14 bites before being swallowed at 21 bites.

Usage
Place Garlic in the front of lanes to divert the zombies into other lanes, preferably those with greater defenses or attacks. Garlics only affect zombies that bite them, so they will not stop Zombonis, Catapult Zombies, or Gargantuars, as they don't actually eat the garlic, so plan accordingly. Also, Garlics will stop neither Pogo Zombies nor Pole Vaulting Zombies if they still have their equipment, since they will just jump/pole vault over it. Balloon Zombies with balloons will float over any Garlic beneath them without effect. Garlics may not stop Dr. Zomboss either; they player never gets a chance to do that. Garlic is useful in some levels.

Strategy
Garlic is a useful plant on almost any level, because with careful use, it can funnel zombies down lanes with greater defenses. It is often used in combination with the Gloom-shroom diverting zombies to the sides of the mushrooms, so that they will be damaged by the mushroom and not be able to attack it. It can also be used so that you don't have to defend as many rows, leaving more room for Sunflowers, Marigolds, etc. After taking a bite of the garlic, zombies will not only shift over by one lane, but also advance slightly into the new column. Zombies that have bitten the garlic will also pause for a moment before changing rows. Also, add few (if any) defenses into lanes with Garlic that do not hit other rows, for they will not hit the zombies that have bitten the Garlic; however, again, with something like a Gloom-shroom (or perhaps a Cob Cannon), placing them behind Garlic is a good idea. Threepeaters are better used behind Wall-nuts or Tall-nuts to maximize the effect. Be aware that if you are using adjacent Garlic in different lanes, zombies won't be held up indefinitely; they will still move through to the other side after four or five bites. Also, use two Garlics in the same lane when dealing with Pole Vaulting Zombies, as they will vault the first one and then encounter the second.

In the Mini-game Seeing Stars, it is helpful to use a Garlic in the middle lane at the beginning (the one with most Starfruit places and therefore most vulnerable) so they will go into lanes where you are using defensive plants.

Keep an eye on the health of your Garlic. You can't replace damaged Garlic without digging it up, so try to be prepared for when it finally gets eaten, so you can replace it immediately. Garlics should be replaced shortly after their eyes start to water, which means they are almost completely eaten.

In the Last Stand Mini-game, Garlic is often used in conjunction with Gloom-shrooms, Pumpkins, and Marigolds, to create an effective gold-farming strategy.

Trivia

 * If a zombie bites a piece of Garlic when the "future" code is entered, it will not pause and make a disgusted face or a "bleh" noise, but will instead move to a different lane without making a sound.
 * Another odd glitch may occur if the "future" code is entered while a normal zombie makes a disgusted face; the zombie may lose its mouth which is weird.
 * Like the Tall-nut, the Garlic will shed a single tear before being eaten completely.
 * The Garlic is one of four plants that will slowly degrade as they are eaten. The others are the Wall-nut, Pumpkin, and Tall-nut.
 * This is the only defensive plant which can't be aided by Wall-nut First Aid, most likely because you did not have the Garlic seed packet when you are given the opportunity to purchase Wall Nut First Aid.
 * On the iPad version of the game, if a Zombie bites a garlic, the zombie's head will move up, except for the headwear zombies. (i.e. Buckets, Cones.)
 * Although it has can withstand more bites from Zombies than most plants, the Garlic only takes six basketballs thrown by Catapult Zombie before dying, the same as any other plant.
 * If a Hypnotized Zombie tries to eat a Zombie that's not hypnotized, and there is a Garlic in the way, the Zombie and/or the Hypnotized one will be disgusted and move to the other lane.
 * Garlic is the only plant that can be eaten but could be passed by zombies. It is also the only defensive plant that Ladder Zombies do not place their ladder on.