Money

Money is used to buy items from Crazy Dave's Twiddydinkies. Before the shop is unlocked, it can be used to purchase seed slot upgrades directly from Crazy Dave, though the player can only have up to eight slots before the shop is unlocked after level 3-4. In most cases, money will drop under certain conditions, and the player must click on it, move the cursor over it, tap on it, or have a Gold Magnet collect it to obtain it, although it will sometimes be automatically added to the bank.

The player can't have more than $999,990; once that amount is reached, all money collected won't affect his or her total. Through cheating (see User File Format) it is possible to get up to $2,147,483,640, but this will be immediately reduced to $999,990 if the player purchases anything or picks up any coins. In certain GOTY versions and the iPad version, it is possible to earn more than $999,990.

Currency
There are three types of currency:
 * Silver Coins - worth $10
 * Gold Coins - worth $50
 * Diamond - worth $1,000

Coin Packs
On the iOS versions of the game, there are purchasable amounts of coins that add the desired amount to all Users on that device. They can only be purchased once, but they can be purchased again on another Apple device that is hooked up to the same iTunes account. The price in real-world money goes up depending on the in-game amount. If the player has money in his or her iTunes account, it will withdraw money from that. The options for buying are:

Earning money
Money can be earned in several ways:

In the game, if you don't have enough money to get something, it says to get more by killing zombies.
 * Killing Zombies (sometimes coins, diamonds, chocolate, or Zen Garden plants may drop), and killing a Zombie Yeti will drop four diamonds (five on the first sighting).
 * Unused Lawn Mowers, Roof Cleaners, and Pool Cleaners (they turn into gold coins after each level and are automatically collected).
 * Marigolds (they drop silver and gold coins).
 * Completing Levels (when Mini-games, Puzzle Mode levels, and Survival Mode levels are completed, a money bag or trophy is dropped; clicking on it will cause coins or diamonds to be automatically collected).
 * Eating Brains in I, Zombie (coins, diamonds, presents, or chocolate may drop).
 * Every ten levels in Vasebreaker Endless (the last vase or killed Zombie will drop a money bag).
 * Completing Adventure Mode levels after beating them for the first time (the last zombie will drop a money bag with five gold coins in it).
 * From Zen Garden Plants (Zen Garden plants drop money after being watered or fertilized, as well as after the Phonograph or Bug Spray is used on them. After the Phonograph or Bug Spray has been used, they also drop occasional coins in a manner similar to Marigolds).
 * Destroying a Grave with a Grave Buster (coins, diamonds, presents, or chocolate may drop).
 * Selling Zen Garden Plants (directly adds a certain amount of money to the bank balance; this amount depends on the type of plant and its maturity).
 * Slot Machine (sometimes gives diamonds when spun).
 * Completing Adventure Mode will give the player three diamonds.
 * Getting the Gold Sunflower Trophy (five Diamonds).

Trivia

 * In the United Kingdom, money bags, coins and the dollar hedge on the leader boards (Xbox Live Arcade version only) will show £ signs but the currency will still be United States dollars.
 * The Silver Coin is common, the Gold Coin is uncommon, and the Diamond is rare.
 * In the iPhone, iPod Touch, and iPad versions, the coins have a sun emblem instead of a dollar sign emblem.
 * Diamonds are an indirect reference to the Bejeweled series of games, also made by PopCap Games.
 * They could also be a reference to Insaniquarium, another game by PopCap Games.