Ice-shroom


 * For the version in Plants vs. Zombies: Garden Warfare, see Ice-shroom (PvZ: GW). For the plant in the Chinese version of Plants vs. Zombies 2 with a similar name, see Freeze Mushroom.

Ice-shroom is a mushroom appearing in Plants vs. Zombies. When activated either through normal planting in Night and Fog levels, or through waking up via Coffee Bean in levels with daylight, Ice-shroom will freeze all enemies currently on the field, dealing 1 normal damage shot worth of damage and stunning them for 3.25 seconds. Afterwards, the affected targets will continue to be chilled for another 16 seconds, during which their movement and attack speed are halved.

Airborne enemies will only suffer from the freezing effect, while Zomboni, Zombie Bobsled Team and underground Digger Zombie are immune to Ice-shroom altogether. Attacking with fire-based plants will also immediately remove both the stunning and freezing effect.

In the iOS versions of the game, freezing 20 full-size enemies with a single Ice-shroom will give the player the 20 Below Zero achievement.

Suburban Almanac entry
Ice-shroom

Ice-shrooms temporarily immobilize all zombies on the screen.

Damage: very light, immobilizes zombies

Range: all zombies on the screen

Usage: single use, instant

Sleeps during the day

Ice-shroom frowns, not because he's unhappy or because he disapproves, but because of a childhood injury that left his facial nerves paralyzed.

Cost: 75

Recharge: very slow

Strategies
Ice-shroom is a useful plant that can help the user in delaying the horde and maximizing the plants' efficiency. As he can affect every single enemy on the screen, Ice-shroom will prove to be highly useful in normal levels, as other slowing options are either expensive or limited in scale. Ice-shroom's value however suffers greatly in Survival: Endless, as the player is likely going to have enough Winter Melons to suppress the horde, and the stunning duration of only 3.25 seconds is too trivial to have a great impact on the battle.

Unlike most other mushrooms, the nocturnal plant mechanic does not necessarily affect Ice-shroom negatively, as he will not activate immediately when planted in daylight levels. This allows the player to "stockpile" Ice-shrooms by planting them on safe space and activating them when needed. Pumpkins can also be used to guard sleeping Ice-shrooms, giving the player more liberty in storaging them for further use.

Level 5-10
Ice-shroom is provided in this level as the only method to negate Dr. Zomboss's fireball attack. Therefore, the player should not try to deplete their stock too quickly, and instead only use Ice-shroom when either a fireball or dangerous enemies are present. Stunning Dr. Zomboss when he lowers his robot can also speed up the level by giving the plants more time to damage him. However, unless there is an iceball present, avoid using Jalapeno when he is frozen, as the fire will take away both the chilling and freezing effect.

Invisi-ghoul
As invisible zombies will still have ice formed on their feet when frozen, Ice-shroom can be used to scan the lawn for potential threats. This will not work on pool lanes however.

Survival: Endless
In Survival: Endless, Ice-shroom will see his value inversely proportional to the amount of Cob Cannons utilized by the player, as the few seconds earned with each Ice-shroom will matter more when less firepower is present to actually fight the horde. Stockpiling Ice-shrooms remains a powerful strategy, and there are three ways the player could do this:
 * Placing Ice-shroom on the pool row is the safest option, since there are much less pressure from the zombies in these lanes. However, the pool is also the best place for installing Cob Cannon and Twin Sunflower for the same reason, therefore this option will force the player to sacrifice great amounts of firepower.
 * Placing Ice-shroom on the back columns in normal lanes will expose him to Imps and Digger Zombies, forcing the player to divert further attention to Pumpkin maintenance. This is usually the preferred option however, since it does not require much firepower sacrifice.
 * Placing Ice-shroom at the frontline is the most dangerous option, as this will put Ice-shroom in the path of various threats such as Zombonis, Football Zombies and Gargantuars. This is usually a last ditch option, but it still has its merits, namely not allowing Imps to attack Ice-shroom and not requiring Pumpkin if the crowd is well controlled.

Trivia

 * When an Ice-shroom explodes, snowflakes can be seen.
 * He is the only explosive plant in Plants vs. Zombies that is not an instant kill.
 * This and Blover are the only instant-use plants that affect the entire screen.
 * This is discounting Thyme Warp, as he only appears in Plants vs. Zombies 2.
 * When used on a Pool or Fog level, the pool's animation stops until the zombies are unfrozen.
 * Even though his Suburban Almanac entry says that the damage is very light, it is actually the same as damage from one pea, which is stated as normal in Almanac.