Ice-shroom

Ice-shroom freezes all the zombies on the screen for a few seconds. It is single use, to activate it just drop it in any empty spot on the screen. After a second, the Ice-shroom will freeze every zombie on the screen and do a slight amount of damage to each one. Zombies will have ice at their feet like ice sculptures. Zombies will unfreeze after a couple of seconds, but then will be slowed for a few more seconds, usually long enough to be killed.

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

Standard Levels
Plant the Ice-shroom when tough zombies are trying to eat your other plants. Against Dr. Zomboss, the Ice-shroom can be used to destroy fireballs, and also to freeze him so he can be damaged for more seconds at a time.

Note: Try to not spam them in Dr. Zomboss, when he puts his head down use as much as you can, until you feel that he's going to go up.

In Survival: Endless it may be a good idea to plant an Ice-shroom before it is needed so it can be saved for later, but this may not work if there are hard-to-stop zombies that could get to it and eat it. In iPhone/iPod Touch/iPad version of the game, immobilize 20 full-sized zombies with a single Ice-shroom will earn you the 20 Below Zero achievement. The Ice-shroom can be planted anywhere and still freeze all on-screen zombies.

Whack-a-Zombie Mini-game
Use the Ice-shroom when you need a little extra time to whack a large wave of zombies. If you have enough Sun, you can take that time to drop a Grave Buster at the same time. Use this only during the later part of this level as there will be more Zombies.

Trivia

 * The Ice-shroom is one of the only three plants that have ice crystals on their body. The other two are Snow Pea and the Winter Melon.
 * The Ice-shroom is the only plant that fully immobilizes zombies by freezing, the only other plant which immobilizes zombies is the Kernel-pult but he uses butter.
 * Although the Almanac says Ice-shroom damage is very light, its damage is actually equal to a pea. Therefore, 10 Ice-shrooms would kill a normal Zombie, 28 for a Conehead Zombie, etc.
 * The damage rating for a pea is "normal," as opposed to the Ice-shroom's "very light."
 * If an Ice-shroom is sleeping, its eyes won't be seen. The same happens to the Scaredy-shroom.
 * The Ice-shroom is the only plant that has a purely a light blue hue. Both the Snow Pea and Winter Melon have green and light blue colors.
 * The Ice-shroom is one of the seven plants that frown, the others being the Gloom-shroom, the Fume-shroom, the Tall-nut, the Torchwood, the Doom-shroom, and Garlic when at full health (Garlic frowns only on the DS version).
 * The Ice-shroom is still counted as an explosive plant as you can see a blue flash with snowflakes when it freezes all the zombies.Snowflakes.jpg
 * The Ice-shroom is the only plant that can attack every zombie in the screen simultaneously.
 * The Ice-shroom & Blover have the largest area of effect among all Area of Effect Plants, being the only two with a full-lawn coverage.
 * Coincidentally, Ice-shroom and Blover are the only plant with a childhood history in the Suburban Almanac, Ice-shroom when he had a childhood injury, and Blover when she was five years old.Ice-shroom123.jpg
 * In the Plants vs. Zombies website, the Ice-shroom looks mad.
 * Ice-shroom is one of the twelve plants that appear in the seed selection screen after you get the Grave Buster on the online version, the others are: Doom-shroom, Lily Pad, Potato Mine, Threepeater, Tangle Kelp, Jalapeno, Spikeweed, Torchwood, Tall-nut, Cactus and Blover.
 * The snowflakes from the Ice-shroom and the the Imitater Ice-shroom are white.
 * The Ice-shroom and Potato Mine are the only exploding plants that do not expand when exploding.
 * Ice-shroom is the only plant with the prefix name of Ice-.
 * The Ice-shroom, Snow Pea, and the Winter Melon are the only plants whose effects cause a killed zombie to fall over at a slower rate.
 * It is the only plant that can freeze all zombies on screen.
 * In Survival Endless mode, sleeping Ice Shrooms can be stored in back spaces and detonated with a Coffee Bean when a temporary delay is needed.
 * Actually, Ice-shroom can even freeze some zombies that aren't on the screen yet, making him the only plant that can attack zombies not on the screen.
 * Ice-shroom does not activate instantly. He waits for about a second.
 * When activated, the Ice-shroom will destroy all ladders on the screen.
 * The Ice-shroom, Jalapeno and Cob Cannon are the only explosive plants that don't create a word while detonating.