Snow Pea

The Snow Pea is the second offensive plant that you get in the game which is not Instant. It is also one of the three plants that can slow down zombies by freezing them. It does the same amount of damage as the Peashooter, but with its slowing effect, makes it a valuable asset in your arsenal of plants.

Usage
Plant Snow Peas anywhere you would plant Peashooters. They have the same damage and rate of fire as a Peashooter, but since they slow zombies down, they can actually do more damage to a zombie before it can reach the Snow Pea. Slowed zombies move and attack about half as fast as regular zombies of their type. It can also slow down fast zombies but cannot slow down the Zomboni. The slowing effect lasts even after the Snow Pea has been eaten.

Suburban Almanac Entry
Snow Pea

Snow Peas shoot frozen peas that damage and slow the enemy.

Damage: normal, slows zombies

Folks often tell Snow Pea how "cool" he is, or exhort him to "chill out." They tell him to "stay frosty." Snow Pea just rolls his eyes. He's heard 'em all.

Cost: 175

Recharge: fast

Standard levels
A single column of Snow Peas will slow the the incoming horde. Multiple Snow Peas in a single lane don't perform much better, not providing additional slowing effects, so unless you're getting them for free, there's probably no need to plant more than one per lane as they are useless and cost Sun. Of course, having multiple is helpful when zombies eat one, as they will remain slowed. On the roof levels, Snow Peas cannot shoot over the roof's edge unless they are in the first sloped column, so they are not too helpful.

Snow Peas work well in conjunction with Wall-nuts/Tall-nuts and Spikeweed/Spikerock. Slowing the zombies down allows more time for the spikes to do damage to the zombies.

Note that if a frozen pea passes through the flame of a Torchwood, it will thaw into a regular pea. Furthermore a slowed zombie hit with a flaming pea will thaw, so it is generally unwise to use Snow Peas in the same lanes as Torchwoods. But if two Torchwoods are placed in the same row where a Snow Pea is planted, the frozen pea will turn into a flaming pea. Also, Screen Door Zombies are immune to the Snow Pea's slowing effect as long as they still have their screen door; the same applies with Ladder Zombies and their ladders, as well as Newspaper Zombies and their newspapers.

If you still wish to use a Snow Pea with a Torchwood, you could place the snowpea in front of the torchwood. However, the normal flaming peas will still unthaw its target, making it relatively useless in this situation. Also, once Winter Melons become available, it may be a good idea to replace Snow Peas in favor of the damage and splash slowing effect.

Slot Machine Mini-game
You can't really control when you get Snow Peas, but try to spread them out, one per lane, until you have at least one in each lane. It depends on your luck when you get them or not.

Trivia

 * Its name is a reference to the snow pea, a pea that grows at the end of winter.
 * This is one of the three Plants that have ice crystals and freeze Zombies that approach Your House, the other two being the Ice-shroom and the Winter Melon.
 * Snow Peas are effectively the same as a Repeater, because they do the same amount of damage per step the zombie takes. However, the Snow Pea cannot be stacked on a single lane, as the freezing effects only the first zombie in the row.
 * If there is a Peashooter (or a Repeater, Threepeater, etc.) shooting in the same row with a Torchwood before the Snow Pea (the Peashooter using the Torchwood and the Snow Pea put in front of the Torchwood), the fireball (this refers to the pea with a Torchwood, not the Fireball that Dr. Zomboss unleashes) will cancel the effect of the Snow Pea or vice-versa, so it is not advisable to put a Peashooter with a Torchwood on the same lane as the Snow Pea. It is also not advisable to put a Snow Pea before a Torchwood, as it will turn the Snow Pea into a normal pea.
 * When a Snow Pea shoots. A small 'Plink' sound can be heard.
 * In the online version, when the pea that the snow pea hits a zombie, a shattering sound can be heard, as if the ice had broken.