Pumpkin

Pumpkin is the third and last defensive plant obtained in Plants vs. Zombies. Unlike the Wall-nut or Tall-nut, it does not occupy a garden space for itself, allowing other plants to be protected. The following plants cannot be protected with a Pumpkin: another Pumpkin, Sea-shroom, Tangle Kelp, Grave Buster, and Cob Cannon. Other plants can also be placed in an empty Pumpkin. Pumpkins have the same health as a Wall-nut. Like the Wall-nut and the Tall-nut, the player can plant a new Pumpkin over a damaged one without replanting it if he or she has purchased Wall-nut First Aid from Crazy Dave's Twiddydinkies.

Suburban Almanac Entry
Pumpkin

Pumpkins protect plants that are within their shells.

Toughness: high

Special: can be planted over another plant

Pumpkin hasn't heard from his cousin Renfield lately. Apparently Renfield's a big star, some kind of... what was it... sports hero? Peggle Master? Pumpkin doesn't really get it. He just does his job.

Cost: 125

Recharge: slow

Overview
The Pumpkin absorbs 72 bites and its appearance changes at 24 bites and 48 bites before being swallowed at 72 bites. It is planted around other plants and takes damage first. However, it cannot protect other plants from basketballs.

Strategies
Pumpkins are excellent on later levels, where the player needs to take out as much space as possible. Catapult Zombies and Bungee Zombies always target the plant inside the Pumpkin first, so they are useless as protection against them. They can be used to buy time so that your plants have more time to take out Digger Zombies. The best plant to put inside a Pumpkin (for defensive purposes) is the Tall-nut, so Pole Vaulting Zombies or Dolphin Rider Zombies cannot jump over them, and the zombies will have to eat the Pumpkin and the Tall-nut. Note, however, that it is not as efficient, sun-wise, as a Tall-nut alone; a Tall-nut and Pumpkin combo costs as much as two Tall-nuts, yet has only as much health as one-and-a-half. They are also useful for plants that the Imitater duplicates, because it protects them as they transform.

Don't put plants that are supposed to be eaten into a Pumpkin, such as Garlic or Hypno-shrooms. The zombies will have to eat the outside Pumpkin before eating the plant, so doing so will result in a waste of Sun. Pumpkins are usually good along with Potato Mines, as they give the Potato Mine time to arm, and once the zombies break through the Pumpkin, they will have come together onto one spot and will all be hit by the Potato Mine. The only problem with this is that, because of their larger horizontal hit-box, Football Zombies will trigger the Potato Mine while it is inside the Pumpkin, only killing some of the zombies as they will not all count as in range. As a result, it may make more sense to use a Wall-nut to protect the Potato Mine instead, as it is cheaper and will allow time for all of the zombies to get in range. Try to plant them on every plant except for Kernel-pults that you will upgrade into Cob Cannon, Spikeweed, Spikerock, Garlic, and Hypno-shroom.

When facing Gargantuars, put a Pumpkin around the plants in the third and second row so they are protected from the Imp.

Survival Mode
Almost all setups on Survival Mode use these. Because pumpkins can surround other plants, when player use pumpkins in lieu of Wall-nut or Tall-nut, it is more convenient to extend their defenses. For example, if you use Tall-nut on column 5 in all rows and the defense needs to be expanded to 6 columns, the sun that is used for planting these tall-nuts will be wasted, as they should be dug up, or there will be enough spaces for placing new plants. If you use pumpkins, just simply replace the plants without digging up the pumpkins. Pumpkins are usually used to protect plants at sensitive positions.

These are also very useful in Survival: Endless because they are excellent space savers, and can be used to protect your more valuable plants (Winter Melon, Gloom-shroom, Twin Sunflower) from zombies. If a zombie makes it through your defenses and you're vulnerable, Pumpkins might be the only thing saving you from the zombies successfully eating your brain.

Trivia

 * Pumpkin has a second degrade that can only be seen in the "reanim" folder, where the game stores its images.
 * Pumpkin's Suburban Almanac description references Renfield, a pumpkin in the 2007 game Peggle, another game by PopCap Games.
 * Pumpkin and Renfield are cousins, because they are pumpkins that appear in PopCap Games.
 * For some reason, the player can place Pumpkins on top of a Spikeweed or a Spikerock. If he or she places a Pumpkin on top of a Spikeweed when there's a zombie on it, the zombie will eat the Pumpkin and at the same time be attacked by the Spikeweed.
 * Pumpkin is one of the two plants without "real eyes", as its eyes are simply hollowed out of its shell. The other plant is the Chomper, which has no eyes. Pumpkin also does not have a real mouth, because like its eyes, it's simply hollowed out of its shell; this makes Pumpkin the only plant without eyes and a mouth.
 * A Puff-shroom is too small for a Pumpkin, but when it shoots a spore, the spore somehow passes through the Pumpkin's shell and still damages the zombies, which is unusual, though it could be going out through the Pumpkin's holes.
 * When a Pumpkin with a plant inside is squashed, it will have a flattened animation of the plant above a flattened Pumpkin instead of a flattened version of the plant in the Pumpkin.
 * A Starfruit lies on its back if it is less, but if a Pumpkin is added, it will stand up (as it would otherwise be completely concealed within the Pumpkin).
 * Bungee Zombies cannot take Pumpkins if they are surrounding another plant, except Lily Pad and Flower Pot. However, if a Bungee Zombie attempts to take a Cattail from a Pumpkin, it will cause the Cattail to downgrade to a Lily Pad. The same thing happens if you try to dig a Cattail from inside a Pumpkin. This is to avoid the Pumpkin from falling into the water.
 * This also makes Cattail the only plant able to downgrade.
 * When the player plants a Pumpkin around a plant and then the Pumpkin is eaten, the zombies will have to move forward a little to continue eating the plant that is inside the Pumpkin.
 * Pumpkin cannot be planted on Sea-shroom and Tangle Kelp because they are aquatic plants, but they can still be planted on Cattails, because it is the upgrade for the Lily Pad. Pumpkin cannot protect Cob Cannon and Grave Buster as well, because Cob Cannon is too big to fit and Grave Buster cannot be protected because it is on a grave, and graves cannot be planted on.
 * Pumpkin is the only defensive plant that does not lose its smile when eaten.
 * The Pumpkin is one of the four plants in Air Raid.
 * There is a way to dig up a Pumpkin without digging up the plant inside it. It involves using the shovel lower onto the square it is on.
 * If a Chomper is in a Pumpkin, when the Chomper sways to the right, its lower lip seems to go through the Pumpkin.
 * It is the only degrading plant that has an unused degrade look.
 * In DS version, it does not move; however, it moves in the Suburban Almanac.
 * In the iPad version, the holes on Pumpkin's top edge are missing. Also, it looks rounder.
 * The Pumpkin is based on a Jack o' Lantern in Halloween.
 * The Pumpkin is one of six plants whose purpose is to be chewed on. The other five are the Wall-nut, Tall-nut, Hypno-shroom, Chili Bean, Sun Bean, and Garlic.
 * The Pumpkin, Snapdragon and Cattail are the only plants with noses.
 * A Pumpkin prevents plants such as Gloom-shroom and Squash that are behind it from hitting zombies in front of it, as the Pumpkin has a slightly larger hitbox.
 * Putting Pumpkins on plants is almost always advantageous, except when Zombonis, Catapult Zombies, Gargantuars, or Giga-gargantuars appear; putting a Pumpkin on the front plant actually increases the chance of it being squashed. This is because Pumpkin has a larger hitbox.