The key to helping with Plants vs. Zombies is to understand that it's not a straight-forward go here, go there, like with Hidden Object-games or Adventure-games. Instead, I'll give you some helpful strategy basics, the pros and cons of of your plants, a strategy against the different zombies, and tips on the extra puzzles and mini-games.
The times in this walkthrough are given in patches, which stand for the amount of patches an average zombie walks; this comes down to about 5 seconds per patch.
Besides Gamezebo wisdom, at the end of the walkthrough, you will find tips and tricks from the Tree of Wisdom.
Easter Eggs – funny extras
Type in the following codes during gameplay to activate them. Type them in again, to de-activate them. For some of the Easter eggs, your tree of wisdom needs to be a certain height, but often (not always, sorry if you are unlucky), you will be able to turn the Easter eggs on at any point.
"future" - the zombies wear retro sunglasses
"mustache" - the zombies get a mustache
"trickedout" - a visual upgrade of the lawnmowers
"sukhbir" - toggles the zombie's call for brains sound
"pinata" - a shower of candy when a zombie dies (tree of wisdom at 500 feet)
"daisies" - flowers sprout from fallen zombies (tree of wisdom at 100 feet)
"dance" - makes the zombies dance (tree of wisdom at 1,000 feet)
Basic strategy – sun production
From the go, you will want to start planting as many Sunflowers (or Sun-shrooms at night) as you can. In general, your aim should be to plant around 10 to 12 sunflowers total.
Situation: A zombie approaches, and I must choose to plant an attack plant, or another sunflower.
Your choice depends on how far away the zombie is, and your current amount of suns. The image below shows you an example.
In the pool-level, you will be rewarded with a Twin Sunflower, which will produce two suns at once.
Do not plant this untill you have planted all the sunflowers you are going to, since the extra costs can be better used.
While you can use sunflowers at night, their extra costs don't weigh up to the initial extra sun production, so it's best to use just sunflowers during the day, and just sun-shrooms during the night.
Basic strategy – deciding upon your arsenal
At the start of each new level, you can choose which plants you want to choose.
On the right side of the screen, you will see which zombies you will encounter in this level.
You start with 5 plant-slots, but as your adventure progresses, Crazy Dave will offer you extra slots.
You will want to get up to 8 slots as soon as possible, but the 9th can waith (also because it's just very expensive). If you're running short on money for the 8th slot, you likely will, you can try and play mini-games to gather some extra money.
When deciding your arsenal, you first need to select the basics. You need a sun-producing plant, a cheap attack plant (you need them for the start of the level), and I would advice to choose at least one life-saver, such as a Cherry Bomb or Jalapeno, that can provide a last defense.
If you are going to get a Digger zombie, don't forget to get a split pea or a magnet, while the Balloon zombie will require either a Cactus or a Blover. The rest of the slots, you can fill with your favourite plants, depending if you like to play it agressive or defensive. Personally, I like combining peashooters with torchwood, but each player may have their own preference.
Basic strategy – timing your gardening
It may come as a shock, but zombies do not play nice. When you think you're almost save, and have a decent defense on 3 of your 5 lanes, suddenly two zombies appear on the other two. How are you going to stop them both!?
Timing is essential in this game. The above situation might make you feel helpless, but if one zombie is much slower then the other, that gives you the chance to tackle them both. That's why I've made a little chart below, with the average time (in distance covered by a zombie) it takes the most common plants to kill a normal zombie, and how long it takes to kill a Conehead zombie.
Peashooter 2.5 patches
Repeater 1.25 patches
Threepeater 2 patches
Spikeweed 2 patches 4 patches
2. 5 patches forward
1.25 patches backward
3 patches backward
Cabbage-pult 2 patches
Shooting a pea through Torchwood will kill zombies twice as fast as normal.
A Potato Mine takes 3 patches to arm itself, but will be eaten by zombies if not armed. It recharges in 30 seconds (6 patches).
The Wall-nut will stall zombies for 35 seconds (7 patches), and recharges in 25 seconds (5 patches).
The Tall-nut will stall zombies for 70 seconds (14 patches), and recharges in 25 seconds (5 patches).
It takes a Chomper 40 seconds (8 patches) to digest a zombie, during which time it is vulnerable to attacks.
It takes a Grave buster 5 seconds (1 patch) to clear a grave, and it recharges in 7.5 seconds (1.5 patch).
It takes a Squash 30 seconds (6 patches) to recharge.
It takes a Tangle kelp 30 seconds (6 patches) to recharge.
It takes a Jalapeno 50 seconds (10 patches) to recharge.
The Kernel-pult randomly fires either kernels, which take out a normal zombie in 5 patches (12 for coneheads), or butter, which will immobilize the zombie and takes out a normal zombie in 3 hits (7 hits for a conehead).
The Sunflower and Sun-shroom produce their first sun in 7 seconds (1.5 patch), but then take 20 seconds (4 patches) for every next sun. Recharging takes 25 seconds (5 patches).
The game has a very nifty Suburban Almanac, which can be found in the main menu, that shows you a description of all the plants you have unlocked. In this section, I will give some additional hints on how to maximize the use of some of the plants.
Chompers devour a zombie in one bite, but then take a long time to digest them. This makes them less effective in levels with many zombies. An effective way to work with them still, is to plant two chompers behind eachother, so when the first one is still digesting, the second one can eat the next zombie. You can also plant a wall-nut or tall-nut in front of them, who can protect the chomper for nearly the entire time it's digesting.
Puff-shrooms are only used at night (waking them up with a coffee bean costs 75 sun, you can get better for that money), but they are free! It takes them 1.5 patch (7.5 seconds) to recharge. Their range is 3 patches, which is just enough to kill a single zombie before it starts chomping its head off. Be carefull not to place them closer to a zombie if you can help it.
Fume-shrooms, another nocturnal plant, are your best attack against those Screen Door zombies. Luckily they have an added advantage of hurting multiple zombies at the same time. The Gloom-shroom you can put on top of it, limits its forward attack to 2 patches, but offer an extra 2 patch range to all other sides as well. However, planting them on the outside of the lawn, is quite a waste of money.
Grave buster is a bigger help then you would firstly expect. During the final wave, most zombies come from the graves, yet if you clear the graves with this fearsome looking plant, the final waves will actually be a piece of cake. Take your time clearing the graves, you have the entire level to do so, so just send them out when you have suns left to spare.
Hypno-shrooms take over a zombie when eaten and have them turn around and fight the other zombies, so naturally they are best used on the bigger zombies, like Football zombies.
Scaredy-shroom is a cheap plant which works well in the back of your defensive lines, but cower and hide as soon as a zombie comes within 1 patch of them, leaving them wide open to a chomp-fest.
Doom-shrooms are like the attomic bombs of the plant world. When they explode, they take out every zombie on 3 patches in each direction; a 25-patch area. They do leave a crater that can not be used for planting anymore though, but in time the patch will heal.
Squashes are a good final defense, for whatever you really don't want to lose. They stomp every zombie on their patch, and the first patch to their left and their right.
Threepeaters can be quite usefull in protecting a big area, and also do a little more damage with each single pea. Since they cover three lanes at ones, it'd be a waste to plant them on the sides.
Spikeweed may not seem very useful on it's own, but in combination with other spikeweed, or other plants, it will get the zombie down eventually. One walk across a spikeweed takes about half of a normal zombie's health.
Torchwood doubles the strength of any pea shooten through it. They also drive away fog in 3 patches in every direction.
Sea-shrooms are the aquatic equivalent of the puff-shroom.
Planterns light up an area covered in fog. As long as they are not eaten by zombies, they will clear 3 lanes of fog.
Split peas are especially effective when dealing with Digging zombies, who try to attack from behind.
Pumpkins are placed over other plants, and offer them an extra layer of protection against zombie gnawing.
Kernel-pults can be either very effective, or very useless, because of their random attacks. If you're in bad luck and they only shoot kernels, you won't live very long. They work best in combination with another pult, that backs them up when they're shooting the weak ammo.
Garlic can be extremely usefull, essentially completely protecting parts of the level. If you put one on the first, third and fifth lane, you basically have only got 2 lanes left to protect. You can put them next to eachother, but as the zombies change lanes, they also go forward half a patch, so they will eventually get through.
Marigolds give you coins throughout the entire level, but certainly in the harder levels, are not really worth the risk of planting them instead of an attack plant.
Cattails are planted on lily pads, but can attack any lane, giving them a very wide range of attack. They also take down Balloon zombies.
Cobcannons are the most expensive plants available, but have a huge impact of 3 patches in each direction from the point of impact. Plant two kernel-pults behind eachother to be able to plant one of these big guys. Be careful for the time they take recharging between shots though: a hefty 25 seconds (5 patches).
Imitator makes it possible to fill 2 slots with the same plant, meaning you won't have to wait as long for some plants to recharge.
The game has a very nifty Suburban Almanac, which can be found in the main menu, that shows you a description of all the zombies you have encountered. In this section, I will give some additional hints on how to best take on some of those thougher zombies.
Pole Vaulting zombie jumps over the first plant he encounters, so if you encounter him in a level, make sure you have a back-up.
Buckethead zombies are tough critters, that take a lot of damage before going back to being undead; up to 5 times as much. Consider a squash or other one-hit wonders if you don't have the artillery to bring them down. A magnet-shroom will make your life with these zombies much easier though.
Screen Door zombies are very though with their screen door shield, but if you use a magnet-shroom to take the door, or a fume-shroom to shoot through the door, they will be down soon enough. It is adviced to plant a fume-shroom as soon as you see these guys enter the screen though.
Football zombies are though like the buckethead zombies, but are also fast! Same strategy applies, but you'll have to act faster.
Dancing zombie is a nightmare, not just because he fails to see how his carreer is over, being dead and all. As soon as you see him, kill him with anything immediate, like a squash or cherry bomb, before he summons a bunch of Backup Dancers.
Snorkel zombies swim underwater, but will have to come up to get past a barrier like a lily pad. Unless you have a tangle kelp to take these zombies out, their consuming your plants is your chance to take them down.
Zomboni is a zombie on a zamboni, and very though because of that. Even worse, he crushes your plants and leaves a trail of ice behind him, which opens the way to the Zombie Bob Sled Team and the Zombie Yeti. Take him out as fast as possible, with a Jalapeno or Squash. A Jalapeno will also melt the ice trail he left.
Dolphin Rider zombies are your worst nightmare in the pool, as they are very fast and jump over your first plant. A trick to still catch him in your plant's line of fire, is to plant a lily pad at the beginning of the pool, so he jumps over the lily pad and is then slow as a normal zombie.
Jack-in-the-box zombies are fast, but other then that, pose no big threat.
Balloon zombies think they're smart by floating over your attack plants, but are easily taken down by a cactus or a blover.
Digger zombies are tricky zombies that dig through your garden, come out at the other end and eat their ways through your plants from the back. Use split-peas to have a guard against them, or a magnet-shroom to stop them in their underground tracks.
Pogo zombies jump over nearly every plant you put in front of him, but is stopped short by a magnet-shroom.
Bungee zombies are death from above. Just before they drop down, you will see a bulls-eye appear on the ground, and before you know it, they've come and gone with one of your plants. The umbrella leaf is your only defense against them, though you could catch them with a Jalapeno, but in general, it's best to just take your loss.
Gargantuar is, well, gargantuan, and so is his toughness. The chances of killing him with normal attacks are so slim, you're best of with a squash, cherry bomb or jalapeno. Preferably before he throws his Imp friend behind your lines.
Dr. Zomboss is the big boss of all the zombies, and appears only in the last level. It's a long fight, and he will annoy with his random throwing of vans, and deployment of bungee zombies, but he also has his weaknesses that can give you the edge.
When he puts his head down, is when your pult-plants can attack him. Use an Ice-shroom to freeze him, and give your plants longer to attack. You can freeze him again when he comes down for a second time, after defreezing.
Before going back up, he will shoot a big ball of fire, or a big ice ball from his mouth. You can break these balls by using either a Ice-shroom (on the fire ball), or a Jalapeno (on the ice ball).