Foggy levels are tricky, but clever use of Planterns and Torchwood will help if you can keep them protected
Sunshine is everything, so don’t be afraid to plant a lot of Sunflowers/Sunshrooms. Two rows should do it.
While harvesting sunshine early on, one neat tip is to put down Potato Mines to hold off the early zombies without having to spend all your sunshine on more expensive plants. Sure, they’re one use only, but at 25 sunshine each, they won’t break the solar bank. Plant them some way in front of the oncoming zombie, though, so they have time to activate.
Keep your defenceless plants at the back. It may sound obvious, but plants with no means to defend themselves should be as far away from the zombies as possible.
Remember, if the worst comes to the worst, you have one free kill per row with the lawnmowers. If reached, they will kill everything in their path. A helpful safety net.
The Wallnut (and its cousin, the Tallnut) can be a lifesaver. If some zombies are getting uncomfortably close to your house, you can put one down to stall them (35 seconds for the Wallnut, 70 for the Tallnut) while you gather up sun-power, dig up defenceless plants and put down a pea-shooter or two.
The Gravebuster may seem a luxury item, but it’s worth using when you have excess sun for two reasons: 1) it gives you extra cash to spend on stuff from Crazy Dave, and 2) zombies pop up from the graves in the final waves – if they’re removed, they can’t.
Speaking of Crazy Dave, save up money and visit him often. Top items include an extra seed slot, and the Sunflower upgrade for double the sunshine per harvest.
You can also use the Wallnut to bottleneck a bunch of zombies at once. Plant a Wallnut, let them gather around it, drop a Cherry Bomb and worry about cleaning up the bits of corpse later.
Another way to bottleneck zombies is using the underrated Garlic, which will send zombies into an adjacent row after a single bite. Putting these on the top and bottom columns can funnel the undead into your four main rows, where you can concentrate all your firepower.
Jalapeños burn not only the Zomboni, but also the icy path it leaves behind.
Joke for you: What does a vegan zombie eat? Graaaaaaaains
Specific Level Tips
Rooftop levels are angled, so anything on the back five columns will need to either be a catapult, or a non-offensive item like a Sunflower. But once the roof is flat, the trusty Threepeater is just as effective here as ever.
On ‘conveyor belt’ levels, whack down unwanted plants, then immediately dig them up to clear space on the belt for prize items.
The bowling levels aren’t too taxing, but as each Wallnut bounces off at an angle from the zombie it hits, you can control which direction it heads by using the bottom or top lanes, where it can only ping off in one direction.
Looking for more?
Need more tips? This is only scratching the surface of the game, but PopCap have a very neat guide in-game. The Suburban Almanac tells you about all the plants and zombies encountered so far. It’s selectable from the main menu. The ‘Help’ button, however (hilarious as it is), is best ignored, unless you’re secretly rooting for the undead.