Mandatory

1. Sunflower
2. Potato Mine
3. Lily Pad
4. Squash
5. Tangle Kelp
6. Spikeweed
7. Garlic

Recommended

1. Spikerock
2. Imitater Potato Mine or Imitater Tangle Kelp
3. Cattail

Alternative

1. Wall-nut
2. Jalapeño
3. Starfruit

Most of this demonstration will be made using the Recommended setup with some mentions to the Alternative setup.

Start by planting Sunflowers in one of the lanes instead of the columns. You should have about 3 of them by the time the first zombie rolls up, at which point place a Potato Mine on that lane from a enough of a distance to give the mine time to sprout (you need about 4-5 squares of distance from the average speed zombie at a minimum). I recommend doing it a little closer to the right than the very back column because if another zombie shows up you're going to want the next Potato Mine you put to be behind the one you last put rather than in front of it. If you have an Imitater Potato Mine you can use that to take care of a column as well.


Once you have some 4 or so Sunflowers and the zombies under control, or if a zombie comes up on the lane you picked for the Sunflowers, place a Garlic at the front of that lane. You should have up to 7 Sunflowers on that lane by the time you're done with it, because you're gonna want 2 Garlic there in case the first one gets destroyed.


At this point zombies trickle in really slowly so you should be able to take care of them with the Potato Mines and the Squash if need be. Just remember to only use the Squash on a close by zombie since they can get hit by Peashooters. Meanwhile the Potato Mines cannot get hit by them. Take the opportunity to start putting Tangle Kelp on the pool as well, starting from the right because they can get hit.


Once you either covered each of your non-Sunflower lanes with a Potato Mine or collected a good amount of sun, start placing Spikeweeds on each of those lanes starting from the right. Keep placing down Potato Mines on the left half of the field every time one of them loads up, while building up a sun reserve to add more Spikeweeds. 2-3 on each lane will be enough to kill most zombies, at which point you'll mostly only struggle with the Wall-nut and Tall-nut zombies. You will also have to replace your Garlic every once in a while, especially if a Gatling Pea shows up on your Sunflower lane.


At this point the zombies should have started showing up on the pool lanes. For most of the time your Tangle Kelp will be able to handle it, especially if you've been proactive about pre-planting them, but if you find that you won't have time for another one to charge before a zombie makes it to the other side, slow them with a Lily Pad or put a Squash on one. If you don't have the Potato Mine Imitater you might not be able to use Squashes on the pool on a timely manner either, in which case try slowing them down with a Wall-nut until you can charge up a Tangle Kelp. Beware of Tall-nut zombies; they cannot be destroyed by the damage of a single Squash, but Tangle Kelp take them down in one go. If you have a Tangle Kelp and are torn between using it for a Tall-nut or another zombie, use it for the Tall-nut.

Around the time you have some 3 or 4 Spikeweeds in each lane the tall-nuts should start appearing on the lawn lanes, at which point you should start either upgrading your Spikeweeds to Spikerock, or if you don't have Spikerock put a Wall-nut or Tall-nut right next to a Spikeweeds to keep them on top of it. Watch out for the Jalapeño zombies; they destroy an entire lane if you let them survive for time enough. However if that happens it will likely not happen in more than one lane at once and the excess sun you should have built up will make that not much more than an inconvenience.


Once you have completely filled or mostly filled 5-6 lanes with Spikeweeds in all non-Sunflower lawn lanes, you should now start filling up one of the pool lanes with some artillery: if you have Cattails, place them starting with the left side of the map, with two Garlic covering them on the right, like on the Sunflower lane. If you don't have Cattails, place Starfruit starting with the right, next to the Garlic.


Around this point, if you're using the recommended setup, the game should start playing itself. It is fully possible to reach a setup where you don't need to place down any single use plants anymore. Continue investing on your Cattails or Starfruit and Spikerocks, replace single use plants as needed, and soon you'll get to the end of the stage with your lawnmowers and pool cleaners intact. Final setup will look something like this:


If you use the alternative setup you will never achieve enough damage output that you won't have to use single use plants anymore, but it is still completely feasible to do without much stress.

Q: How does this strategy work?
A: This strategy is devised to minimize rather than withstand damage from zombie peashooters by maximizing the number of plants that can't be hit and sectioning off the necessary ones that can. The Spikeweed and the Potato Mine are the only (useful) plants that cannot be hit by peas, therefore the Spikeweed takes care of the bulk of the zombies which it can hurt all at once, while the Potato Mine finishes off the sturdier ones on the lawn, with the Squash serving as emergency backup in case you don't have enough time to set up a mine. The Cattail and Starfruit are the only (useful) plants that can hit zombies outside of their own lane, therefore the Cattails (or the Starfruit) serve as additional damage output able to be in a completely sectioned off lane, protected by the Garlic that redirects zombies to a lane where there's nothing they can hit, with the Tangle Kelp supplementing its damage needs on the water in lieu of the Potato Mine, with the Squash also being able to serve as a backup here.

Q: What is the alternative setup for?
A: The alternative setup is there in case you want to complete this mini-game before you're done buying all the plant upgrades. It is a setup that requires no Crazy Dave upgrades. In this case, the Starfruit replaces the Cattail as the DPS plant that strikes multiple lanes, the Jalapeño replaces the Imitater Potato Mine or Tangle Kelp as the backup single use plant and the Wall-nut replaces the Spikerock as a way of increasing the damage of the Spikeweed (by keeping zombies on top of it).

Q: Why upgrade the Spikeweeds if there are no vehicles?
A: Spikerocks do more damage than Spikeweeds. I mention it because I myself was not sure they did before I started this guide, so I figure others might not have noticed either.

Q: Do the Sunflowers have to be on the top lane?
A: No, the Sunflowers can be on any row, so long as it's on the lawn, since it's an early game plant and the additional cost and wait time of the Lily Pads makes putting them on the pool an unnecessary extra hassle.

Q: Do the Starfruit have to be on the pool?
A: No, the Starfruit can be on any row, so long as they and the Sunflowers are not both on the pool nor on the lawn right next to each other. The Garlic will never throw a non-pool zombie on the pool or vice-versa, so if you do this they will switch back and forth until they infiltrate your lines and eat your plants.

Q: Can I make more than one row of Starfruit?
A: Yes, but they should not be both on the pool nor on the lawn right next to each other. Same reason as above.

Q: Can I have more than one line of Sunflowers/why is the Twin Sunflower not recommended?
A: Because most plants used in this stage are very low cost, you are likely to start having leftover suns very soon, making Twin Sunflowers unnecessary and more of a hindrance, really. However, you may still want to have an extra line of Sunflowers if you wish to concentrate the zombies more by having one Garlic on each side, so long as you keep the previously mentioned principle in mind.

Let me know if this guide has been helpful to you. If you have any further questions I haven't addressed feel free to ask them in the comments and I'll do my best to answer. Feedback is appreciated.