The Gargantuar Pirate should be easy to deal with now. However, all lanes have themselves a plank this time, which means the player has to protect all five lanes at once. Luckily, there are no Swashbuckler Zombies or Pirate Captain Zombies, and the frequency of incoming zombies are similar to previous levels.
Start normally. Have at least 5 Sunflowers (recommended to use an another Sunflower from other users for less recharge). You can then plant on top of them for more. Meanwhile, prepare yourself some Wall-nuts and Snapdragons in the second and fourth lane to spread out the damage like in the previous levels.
As the Iceberg Lettuces are free, it can be used for delaying. However, as Snapdragon will remove the freezing effect, this will not be very effective later on. Use it to the first zombies would be effective for delaying at the beginning. (Don't let Snapdragon's fire affects these first zombies until the freezing effect wears off.)
Potato Mines should be used to defeat Conehead Pirates or Buckethead Pirates in the top or bottom row while Snapdragons and Wall-nuts are recharging, which are the unprotected rows and takes the least damage. Meanwhile, plant more Snapdragons.