Level 4

Difficulty

 * 3-layer cats can make it harder. Fortunately, only 15 are required.
 * Every 7 seconds, a new cat pops up
 * Since up to 3 can appear on screen, no doubt of failing it
 * 400 sun should be enough for planting those recommended plants

Strategy

 * Start planting peashooters and sunflowers to make it much easier
 * Don't let the cats scratch your plants