Link to 100+ Flags gameplay -    • Plants vs Zombies Survival Endless 10...  

Tips Timestamps:

29:48 Tips on when to use Umbrella Leaf and explosive plants
36:42 Tips on plants to bring when there is a Jack in the Box Zombie
42:44 Tips on when to replenish Sun

1) The goal on the first 10 flags is to max your Sun collections. Plant as many sunflowers as possible and don't worry if they get eaten, you'll have gotten profit out of them by that time.
2) Plant the Cattails asap, just two of them can clear out the early waves of zombies. They can attack all rows so really cheap as starting plants. They will also take care of Balloon Zombies and can help attack Miner Zombies. No need to put pumpkins on them, they're cute and they never get attacked.
3) Only need 4 Cob Cannons for this setup, planting on the grass sometimes gets eaten by the imp zombies when they land.
4) The freeze and atomic shrooms are useful in later stages, they can be planted ahead of time and wake them up when huge waves come in.
5) Always check your pumpkin health in the pool. At later stages when there's too many zombies it's hard to check if they're close to getting eaten completely.
6) You can hold out Gargantuars by planting cheap plants (e.g. puff shroom costs zero, sun shroom and scaredy shroom only cost 25 sun)