Stuck on Survival Fog

I've been playing the videogame Plants vs. Zombies for a while now, but I'm currently stuck trying to complete the "Survival Fog Hard" level. I need to complete that level to unlock the general survival mode.

I'm also pretty bad at the vasebreaker mode. I need to survive 15 rounds to win an "achievement", but so far my best is surviving two rounds. Yup, just two rounds. The achievement might be a long ways away.

Fortunately, the game gives you plenty of other things to do if you're getting tired of losing on a particular round. I've gone back and done the regular mode again, I'm nearly done with my second round of that. I also play the minigames from time-to-time, but I find them less interesting. Although ones like walnut bowling are so different from the regular modes that I do play them for a change of pace.

I also spend a bit of time tending my zen garden. When you are in that mode of the game, you just water and do other things to care for your plants, and they throw off coins instead of oxygen when they are healthy. And I have a snail to help me collect the coins. It doesn't make much sense, but it's just a videogame after all, and the music during the zen garden screens is pretty soothing.