I've been down to two achievements in Plants vs Zombies for almost 2 weeks now. I've been playing when I can. That endless wave is a little rough. I was trying to use a strategy on TA but it only got me 24 flags the 2 times I tried it, so I gave up on it. You've got to have stuff to stop the bungee zombies. If not, they will take your stuff and mess you up.
At the bottom of the post, he posted another picture of what someone else said was a better setup. Plus it easier on cost to make happen. I've been rolling through with it and I'm almost to that point where I hit 24 flags again. It has been working pretty good and the cost to set it up was a lot lower than the other method. So getting it fully setup early on helps out. Definitely can't wait to see how much crazier it'll get after 24 flags and it's crazy enough already.
One thing I've been doing that wasn't in the picture was putting the spikes down to help stop the zombies on wheels. When they come in, you have one laying down ice that also flattens everything it runs over and the other is throwing stuff to take your guys out at the back. I put it on the 2nd row in from where the zombies come in but I'll probably add it to the front 2 rows when they come in as it will take them out quicker that way. Plus it hurts the other zombies. Only bad part is the gargantuan zombie that comes out will smash it with his club until it breaks. At least it does help slow him down while everything else is taking him out. Plus the spikes hurt all the zombies, so nothing like spending money to help me out more and not just setting there gaining and not spending anything outside of the ice plants to freeze the zombies.
Since I'm almost half way to where I usually get my brains eaten, I've been constantly using the ice plant to freeze all the zombies on the screen. I'm glad to have that duplicate plant so I can put 2 down of the same plant as it helps being able to regenerate it faster.
The other achievement involves the tree of life. I just sold my 2nd set of plants in my zen garden and used it all to buy fertilizer for the tree of life. I got it up to 81 feet before I ran out of money. I figured if I could make through endless mode and then sell everything else at that point, I should have enough to finish it off.
So maybe if I'm lucky, I'll finish this game off this weekend at some point if I can make it through 40 waves of zombies.