How do I allocate ram to my Plants vs Zombies Garden Warfare?

Interesting question...

How much RAM do you have?

If you have 16GB or more, creating a 8.5GB RAM Disk you can fit the entire game on it  (it will erease on power off, so you'd have to copy it over everytime).

I have tested this (not with this game specifically) for things before.  Benchmarks look crazy good for a RAM Disk but as far as "improved performance" in games versus a decent SSD.. is non-existant.  For other applications a RAM Disk can be amazingly good.

You can use a program called RAMMap to clear your standby memory... this should "de-allocate" itself though when a program wants more RAM.  Standby memory is just caching what it thinks you might do next, it isn't really in use... Think along the lines of SuperFetch.

http://technet.microsoft.com/en-us/sysinternals/ff700229.aspx

8GB of ram is a sweet spot if you want with most games. I still see many games with a 32bit exe so they all have issues with 2GB+ of ram. Windows by default unless you tweak things can and will eat up 1-3GB depending on your situation. Typical is around 1-1.5 in my experience with most folks. 4GB is fine but may hinder your experience in some games.

So I can't do it directly? How about the command line arguments?

I think 16 or 32GB