Need Help with Weight Painting

So I have this grass field using a particle system. Im wanting to place words in this grass field by weight painting where the text is so I can set the paint as the grass length (to make the grass shorter where the text is) this will make it to where you can see the text in the grass field. My question is does anyone know a way to use the text to paint weight where it is on the plane? Or do I have to by hand paint the text? Thanks guys.
http://s27.postimg.org/677r1939v/Screenshot_1.png

Have a look at dynamic paint for weight painting you could get a text object as the brush and use the plane as a canvas then bake the weight paint or something like that.

Alternatively if I understand the question, you could just create the text mesh and shrink wrap it to the plane and have one particle system on the plane and one on the text that might be easier and actually give you more freedom to try out different stuff but you would still need to paint where the text was on the plane I guess to stop the grass poking through. Perhaps use dynamic paint and that.

(or just paint it by hand or just highlight the verts in the pattern you want and allocate the weight etc)