I can teach ya, real simple in fact.
1. go to the fh folder, then media, objects, plants.
2. Click on one of the flower png files, edit with gimp.
Gimp, is an easy tool use to color presets, retexture and all things like that, which you can download it here
http://www.gimp.org/3. After that open it up and go to the black colored and go to red, click the paint brush and lower the opacity to 70 or lower
4. make the brush larger
5. color
6. save and go in game and type in the flower [number here] mesh in object creator and walla!