They generally believe (for varying reasons) that there is something bad or less beneficial about buying mainstream products or doing other common activities in the mainstream way.
You might be a crunchy mom if you:
...bake all your own bread
...make your own jam, jelly, pickles, applesauce, etc.
...gave birth at home -- by CHOICE! (With a midwife, doula, or unassisted!)
...prefer to teach your children yourself at home instead of letting the public or private schools do it for you.
...grow your own food as much as possible, and buy the rest at farmer's markets or health food stores.
...are vegan or vegetarian.
...choose not to use birth control.
...don't wear a bra or shoes.
...don't use shampoo or soap, but instead maybe sea salt or a variety of other things.
...had your placenta chopped up for an anti-depressant pill or smoothie.
...have no television in your home -- and actually read BOOKS for entertainment!
...grind your own grain to make your own bread with (did you know that wheat looses about 90% of it's nutrients within 7 days of being ground?)
...don't cut your hair or wear pants (not going around half-naked, but wearing skirts! Silly people! Get your mind out of the gutter!)
...can add 10 more things to this list that I didn't even think of!
If it were a spectrum, on the extreme far end you would find Amish.