How do you plant a cactus starter?

cactus can pretty much "root" by just laying them on top of moist sand or dirt. I have a form of cactus sitting on a concrete bench. If a "petal" falls onto the concrete,it will root right there,and a little rain just keeps it alive. Remember, they are made to live in the desert. They will send out roots through rocks,sand, even concrete in search of water. They "hold" water.Give them desert conditions. Too much water is not good either. They'll turn to mush.

generally a cactus falls into the succulant category and like succulants they can be started by placing a healthy piece of the plant directly into the ground or into a container with dirt - the only thing is try to make sure that the dirt contains quite a bit of sand/and or gravel....you usually will never notice them looking any different until they actually start producing offspring - either by the side of the cutting or as a "bud" - breaking the cutting off rather than cutting it off is better for a "starter."

i have alway just stuck them in the ground about 2 inches under the soil. but if its going to get huge you might want to go deeper. i have always found that cactus plants love to be neglected. im a bad over waterer.