Marijuana clones is the act of taking a cutting from one plant and growing a new plant from that cutting which retains all the same genetic characteristics of the plant the clipping was taken from. Many people use cloning in order to have a predictable crop rather than taking a chance on different seeds which may or may not end up having the characteristics you are looking for in your new plant. There are three main ways in which growers clone their plants: deep water culture, coco cubes, and aeroponics.
The deep water culture method of cloning is relatively popular due to its ease of use and good results. Many growers report 100% clone survival rates with this system, however each system is different and of course each grower is different. With any clone machine or system, each grower will get different results because of the different environmental factors that can change from grower to grower. Deep water culture (DWC) clone machines work by suspending the new clipping into water or nutrient solution which is constantly oxygenated with air stones. Normally a clipping would drown being completely dipped in water, but the air stones transport the much needed oxygen these clippings need through the air stones.
Coco cubes are also very popular and are considered the easiest system to use. You simply use small coco cubes with a small hole in the top to insert the clipping. The coco cubes are placed into a tray and the tray is typically set on a heating mat in order to maintain the preferred cloning medium temperature of 75-80 degrees Fahrenheit. From here the coco cubes just need to be kept moist and the clippings should show roots within a week for two.
The third and most popular cloning method is using aeroponics. Aeroponic clone machines include the ez cloner and the daisy cloner. These types of cloning machines use the aeroponic system of hanging the plant stem/clipping in air. Water is then sprayed onto the plant clipping in order to maintain as close to 100% humidity within the chamber as possible. By hanging the plant stem into air and spraying water onto the stem, the new clones/clippings are able to get a very high amount of oxygen which helps clone survival rates.
Whichever type of cloning system you decide on, it is very important to maintain a good growing medium temperature and as high humidity as possible. That way you should see success with whichever method you end up using.