Mother plants are simply plants maintained to take cuttings from for propagation of future crops.
Unlike most plants which are grown as quickly as possible to harvest, mother plants may be grown slowly for the sole purpose of taking cuttings at a future date.
Therefore, mother plants are generally grown in soil where they won't grow very fast.
As the mother plant grows, count even sets of leaves on each branch. Cut the tip off after three sets of leaves, when that results in the cutting having at least two remaining leaves and one inch of stem.
Put the cuttings into a baggie and place in the refrigerator for about 15 minutes before planting them.
Every where you take a cutting the mother plant will produce two new growths. After a short time the new growths will again present an opportunity to take additional cuttings.
If the first cutting is taken from the top of the plant it will then provide two cuttings during the next "taking". When the resulting two growths have grown they will each allow you to take two more cuttings.
At the next "taking" you will be able to take eight, sixteen, and so forth.
The mother plant will do better if you allow two or three growths to set on each new "branch" before you take cuttings again. Those retained growths provide for the mothers needs so you can continue to harvest from it.
Keep the mother plant in an area where you can provide 18 hours of light per day. A fluorescent light will do nicely.
If you don't provide a long enough light cycle the mother will bloom and you will have to put it back under lights for 18-24 hours per day until it quits blooming and begins growing again before harvesting more cuttings.
Fertilize the mother plant with a very mild mix, you just want to maintain its basic needs.
The mother plant can be maintained for quite some time in a one gallon pot.
Why clone? When you take cuttings from a female plant the resulting plant is a female identical to the mother.