Okay so this is where we cue Doctor Frankenstein's lab. The doctor cackles madly and the lighting strikes just as he switches the lever. A moment later there is grunting from the form under the blanket and the doctor screams "It's alive!!!"
Or maybe not. Cloning a plant doesn't require a cleanroom, it doesn't require a lab. No men in white coats, no special chemicals or treatments. No high school biology let alone a degree. People have been cloning plants for thousands of years and its extremely easy to do. The simplest way to clone many plants is to cut off a piece of a plant and toss it in a glass of water. Stick the glass in the window, wait a few days and presto roots will sprout from the bottom of the cutting. At this point your cutting is now a clone of the plant it was cut from. For plants cloning and regeneration are a process that is completely natural. It happens to them regularly during the simple rigors of existence.
Cloning is the process of replicating the exact genetic characteristics of a plant. If you have found not only a good strain but a particularly fine specimen you can share it by cloning. Or you can keep the fine plant in the vegetative stage forever and only grow out and mature cuttings of it. Not only do you have a plant with known properties such as potency, potential yield, disease resistance, size, etc but you will be able to have a garden of plants that given the same conditions will more or less grow at the same rate and respond to the same way to different training methods. Your plants will all have the same nutrient requirements as well.
Cloning is also an ideal way to determine the sex and properties of potential mother plants without every having them undergo the stress of flowering. This is much better than taking a cutting during flowering or putting a flowering plant back under a longer light cycle to revert it back to vegetative growth. Stress can alter or damage genetic material and that genetic change will be passed to the cuttings taken from the mother after that point.
Rooting hormone is completely optional. It often comes as a gel or powder that you apply to the base of the stem of your cutting to stimulate root growth. An alternative that seems to yield excellent results when compared to plain water or commercial rooting hormones is a dip in aspirin water. Just crush up two extra strength aspirin in a half liter of distilled water and let sit with occasional agitation overnight. Now dip your stems in the aspirin water instead of rooting hormone before putting them in the medium and you will have excellent results.
When you take cuts you are going to need to do something with them to keep them in ideal conditions until they grow roots. Obviously you will put them into a medium but then what? Here are a few devices used for this purpose.
Two Liter Bottle Method
This is probably the cheapest and easiest consistent method to root a small number of clones. Just cut the bottom 40% off a two liter soda bottle put a clone in rockwool or a whole small jar with another medium inside the bottom. Cover with a plastic bag and hold the bag down with a rubber band. Before sealing give it a puff of exhaled air to fill it with CO2.
This traps humidity and it is normal and desirable for moisture to condense on the container. You will need to exchange air every day until roots appear.
The most common tool used is the humidity dome. These can be purchased for $10-$15 U.S. Dollars at any hydroponic shop and consist of a plastic tray that is just the right size for a sheet of small rockwool cubes to fit inside of. There is then a clear plastic cover that fits on top of the tray to trap humidity. Depending on the number and size of clones you will need to exchange air between 1 and 3 times a day.
These can be purchased or constructed. Essentially this consists of a tray with a cover. In the cover there will be numerous net pots and in the tray will be water and aquarium air stone strips. The strips bubble air through the water causing the bursting bubbles to moisten the medium in the net pots. These can be used with or without a humidity dome cover.
These simple and prolific cloners are generally constructed rather than purchased. A system similar to the bubbler is used with a tray and cover. Instead of net pots the tray has half pint plastic containers suspended over the water. A wick, usually a 1 1/2 inch piece of shoelace or strip of cloth then goes from a hole in the middle of the bottom of the container down into the water. The containers are then filled with perlite. The wicks pull up moisture into the perlite. A dome cover is not used with this method.
This is the easy part. You will want a pair of sharp scissors and a cup of water handy. When you take a cut put it into the water immediately. Cuttings should be about four inches long, and the cut should be placed about 1 cm below a node. You must have a growth tip to take a cutting and will want a couple nodes past that.
After you have your cuttings take your glass of water over to a sink. You will need a sharp knife or razor for this step. You should prep and plant each cutting entirely before moving the next. Remove all leaves except for the top set. Clip the leaves on the stop set so long, that half their length is present. Place the stem of the cutting under water either submerged in a pool of water or under a stream in the sink. Cut the stem at a 45 degree angle. This prevents air bubbles in the stem that would prevent moisture uptake. Finally score the bottom 1/4 of the stem. You only want to score the skin of the stem and not cut into the stem itself.
Planting the Cuttings
Dip your prepared cutting into asprin water or any rooting hormone you have (if any) and then plant in the container and/or medium you will be using. Try to plant all stems approximately the same height and just enough to give good purchase in the medium.
That's it, use one of the aforementioned systems to care for your clone for the 7-14 days until it grows roots (yellowing in the leaves is often a sign that roots are developing). Not everyone will have 100% success so take extras cuts. This lets you pick the healthiest clones. After roots form you should plant the clones within 7 days and feed only 1/4 to half strength nutrient until they are healthy (about 7 days after rooting). Clones should be treated like seedlings. One major difference is that clones are sexually mature as soon as they root and can be flowered immediately if you so choose although most growers give them a veg period.
Replacing your mother with a fresh clone from healthy tissue often will reduce genetic damage due to stress and replication failures over the life of the plant. Over the course of time genetic damage will occur within any organism and your mother plants are no exception. While plants are very resilient to this particular type of damage it still occurs. However, this type of damage is often localized and a clone taken from an undamaged portion of the plant will contain the original genetic profile. This clone can then be grown and cultivated a replacement mother plant with no adverse effects because it contains the same genetic code as the original mother plant. This is true no matter how many generations of mothers from mothers you take.