1 mother plant
1 pair of scissors
Rubbing alcohol (optional)
Rooting medium of your choice
Rooting hormone (optional)
1 quart-sized Chinese soup container or suitable replacement
1 clear plastic bag
1 rubber band
Rooting cuttings is a task that can range in difficulty depending on the species being rooted. Some plants such as coleus or salvia divinorum are known to root quite readily. They will form roots in a wide range of mediums while being exposed to a variety of conditions. Other plants may either have a high tendency to rot too quickly or are stubborn to send out new roots. Some cuttings can last months until the leaves eventually drop off and the plant dies. This guide is geared towards those plants that will root in a straightforward manner without manipulation of factors specific to that type of plant’s rooting requirements. In other words, this guide will help you learn to root plants that will root under general conditions.
In general, cuttings can be rooted in a variety of mediums. Theoretically, anything that can deliver moisture to the cutting’s tip will work. The better choices will also provide aeration, which may be necessary for some of the less willing plant species. Among the most popular rooting mediums are plain water, perlite, vermiculite, plain soil (or sand) and rock wool.
Rock wool is a synthetic material with a spongy quality that is made of a dense network of fibers. It is used as insulation aside from its use in horticulture and hydroponics. Rock wool has a tendency to produce great root networks. However, the rockwool may have to remain attached to the stem when the cutting is moved to soil to avoid any risk of damaging the newly developed roots. This is especially true for plants with thin roots.
While some growers will choose to root their cuttings in plain soil, it is usually advised to use one of the other options because they are less likely to carry molds and bacteria that could lead to stem rot. But plain soil does have its place. It is generally the preferred medium for rooting cacti and succulents.
Sand tends to be a slightly better choice for most other plants because it lacks the organic material that can harbor pests. But sand can also be denser than some of the other options, which limits airflow and the movement of newly forming roots.
Vermiculite and perlite are both non-organic soil additives that are used to aerate the soil. As rooting mediums, they offer this same benefit. But vermiculite is known to retain more water and be less airy than perlite. For more information on the difference between perlite and vermiculite see our article Perlite vs. Vermiculite: How to Tell the Difference. These mediums are great for both hydration and aeration, and unlike rockwool, they are easier to separate from the root mass and will blend better into the soil once transplanting occurs.
Aside from these other mediums, many growers choose just to root cuttings in plain water. Using plain water will offer no better way of ensuring that the stem tip has a constant supply of water. But water does limit the amount of air that can get to the tip. Changing the water constantly will help increase oxygen content and reduce pathogens. A much more sophisticated way to increase oxygen content in water is to run a fish tank bubbler with an air stone at the end into your water. Some will even use this method with a combination of perlite and water, with the perlite giving something for the root to grow into. While this method may look pretty, it is probably not necessary for most species of plants.
Each of these different mediums has benefits and drawbacks, but when all is said and done, they should all be suitable for rooting a plant such as coleus or salvia. As you experiment, you will eventually come to learn what you prefer for each type of plant.
So once you have chosen your rooting medium, you will need a cutting to root. Choosing a piece to root is important not only to the cutting you’re rooting, but to the mother plant. Since new growth occurs at the nodes (where leaves connect to the stem), you want to make the cutting just above the node so that you leave an area suitable for new growth left at the tip of your branch. If the leaves are in pairs, there is one node on each side if the stem. When taking a cutting, you should keep in mind that snipping a growing tip will cause a plant to split into two growing points, one from each node. Keeping this in mind will give you an idea of how the plant will continue to grow after the cutting has been made. Although you will end up with two new growing points in place of the one, these new tips will be thinner. So you do not want to make too many cuttings in a row from the same tip. In some cases, it may be better to take a side shoot off the main branch if you can find one.
Making a cutting with your scissors is self-explanatory. However, you may want to take the extra step of sanitizing your scissors with rubbing alcohol before making the cut. This will help keep things clean and reduce the chances of infection.
It is also important to select the type of growth that will give you the best chance of success. New growth is the easiest to root. This is most likely because this type of growth is still full of growth hormones. Woody growth tends to be difficult if not impossible (depending on the species) to root cuttings from. So try to avoid it if possible.
The cutting you choose should not have an overabundance of leaves on it because this will just work against you by sapping water from the plant. If your cutting has a lot of leaves, it is a good idea to remove some. Your cutting can only draw in a limited amount of water without roots. The more leaves a cutting must divide that water supply by, the more it will be stressed. In fact, some of the more difficult species to root will only work if you remove all but the top leaves. All too often, people focus on the way the cutting will look rather than if it will be well-established. New leaves will always form, so don’t hesitate to get rid of the baggage before you begin the rooting process.
Once you have selected a cutting, what do you do? Well, first you need to decide if you are going to use rooting hormones. Rooting hormones are not necessary for many cuttings to form roots. However, a trial test (see here) with calea zacatechichi, a plant that is known for easy and quick rooting, has shown that rooting hormone is till effective. Even with a plant that can root very effectively, the rooting hormone showed even quicker rooting and a much more established root network. The most common rooting hormone, which can be found in most garden centers, is indole-3-butyric acid. It is most often seen in powder form. But gel form is better if you can find it since it adheres and remains on the stem better and longer. If you’re against the use of chemicals you can always look into using a tea of willow bark. The alkaloids in willow bark are a natural rooting hormone, which we have used to root mitragyna speciosa (kratom). Since you cannot apply the tea to the stem like you would with chemical rooting hormones, you just use the willow bark tea in place of water, either straight or to hydrate another growing medium.
So now you’re ready to root. Chinese food containers are just an example of a container you can use, but any jar or container that will keep the cutting upright will work. Fill the bottom 2-3 inches of your container with your rooting medium of choice. Thoroughly hydrate the medium. There’s not a lot of technique to this. Just get it wet. If you’re using perlite, you can let a little bit of water pool at the bottom. You want it fully wet. Now, take your clean finger or a pencil and poke a hole in the medium. If you’re using rockwool, you can use something like a BBQ skewer to get a good hole established. Then stick your cutting in the hole you made. If you’re using powdered rooting hormone, wet the cutting tip first before applying the rooting hormone. Then, stick it in the hole. Take your clear plastic bag and put it over the top of your container. Seal the opening of the bag around your container by placing a rubber band over it. This “humidity tent” will conserve moisture so that the cutting does not lose too much moisture from its leaves during the rooting process.
Once your cutting is set up, it is important to leave it in a place that is out of intense light or heat since these conditions have a tendency to stress the plant. Aim for a neutral setting. Some species do have temperature parameters for rooting. But as a general rule, room temperature is fine. To avoid stagnant air, open the top of your tent every few days to let fresh air in. Leave your plant in its rooting chamber until you see a well-developed root network. It is best off in the long run to be patient and wait for a good root system to guarantee a smooth transition into soil. Congratulations, you’re now able clone plants!
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