The Fastest Way to Root Clones

We all love plants, and happily devote our time and energy to nurture them. Be it for their beauty, their nutrition, or their commercial value, growers are always looking to increase the size their gardens. But the expense of buying new plants adds up quickly, and for some growers, the initial investment for several dozen plants is an intimidating bite out of their budget. There is also the fact that plants of the same species vary slightly in their genetic makeup, and it is unlikely that every plant in a bulk purchase will match the exact traits of the single plant that made you fall in love with that strain in the first place. Fortunately, horticulturists have been developing the cloning process for generations. And the sooner you learn the fastest way to root clones, the sooner you can have vast quantities of your favorite plant!

What is a clone?

 A clone is a plant grown from the cutting from another plant. It is genetically identical to the original plant (commonly known as the mother plant). Plant cloning is a common method used to produce a large amount of plants with the exactly the same characteristics. Growing a clone instead of starting a new plant from seed has two advantages. The first, obviously, is that the clone will reach maturity faster than one starting from seed. The other advantage is that you know exactly what you are getting — same taste, size, hardiness, color, or any other attribute you love about your mother plant.

Cuttings should be taken from a mother plant that displays the traits you seek. The plant should be mature enough to be robust, but not so old that its growth has become woody. Check for pests and disease, as anything you bring to your cutting room will infest your clones. Your success will be determined by the type of plant you use, your method of taking a cutting, the environment you grow them in, which nutrients you feed it, and how you apply these nutrients. Get all of these variables right, and you can claim the title of ‘Clone Master’!

Root clones faster
Photo by Severin Candrian

TAKING A CUTTING

A fast rooting clone begins with a good cutting. Begin your cut below a growing node. 

Depending on the plant you are growing, you may have two or three intermediate nodes between the top and bottom. Strip all but the top set of leaves. A number of growers go a step farther and clip the tips off of the remaining leaves. Monty Don, host of BBC’s wildly popular  BBC’s Gardeners’ World, is a proponent of clipping the leaves. “The more leaves it has, the more moisture is lost.” 

However, Monty’s opinion is not universal. According to the International Plant Propagators Society there are reasons NOT to cut the tips:

  • The cut causes a wound that is open to infection.
  • The cuttings have reduced natural rooting substance IAA [an auxin]
  • With a wound present, the cuttings use valuable resources to heal, rather than induce root formation.

So what’s the best method? Likely, the answer lies with the specific plant and its immediate environment.

Once you have made the cutting, it begins losing moisture right away. To protect it, you must either plant it immediately in the growing medium of your choice, wrap it in a clean, damp cloth, or put it in a plastic bag.

Cutting techniques

There are some subtleties to making the best cuttings. The base should be cleanly cut. Common wisdom says to cut at 45 degrees in order to maximize surface area for new roots, but some growers have found success with two alternatives. The first alternative is to cut straight through the stem; studies have shown that with many plants, this 90 degree cut is as effective as the 45 degree cut. The next alternative is to split the stem lengthwise for half an inch or more. This newer method has in some cases resulted in a remarkable improvement in the number of new roots on a cutting. Experiment with the specific plant you are trying to clone, and you will find the best cut to make your clone root robustly.

Should you score your cutting?

Scoring the basal node increases the exposure of the cambium layer — the layer that new roots grow from. Some growers claim success with this method. Scoring has its drawbacks: handling time and exposed area — both vectors for contamination. Also, the improvement in root growth is generally nominal, so unless you are having trouble getting roots, scoring does not seem to be worth the effort.

Can You Clone A Flowering Plant?

Although a cutting can be taken at any time of year, you will have the most success if you do not take them during the flowering stage. The plant has already directed energy and nutrients to the bud, and it will be difficult to compel the cutting to redirect these resources to root growth. The plant chooses where to put its energy, and reproduction will take precedence.

The importance of sterile tools 

When taking cuttings, you need to use sterile tools. You are performing surgery, and some of the same dangers that animals face when undergoing surgery are dangers to plants. Fungus, bacteria, and foreign bodies can enter the cutting and kill it. Dull blades may tear rather than cut, thereby crushing the tender cambium layer. A small investment in sharp shears or a hobby knife is an investment too simple to ignore.

For more detail on how to take cuttings from various kinds of plants, visit a Purdue University extension

Fastest Way to Root Clones

Now that you have your cutting, you need to put it in a growing medium. From water to wool, to gel to compost, a range of media can be used to help your cutting take root and become a proper clone.

Cloning Plants In Water

The simplest and oldest method for getting cuttings to grow roots is to submerge the basal node in water.

Hydroponics and nutrients

Success with cloning in water is increased exponentially with the addition of nutrients and root-growing hormones. A number of specialized growth formulae and media are made specifically with hydroponic root growth in mind.

Best Cloning Medium 

Rooting clones in water can be done with water, some plants have low success rates. Your cutting is about as likely to rot as it is to sprout roots. As one gardener lamented, “Most of my failed clone attempts failed because the stem stays wet, gets soggy and collapses.” If you are serious about your rooting your clones, you need to support your cuttings with a solid medium

The ideal medium varies with the type of plant. But by following the following guidelines, you will be able to formulate the medium that will make your clones root the fastest.

Peat, coco coir, rockwool, perlite, and compost are the most common cloning media. Although rockwool does not occur naturally, all of these media are made of natural ingredients.

Peat

Peat is a very common medium, often sold as disc-like ‘pellets’ held together with a slender mesh. Adding water causes the pellets to expand and become ready for your cuttings. Peat is known for having a neutral pH; however, has few nutrients, and tends to dry out quickly. Additionally, if you do not cut away the netting when planting, peat pellets will strangle your growing roots.

Rockwool 

Rockwool is made by combining basalt rock and chalk under high heat. It is inexpensive and easy to find. Rockwool works well with hydroponic growing, as its highly absorbent nature makes it easy to get nutrients to your rooting clones. There are a few drawbacks, however. Rockwool does not decompose. When new, it also sheds dust and thin fibers which can irritate the lungs. Growers who use rockwool on a large scale should wear appropriate protective equipment

Coco coir 

Coco coir is made from the husk and hairs of coconuts. It is light, inexpensive, and retains moisture fairly well. Like rockwool, coir works well in hydroponic systems. Because it is grown in ocean climates, coir may have a salt residue which may affect pH.

Perlite and vermiculite

Perlite (a type of obsidian) and vermiculite (a mica-like mineral), are often used in conjunction with one another. They both assist in aerating the soil and making it less compact. Perlite absorbs almost no water, while vermiculite holds a good amount of moisture. They are often used in conjunction with compost or coir.

Compost (soil)

Sometimes the best medium is prepared soil. All the necessary hormones and nutrients can still be delivered to the clone, though perhaps without the precision of a hydroponic setup. Well-composted soil has the advantage of microorganisms to aid in root growth

The Right Environment for your Cuttings

Once you have your cuttings settled into the growing medium of your choice, you need to set them up in an environment to thrive. Controlling the heat and moisture is essential for your clones to root. Tender cuttings should be covered in plastic to retain moisture. Heat mats should be used if you are growing in a cool place. Grow lights are essential in order to provide consistency. Fluorescent lights are common. LED lights are more efficient, and you can choose precise ranges of wavelengths. However, if LED lights get too close, they can damage the cuttings.

Plant Hormones

You’ve taken your cuttings and successfully planted them in a root-supporting medium. Now, what will you feed it?

Auxins: The Plant Hormones

Plant hormones related to growth are called ‘auxins’. Of the auxins, one known as IBA (Indole butyric acid) is most closely tied to root production, with NAA (naphthalene acetic acid) a close second. These hormones can be collected from natural sources or synthetically produced. If you are purchasing synthetic rooting hormone, be sure that it includes IBA or NAA.

Dutch growers were the first to use commercialized auxins as a propagation aid in the mid 19th Century. The method became widespread in North America a half century later. (Kroin, 4) Modern cultivators have a plethora of scientifically formulated products designed to feed your clones the root-growing hormones you need.

Applying Root Growth Hormones

No matter which root-growing supplement you choose, you need to apply it correctly to your plants. There are two distinct methods to applying the hormones: basal and foliar. As the names imply, one is an application to the base of your cutting; the other method is to spray the supplement on the plant’s foliage. 

Basal application requires you to dip the basal node of your cutting into either a water solution or a gel. Water solutions are best for hydroponic systems, while clones planted in soil would do better with a hormone gel. Powdered auxin is dissolved in the water to create a solution, and gels come ready to use. Apply the hormones to the cutting, not the cutting to the hormones!The Missouri Botanical Garden has an excellent visual guide to basal application.

Foliar application works because the stomata at the base of the leaves absorb the auxins as they ‘breathe’. You can spray the leaves 12-24 hours before cutting; this will give the hormones time to travel into the stem and nodes. Foliar application after planting the cutting may work well — but if nearly all the leaves were removed (for reasons discussed previously), you will be working with a limited surface area. The International Plant Propagators Society published a thorough explanation of both basal and Foliar mechanics.

Experimental methods

Most horticulturists are given to scientific experimentation of some kind or other, and those who experiment with substances to promote root growth in clones are no exception. For those of you who want to reach deeper into the possibilities of basal applications, you may want to try a heavily diluted solution of honey or apple cider vinegar. Their antibacterial properties can protect the cutting from infection, thereby increasing the clone’s odds of survival.

Match your Methods to your Plant

Every variety of plant will have slightly different needs. Nevertheless, there are a few guidelines that will improve your cuttings’ success. Adjusting the principles of root growth to your chosen crop is essential to maximizing your success. 

As a rule, cuttings from herbaceous and softer-wood plants will sprout roots more quickly and easily, and require more warmth and moisture. The cuttings will rely on photosynthesis for its energy needs. Take cuttings from softwood plants early in the growing season, before buds form.

On the other hand, hardwood cuttings will be slower to root. Their energy will come from woody stores rather than sunlight. Take cuttings from hardwoods late in the season, after fruits and leaves have fallen.

The Payoff

Learning how to quickly root your clones and keep them healthy means a virtually endless supply of your favorite strain of plant. Once you learn the art of cutting and caring for clones, your garden’s growth potential is unlimited. Happy cloning!

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