Last time we started talking about how to propagate plants by discussing seeds and the various requirements that sometimes must be met before germination is successful. Today we are going to discuss propagation via cutting. Cuttings are stem or root pieces that are induced to create a new plant.
Propagating plants using this method can be very advantageous for several reasons, however, probably the most important reason is that the new plants will all be identical clones of their parent. There are many valuable traits in ornamental plants that cannot be reliably passed down by seed, and depending on the species, seedlings can be wildly variable and unpredictable. Thus, a clonal propagation method is often the preferred way to produce ornamental plants. The second most important reason perhaps is that many ornamental plants are hybrids that don’t produce viable seeds or have been intentionally bred to be sterile so that they are not invasive. In these cases, clonal propagation is essential.
There are 3 basic kinds of cuttings you might use to propagate plants. Softwood cuttings, hardwood cuttings, and root cuttings. They all have their advantages and disadvantages. Additionally, not all plants can be propagated by all 3 types of cuttings. Therefore, it is important for you to do research or experimentation to determine which method works best for any given species. It is also worth mentioning that not all plants can be propagated via cuttings. Some plants propagate extremely easily this way, others will not root under any circumstances.
Softwood cuttings
Softwood cuttings are fresh young growth. They are what you would get when you are propagating an annual or perennial, and they are also what you get if you take cuttings of new growth off of a woody species in the spring. Softwood cuttings are typically the quickest and easiest to get to root. For many herbaceous plants, cuttings can be taken at any time and rooted easily. However, it is worth noting that for many plants there is an optimum time of year for taking cuttings. Cuttings taken outside of this window may root at a much lower rate or not at all. For this reason, many woody plants are propagated seasonally in the spring using softwood cuttings.
While softwood cuttings typically root more quickly and easily than hardwood cuttings. The downside to softwood cuttings is that ideal conditions need to be met for you to succeed. It can be tricky to keep the cutting from drying out without keeping it so wet that it rots while it roots. Intermittent mist or fog systems are ideal if you’re interested in rooting large quantities of softwood cuttings. However, in many cases home growers can get cuttings to root using a clear plastic bag to retain moisture around their cuttings.
Making and sticking softwood cuttings is easy to do once you understand a few basics.
Cuttings will ideally have at least two nodes. Nodes are the places where the leaves are attached. At the base of each leaf is a bud capable of creating new shoots. Also, you want to make sure you take your cuttings from healthy growth or you will likely fail to succeed. The length/size of your cutting will vary depending on the species, however, the goal is to create a cutting large enough to root but not so large that it cannot support itself. A lot of times this translates to a piece of growth that is 3-4” long.
Once you have cut your branch piece with at least 2 nodes, you want to carefully remove all of the leaves except one at the top. If this leaf is large it should be cut in half or less to reduce the amount of surface area it can lose moisture from. Make sure you keep track of the branch’s orientation. Cuttings that are stuck upside down from how they were growing on the plant typically fail to root.
Dip the bottom of the cutting in rooting hormone and carefully stick it into a moist, airy, sterile potting mix. Then place the cuttings into a humid environment and wait. In a few days or weeks the cutting should have created a ‘callous’ which is a mass of white growth at the bottom of the cutting. This is basically pre-roots and means that your cutting is likely to be a success. You will typically know that your cutting has successfully rooted when it starts to actively grow new shoots from the top node. You can also test for roots by very gently tugging on the cutting.
Hardwood cuttings
Hardwood cuttings are cuttings made from older growth. Hardwood cuttings are often taken in the fall and rooted over the winter. The process is essentially identical to the softwood cutting method discussed above except hardwood cuttings typically do not have leaves on them.
Hardwood cuttings come with the disadvantage that they often take much longer to root, and your success rate might be lower. Less species can be rooted this way and they also typically need higher concentrations of rooting hormones for success. However, they come with one major advantage in that they are much more forgiving of conditions. Because they are dormant, they do not require the elaborate humidity setup softwood cuttings require.
Hardwood cuttings typically benefit from bottom heat (like sitting on a heat mat) which helps them to root. Because hardwood cuttings root very slowly, to succeed with hardwood cuttings your goal is to provide enough warmth to the bottom of the cutting to allow root growth, but to keep the top of the cutting cool enough that it does not break dormancy. Thus you want to keep them in a cool/cold area with gentle bottom heat. If the cuttings break dormancy and grow before they establish roots, they are likely to ultimately fail.
Root cuttings
Lastly, we are going to discuss root cuttings. Root cuttings are probably the least common cutting method, however they are also probably the easiest to execute. Plus, some plant will only propagate via root cuttings so they are worth understanding. Root cuttings are simply chopped up pieces of roots that will grow new plants.
Root cuttings are great in the sense that you chop the roots up, plant them, water them, walk away, and then wait. They require no special care or treatment to be successful. The major disadvantage, as you can probably imagine, is that you have to get roots somehow. This requires you to dig up your parent plant potentially harming it. It can also be difficult to get large quantities of roots to use for cuttings.
That is why hardwood and softwood cuttings are typically preferred methods.
To take root cuttings you dig up your plant, look for large healthy roots (for many plants pencil size is a good size to aim for). Cut them up into pieces a couple inches long and then replant them. Please keep in mind before trying root cuttings, many plants will not grow from root cuttings. Because you risk harming your parent plant we would highly recommend verifying if root cuttings are an option for that species before trying this method.
If you have never tried growing new plants from cuttings, we would encourage you to give it a try. Coleus and Impatiens are great first plants to try with, but once you get the hang of it, it can be addictive. Don’t say we didn’t warn you!
Next time we will be talking about the third commonly used method of propagation, grafting. If you don’t want to miss out on that article, don’t forget to sign up for our newsletter!
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