Producing a free and endless supply of herbs from the comfort of your home is not a dream. This can be achieved using a simple technique adopted by many expert gardeners to multiply their best plants. How does it work? This article will breakdown its secret in three science-proved easy steps that you can follow to produce all the herbs you will ever need for you, your family, and friends.
Hence, how can you propagate by stem cuttings your herbs? The propagation by “stem cutting” is by far the most known, easy, and with the highest success rate approach that can be undertaken in three easy steps:
- Step 1: Cut the stem just above a node
- Step 2: Place the cutting in the propagation medium
- Step 3: Transplant the stem once the roots are adequately developed
Now you might wonder, what “herb” should I use? What is a propagation medium? How do I know if the roots are developed enough? Well, keep reading to become a master herb propagator.
Before going to the three-step secret sauce, do you know what propagation by cuttings is? If so, you can skip to the next section. If not, keep reading.
Propagation by cutting is a fascinating process that allows one small part of a plant, in the right condition, to develop a whole new clone (with leaves, stem, roots, etc). It is like cutting off one of your hair and have an entire clone of you after a month! Hence, from one single herb, you can easily originate many many more without spending a single penny.
You need to know that there are many propagations by cutting techniques like stem cutting, leaf-cutting, root-cutting, etc. Some of them are extremely curious like creating a “Frankenstein” plant obtaining by joining the roots of one with the upper part of another.
However, for herbs and houseplant in general, propagation by stem cutting, discussed in this article, is by far the easiest and the one with the highest success rate. As the name suggests, the new herb is originated by the separation of a stem from the mother plant. This approach works very well with a large variety of widely used aromatic herbs, including my favorite basil, mint, and rosemary. Here a list of other herbs that can be easily propagated by stem cutting:
Propagating by stem cutting, once after reading the three-step approach, will be super easy.
Three Easy Steps For A Perfect Propagation by Stem Cutting
To increase your success by stem cutting, you need to know where to cut, which stem, how to nurture it during the root growing period, and finally how to transplant appropriately. This section has you covered unrevealing also a few tricks I learned along the way.
Before proceeding, makes sure you have:
- 1 pair pruning shears or sharp scissors
- 1 Transparent plastic bag or small plastic bottle (like those of 75cl) per stem
- Water (tap water is generally OK, never give me any particular issue). However, for better results (to limit the amount of chlorine), you might opt for distilled water although most of the time the difference is minimal
- Root Hormone: not always necessary (just for the most “difficult” herbs)
- Potting soil and planter (this after a few weeks)
Before proceeding, you need to know what to cut! Not all stems are equal!
Stem cuttings are indeed classified in function of their physical characteristics (color and softness), which, in turn, are strongly affected by age. You need to recognize the stem type you have on your herb, as this will change the type of medium you need to prepare for it (next steps).
However, no worries, that is easy. As discussed in this scientific article, the three stem types are: Herbaceous/ Softwood, Greenwood, Semi-ripe hardwood, and Hardwood.
Types of Stem Cutting: Essential to know how to prepare the growing medium (next step):
- Herbaceous/Softwood: These are the youngest stem, green, soft, and can be bent easily without snapping them. Think about a basil or mint plant, for instance, at their early stage. These have the highest water content;
- Greenwood: It is very similar to softwood, still green in color (although sometimes a bit lighter) but harder and more firm. It can bend but not much before breaking. This stem has had more time to reach this stage;
- Semi-ripe hardwood: This is more close to wood but not there yet. Think to the basil at the end of life (when it starts flowering). Its stems, especially those parts close to the soil, will begin turning brown more woody and hard;
- Hardwood: This has the aspect of wood (if bent, it will break easily). This can be found in trees and all those plants that, in winter, lose their leaves and enter a very low-activity stage. Of course, this will not happen for annual plants as they will die before (such as basil). These cuttings are typically taken in the middle of winter when the plant is totally dormant.
Choosing the wrong stem and, more importantly, cutting in the wrong point will just lead to a rotting stem after a few weeks of needless wait. Let’s see how to avoid that.
For those of you in a hurry, just look at the boxes where you find quick and short steps you need to follow. For those of you, the reasons you have the “Why” section that follows each box. The latter is totally worth your extra minutes as it will provide you great insights on how plants really work!
|Identify a healthy stem: A stem with no wilting/dropping or yellowing leaves and no pests. Avoid also flowering stems.|
Why: An ill or weak stem will have a way harder time to develop roots as part of its energy is depleted by its initial, not optimal state. Developing roots is an energy-consuming process that requires the highest possible energy available.
|Cut the stem: The cut should be ideally from 3-6 inches (7-15cm), starting from the top just below a node. The stem you take away from the herb should start at the bottom with a node.|
Why: A plant node has a way greater ability to develop a new plant compared to other parts of the stem. Indeed, cutting just close to the node stimulates the production of Auxin, as detailed in this study, the hormone that pushes root development.
Avoid cutting a whole stem (starting from the very base of the herb) as well as using a shorter one.
The size of the stem is important because, until the stem develops roots, it has no way to take nutrients from the outside. So the only way to survive until then is to use its internal energy reservoir. A small stem has little energy stored, making it hard to survive long enough and producing roots. On the other hand, a large stem might be too woody at the base (where the roots are supposed to develop), making rooting very difficult (on this later);
|Fix the mother herb: Cutaway the remaining internode in the original herb. You have to cut the original herb above the closest node to the first cutting|
Why: The rule is that every cutting (either in the taken away stem and original plant) should be close to a node to stimulate growth. Indeed, if you leave the long internode uncut, this will end up rotting, becoming a burden for your herb and source of potential diseases.
|Remove the leaves: You need to remove all leaves in the stem except the 2-3 at the top.|
Why: Leaves release water through transpiration. Hence, fewer leaves imply a lower water loss, so the stem will stay hydrated for longer.
Why do we not remove all leaves? Well, if you do that, you will end up with a stem with roots but not leaves to start producing nutrients straight away. You need a few as a starting point.
Why the top ones? Top leaves are the youngest, healthiest, more capable of collecting light and sustaining the stem growth once the first roots are in place.
Tip: some gardeners also cut the leaves in half to reduce water-loss area although, in the case of top leaves in herbs, this is hardly ever necessary (as their leaves are not generally giant)
In this step, I will teach you how and which propagation medium you should use.
The propagation medium is where you are going to plunge the stem to stimulate root growth. After performing the right cut, this is the second most crucial step for success. Choose the wrong medium, and you will end up with rot, slimy stem after weeks of waiting.
Given the variety of stem types, you might have a few kinds of propagation mediums. To create the ideal propagation medium for your stem, you need to put in practice these two principles:
- Limit the water loss to slow down stem degradation. Remember, the stem, until it develops roots, does not have any source of water, if not the one within it.
- Make the stem root before it starts rotting. It is really a battle against time, and all depends on the herb and the stem type (discussed at the end of Step 1);
Option A – Tap Water
Propagating plants through water is among gardeners a controversial topic. Indeed, many might tell you that roots need air to grow. Hence you would expect that a constantly wet medium will always cause stem-rot. This is only true for some types of cuttings and herbs. Indeed, I propagated many times herbs in water with great success. If you do not trust me, just watch countless YouTuber videos showing it.
Which herbs can thrive with stem cutting?
A useful resource on the matter has been written by Thomas DeBaggio, a very experienced gardener that performed a large number of experiments which results are summarised as follows:
Herbs that can be easily propagated in water:
- Mint: root in 6-7 days
- Basil: root in 5-10 days
- Patchouli: root in 10 days
- Pineapple sage: root in 11 days
- Rosemary: root in 14 days
Herbs that will struggle if propagate in water:
- Scented geraniums: root in 26 days
- Oregano: root in a month but only a few roots and weak-looking
- Lavenders: took more than 2 months;
The propagation by stem cutting in water does works for herbaceous, and softwood. However, you will have a hard time for greenwood and upwards and all herbs that are not as “easy-going” as the ones mentioned above. So what can you do? Keep reading
Option B: Potting Mix
A potting mix is generally an option that works better than water, and often the only options for more complicated cases. A potting mix, as discussed in this article, is a soilless mix (there is no sand, silt or clay, here, or more information) that is light and airy. This is extremely important for the success of your herbs.
Then just make a hole in the soil with your finger and place the stem on it (2 cm down the soil level). Then water until the soil is moist but not waterlogged (stop when the water starts leaking from the drainage holes). Watering is essential to provide the moisture the herb needs plus removing to large air pockets.
However, this might not be enough. Some herbs, like lavender, might have quite a hard time even with potting soil. Indeed, they might rot before developing their roots. In this case, what can you do? I have another solution for you, keep reading;
Option C: Potting mix + Rooting Hormones
The success of propagation by cutting is given by the ability of the stems in developing roots. This, in turn, can happen only if the stem can produce Auxin (also called “Indole-3-Butyric Acid”), the plant growth hormone. However, this might not happen for greenwood or hardwood cuttings. Do you have to give up? Not at all.
You need to know that chemistry has advanced dramatically, and nowadays, you can buy such root-growing hormones in convenient powder or gel format from retailers like Amazon (here one of my favorite). What you need to do is just to apply them at the cut base of the stem before plunging into the soil.
Which grow hormone should you use? You can find three types of root hormones based on their “strength” in developing roots. This “strength” is identified by the hormone concentration (IBA) expressed in % (indicated in the label of the product). Lower IBA percentage (0.1%) hormone should be used for herbaceous cut (softwood) while up to 0.8% for hardwood. In your case, go for a softwood version (as we are discussing herbs).
Tip: Before applying the hormone, if your stem is hardwood, just take away (with a knife, be careful) at the base where you cut your stem, the external hard layer. This is a trick among gardener to increase the rooting success by exposing less dry and “active” tissue of the plant.
How to apply the growing root hormone? In case of powder rooting hormone
- Dip the cut terminal first in water
- Put aside in a small container, a small amount of rooting powder (I prefer powder to gel, easier to use) where you dip the terminal of the cutting. Do not exaggerate with the rooting hormone as the excess must be thrown away. You should not place it back in the original container.
Tip: do not plunge the stem inside the rooting hormone container, as shown by some gardeners, especially on YouTube. This, indeed, will introduce moist affecting the efficacy of the hormone in the whole container. Moreover, remember to use gloves when handling rooting hormones.
If you performed the previous two steps as described, this step should be a piece of cake.
However, there are a few tips along the way you need to know if you want to increase the chances of success. We then have two different approaches depending if you used water or potting soil as a propagation medium.
Option A: Water
In this case, just place the water in a glass (or similar) and drop in the stem. The stem should be submerged for around 1-1.6 inches or 3-4 cm. Place the glass on a windowsill but avoid direct sunlight.
The temperature here matters. A (human-conformable) ambient temperature of around 65/70F (18/21C) is ideal.
Options B and C: Potting Soil and/or Hormone
In this case, water is not as abundant. Hence, to retain moisture is highly recommended to place the container inside a closed plastic bag.
Cooler option: place on the soil, above the stem, the bottom part of a cut plastic bottle as a dome-like structure. This will cover the stem, and, from time to time, you can change the air by opening the bottle tap. It also looks cool.
As in the previous case, a temperature of around 65/70F (18/21C) is recommended. This, with the “plastic bottle” approach, should not be challenging even in a colder environment thanks to the greenhouse effect
If not possible, try to place the plant in the warmest corner of your house with some indirect light.
Now that the setup is in place, you just need to wait. The process, as also discussed in this authoritative source, can take more than a month. As a general rule of thumb, you should proceed to transplant your stem in its final container when the roots reach a length of around 1-2 inches (2.5-5 cm).
In case you are propagating in water is straightforward to decide when this happens as you can see the roots. In case you are using a potting mix, you need to lift the stem and check the roots. Given their early stage of development you do not want to damage them, so compared to what I have written here (transplant for a fully developed herb) you need to be extra careful.
Tip: when propagating by stem cutting, it is a good rule to try propagating multiple stems at once. Indeed, not all of them might root.
In case the roots developed in water, the transplant should follow the same procedure already discussed in this article (step 4). In short, you need first to place a bit of potting soil at the bottom of the destination plant container. Then, while holding the stem that you put inside the container, fill the remaining space with the potting mix and gently compress with your hands to remove air pockets.
In case the growing medium was potting soil, there is no need to transplant, at least in the short term, as the potting mix is ideal for herb growth. In case you have a tiny container, I will still wait to let your herb develop a few stronger roots. This will make it easier for them to withstand transplant stress.
Tip: You should always use a clean (possibly sterilized) plant container to avoid the spread of diseases that might have survived in the pot.
To be 100% sure just wash the container using 2 cups of bleach for each gallon of water and gently wipe the internal part with a sponge. Of course, avoid any direct contact with the solution by using gloves and wearing protective glasses. Once your container is completely dry, you can transplant the stem.
If you read this guide should not be challenging to propagate your favorite herbs successfully. However, talking with a few gardeners, I noticed six common mistakes in propagating by stem cuttings their herbs. Check them to see if you did any of them?
This is by far the mistake #1.
When propagating cuttings in water many leaves the stem in the shiny glass of water for way too long, even after the roots are above the 1-2 inches recommended.
This is not a wise decision because the roots might start rotting, as mentioned in this article, developing a slimy layer on top, due to bacterial infection. Why? Lack of oxygen at root-level, creating the best environment for root-rotting bacteria and fungi.
Another problem caused is the development of a large number of roots. These will get entangled easily susceptible to damage one transplanted.
- Change the water every 2-3 days to replenish the oxygen level. This also has the advantage of avoiding the formation of algae (not a massive problem, just not beautiful to see). Important to be at room temperature
- Place a reminder (Google Calendar for me works like a charm) after 2 weeks of placing them in water.
- Place one or two stems per container. This will avoid root intertwin, facilitating the transplant.
Not all herbs are suitable for propagation by stem cutting. The following show little chance of success:
- Cilantro: it is known among gardeners to be a tough one. Not impossible to grow from cuttings, but I would avoid it, especially if you are starting out in propagation;
- Dill: this is another herb that is known among expert gardeners (here a discussion) to not root from cuttings, so something that is not worth attempting.
- Chives: they struggle from cutting. However, you can grow them quickly from the bulb.
Within the same herb, you might have the option to choose a hardwood or softwood cutting. The most classic example is the rosemary.
The same stem might indeed have hardwood and softwood features. A cut made at the base will be woody and brown in color (hardwood or semi-hardwood). However, the same stem, a few centimeters above, might be green, soft, and pliable (softwood ).
A cutting starting from the woody party will have a hard time to develop roots. It might take months, or not root at all. To increase your chance of success, you might need to use root hormones and growing such stems in a potting mix, while a softwood will root with just water and in less time.
- Avoid the semi-hardwood and hardwood of the herb if you can by taking the cutting at the early stage of development (spring). Otherwise, you can use root hormones and take multiple cuttings to increase the probability of success
You might be tempted to cut the stems of your fragrant basil or mint with your fingers/nails. After all, it is a softwood very pliable. This is a bad idea. Avoid using your fingers to cut the stem. Indeed, a battered stem can struggle in producing roots.
- Use sharp pruning shears or scissors. Avoid knives as you might damage the mother herb (and they more dangerous to use).
Well, you understand the importance of using sharp pruning shears for a clean cut. However, you perhaps do not know that you also have to sterilize the pruning shears or scissors.
This is especially true if you use the same pair of scissors for indoor and outdoor gardening. Indeed, pruning shears for outdoor applications might carry harmful bacteria, fungi that can be so transmitted to the stem cuttings.
- Use a sponge soaked with a solution of bleach and water (2 cups of bleach for 1 gallon of water) to clean the blades of your scissors/pruning shears. As stated before, use gloves and protective glasses.
Surprisingly, as detailed in a detailed report from the University of Arkansas, the cuttings should stay in a room with an ambient temperature of around 60F (16C) and a rooting medium of about 65F (18C).
However, I have to say that, even without following such strict guidelines, I did not have any difficulty in propagating basil, mint, and rosemary. Nonetheless, for more challenging herbs, this might make the difference between rooting and rotting, so watch out!
- Of course, having two different temperatures is challenging. One way to achieve it is to use heating mats to keep the rooting media warmer. Some suggested to place the container on top of a heater but this can be counterproductive as the roots can get too hot. Moreover, this is unsafe for the user, so it is something that I do not recommend.
Do you need a greenhouse for stem propagation? Although a greenhouse can help in maintaining the humidity ideal for stem growth, it is not necessary. Plastic bags or any other inexpensive plastic object that can be used as a dome will fit the purpose.
Do you need to add nutrients in the water when propagating by cutting? No, in general, for those herbs that can be easily propagated in water, there is no need to add any plant food on it. Indeed, the stem would not be able to use such substances anyway due to the absence of roots.
What is propagation by leaf-cutting? It is a type of propagation that allows developing a whole plant starting from a cut leaf, rather than a cut stem. This is possible for a limited number of plants, compared to stem cutting. Leaves suitable for this type of propagation are usually large and thick as those of succulents (well-know for this propagation technique).
21 Tips to grow massive basil – https://yourindoorherbs.com/21-easy-tips-to-grow-massive-basil-indoor/
Recipe for the best potting soil – https://yourindoorherbs.com/2-aspects-of-the-best-potting-soils-and-diy-recipe/
Video on propagating Basil in Water – https://www.youtube.com/watch?v=Rg1336sO4Uc
Interesting document on propagation from the Purdue University Cooperative Extension Service – https://ag.purdue.edu/hla/pubs/HO/HO-37.pdf
Propagation by stem cuttings from Iowa State University – https://content.ces.ncsu.edu/plant-propagation-by-stem-cuttings-instructions-for-the-home-gardener
An informational guide on stem propagation from Purdue Univerisity – https://www.purdue.edu/hla/sites/yardandgarden/extpub/new-plants-from-cuttings-text-only/
30+ years gardener discussing why propagation via stem cutting does not alway work – https://www.quora.com/What-causes-some-plants-to-root-when-cuttings-are-put-in-water-but-not-others?awc=15748_1572087742_9b79f36ea8afc60c99eef4df20ce837e&uiv=6&txtv=8&source=awin&medium=ad&campaign=uad_mkt_en_acq_us_awin&set=awin&pub_id=101248
Propagation by cutting from the University of Missouri –http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/rooting-cuttings-in-water.aspx
Propagation by cutting suggestions from Suncrest Nurseries –http://www.cruzcnps.org/PropagationHandbook-SantaCruzCountyCNPS-min.pdf
Propagation by stem cutting report from the University of Arkansas System – https://www.uaex.edu/publications/PDF/FSA-6024.pdf
Training manual on Propagation Techniques of Commercially Important Medicinal Plants – http://cropsfordrylands.com/wp-content/uploads/Propagation-Techniques-of-Commercially-Important-Medicinal-Plants.pdf