One of the many things that drew me to horticulture is the witchcraft of plant biology. There are so many intricate and complex processes going on that power plant growth, life, and reproduction. Part of the beauty in being a biophiliac is that you don't have to know the ins and outs of plant physiology - how cells divide, how genetics work, plant hormones - to be endlessly interested in and fascinated by them. That being said, I chose to get a degree in horticulture so that I could have an excuse to spend 4 (okay 5) years getting real familiar with how plants work, and the more I learn the more amazed I am. And then every time I successfully root a cutting, that curiosity and captivation is reinvigorated!
Propagating plants is one of the most rewarding parts of keeping houseplants!
Think about it - what are your favorite things that happen with your plants? My guess is that one of them is when you see a brand new baby leaf popping out. Propagating is that rush, but on steroids. When you cut a plant into pieces and root them, not only do you get to experience the magic of a plant completely healing its wounds and putting out roots from outta nowhere, you also get to multiply your plant collection. For freeee.
In this post, I will mostly be talking about propagation from cuttings as that seems to work best for me, and it's the method I know most about. Cutting propagation is also most common method used for houseplants. Other propagation methods include from seeds, by air-layering, and through division, but I'll let someone else's blog talk about all that.
Anatomy and Physiology Basics
Propagation can be pretty simple once you get the basics of plant anatomy and physiology. In this section I'm going to let you in on a few of the secrets behind the magic of plant propagation!
Meristems and nodes! If there is one thing you take away from this post, I hope that it is something about meristems. They are the growing points where meristematic cells exist and actively divide, creating new growth. There are meristems in the root and shoot systems, but the meristems we are concerned with exist in the shoot system. The apical meristem is the growing point at the end of a branch, where the newest leaves are coming out. We work backwards from this point to find where we will prune or take cuttings. There are also lateral meristems, which are found in the axillary buds of leaf nodes. A node is where a leaf intersects a stem. This is where the magic of propagation comes in with simple leaf cuttings.
If the apical meristem is removed, the flow of a plant hormone called auxin changes. Auxin contributes to apical dominance by inhibiting lateral buds from growing and keeps the plant growing upward from one main stem/leader. So, if your plant is getting leggy and you want a bushier form with more branching, you cut off the apical meristems of the shoots to promote lateral growth! This will happen both on the original plant and on your cutting.
You can see an example of this in this picture of one of (the hundreds of) cuttings I've taken off my Tradescantia. The wound at the top where I cut this piece off of the rest of the stem healed over, and a lateral bud in the leaf node took over to become the new shoot system.
The node is also where you will get adventitious roots to form to support your new plant. Adventitious means that one tissue type is arising from a different tissue type, in this case root tissue growing from stem tissue. Auxins promote this type of growth which is why they are called rooting hormones, marketed as Rootone. Using synthetic auxins, along with controlled wounding like scraping and slicing can be helpful if you are working with cuttings from a difficult-to-root plant species, like woody plants. But, be sure to not use too much Rootone, as it can inhibit the lateral bud, and you won't get shoot growth.
So, to get on the fastest track to getting a successfully rooted stem cutting, you want to keep at least one node for shoot development, and at least one for root development!
In plant species with long petioles, aka the stalk that attaches the leaf to the stem, you can have a cutting with only one bud that will produce both a shoot and roots. A good example of this is with pothos, as shown below. The petiole is long enough to keep the bud submerged without the leaf blade being in the water. Pothos are also generally pretty easy to root, so I left each cutting with only one node.
One case where you don't need to have a bud to propagate is with leaf cuttings. In this case, only the leaf, with or without its petiole, is used to propagate a new plant. This process relies not only on the formation of adventitious roots, but also adventitious shoots. In this case, the original leaf has no real future - it only serves as a provider of cells. Do not use auxins on leaf cuttings, as it will likely inhibit shoot growth. Leaf cuttings only work with a limited number of species. One of those is Sansevieria, and I plan on doing an entire post dedicated to Sansevieria propagation very soon, so hold tight!
Variegation and Reverting
One reason that cuttings are the most popular method of propagation for houseplants is that they result in genetic clones of the mother plant, as opposed to seeds which introduce genetic diversity through sexual reproduction. Many plants that are loved as houseplants are prized because of their variegation. Variegation is when a plant exhibits multiple colors in its foliage - usually a fascinating mixture of greens, white, yellow, pink and purple. My absolute favorite plants are virtually all variegated - the contrast of colors add depth, texture and interest to landscapes and living rooms alike.
But the drawback of the added beauty of variegation is the issue of reversion. Variegation is caused by a genetic mutation that results in non- or differently-pigmented cells, and often that mutation is not all that stable, so with light and temperature fluctuations, the plant can revert back to a more stable genetic state, aka all green. The pigment that produces green cells, chlorophyll, is the pigment that allows plants to photosynthesize and get produce energy from the sun. Leaves with more chlorophyll will produce more energy for the plant, and are therefore favored.
If your variegated plant is not getting enough light, it will likely start to revert back to an all-green version of itself in order to produce more energy. Once reversion starts, you cannot reverse it within an individual shoot.
The ways you can deal with reversion are preventative and through control. Provide enough light for your variegated plants. And inevitably, when you do get some reverted shoots emerging, catch them early, and cut them back before the plant has used too much energy to produce them. With my variegated Tradescantia, I am constantly fighting reversion even though she gets the most light of any plant in my home. I cut out her all green stems, and simply propagate all the cuttings for a fully green version of the plant.
The reason I bring up all of this stuff about reversion in this post is because the instability and inefficiency of most variegation means that the variegation will not hold true through sexual reproduction by seed, and must be maintained through clonal cuttings. This is part of the reason it is so rare to find variegated plants in the wild, so don't take your colored leaved for granted!
These are some of the variegated pothos and satin pothos that I have in my collection at home.
Water Propagation vs Soil Propagation
In my Ficus lyrata post, I talk about why plants don't like standing water and need proper drainage. Plants can be propagated and continue to grow when their root systems are submerged in water because the growth media of plain water is much more simple than soil. The microbiome of soil is very complex, with mineral and organic compounds whose properties change when submerged in water. When propagating in water, if changed out regularly, there is nothing that can cause rot.
Many plants can root very easily in soil, and it can help to avoid having to stress the plant out when it's time to pot the rooted cutting. Sometimes, soil propagation is the way to go, but I usually prefer water propagation for a few reasons. First off, baby plant roots are the cutest, and I like to be able to track the progress of my cuttings by looking at the roots. This way, I can tell if the cutting is failing, and potentially try to save it, or throw it out before it affects any others. Second, I live in a very small apartment without any outdoor space, so pulling out pots and potting soil is not an easy task. It is much easier to clean up spilled water than spilled dirt. And third, back to the tiny apartment thing, I don't have enough flat surfaces to put pots, and water propagation takes up less space. There are benefits and drawbacks to both methods of propagating cuttings, so try out both and see what you like!
How to Take a Cutting
The first step in collecting cuttings is to choose your source plant. Ideally you want a plant that is healthy and has been fully fertilized. This way, the source plant can heal its wounds and use the change in auxin flow to create some new branching. Keep in mind that the way you take cuttings will change the source plant aesthetically. I usually take the longest stems, or anything that looks out of place. It is easiest to take a long section off of the plant and cut it up into multiple cuttings on a flat surface. You can have cuttings with as little as one leaf, or you can root entire shoots if you want more immediate results after potting.
I got a beautiful and healthy long section of pothos from the greenhouse where I work, at Foliage Services here in Portland, and did my best at creating this little video demo of me cutting it up into seperate cuttings. (This is the first time I have tried to do something like this so go easy on me<3)
Propagation Environment - how to keep your cuttings happy and thriving
Propagules are very vulnerable until they have developed root and shoot systems to support themselves. To protect them and promote growth, there are 5 main factors to control: water, light, temperature, gasses, and nutrients
water: the most important to manage for cuttings. goal is to maintain turgor pressure within the cutting aka amount of water inside the cells of the plant. want to minimize water loss through transpiration (the movement of water through a plant), so keep humidity high. When propagating in water you don't need to monitor as much, but when rooting cuttings in soil must mist them to keep humidity high enough, or grow under an enclosure, like a plastic bag.
light and temp: High light intensity and high air temperatures both increase transpiration, which is not a good thing. Also, certain temperatures promote root growth: between 65-80°F. You can use a heated seedling mat under your propagules if you're having trouble rooting certain species.
gasses: As you may remember from my post about on fiddle leaf figs, gasses and gas exchange are necessary at root systems. Oxygen is needed for cell respiration, aka how plant cells make energy from nutrients. If no oxygen is present, the root cells will die.
Water from your tap contains dissolved oxygen (and cold water has more dissolved oxygen than warm!) but as time goes on, that oxygen runs out. This is one of the reasons it's important to change out the water that you propagate in.
nutrients: When your cuttings don't have a root system yet, they cannot take up nutrients, so you want to collect cuttings from healthy, fully fertilized plants if possible. If you are taking cuttings as a last ditch effort to save a plant, don't worry about it, but fertilize it (cautiously and very lightly) once roots are established. Fertilizer won't help form roots, but can help roots grow, so it's not a bad idea to use a water soluble fertilizer after roots have developed if you plan on keeping your plant in water for an extended period of time, which you usually can do if you're intentional about it and replace the water frequently. Just be sure to follow the directions on your fertilizer and avoid burning the roots.
Once You Have Roots - next steps
Rooting cuttings takes patience. So, you might ask, how long do I have to wait before planting? You can keep most cuttings in water for a very long time as long as you change the water out relatively often. I have some plants, like the pothos in my shower, and all of the cuttings from my Tradescantia that I have no room for, that permanently live in water, and I don't plan on moving to soil unless I need to. But, if your water rooted cuttings are not growing anymore, or are showing signs of decline, like browning or slimey roots, it may be time to get them in some soil. And if your goal was always to pot your cuttings and you see roots and just can't wait any longer, go for it! Pot those babies up in some soil.
How to avoid transplant shock
One risk in moving your cuttings from water to soil is sudden decline in a plant due to rapid change in environmental conditions, known as transplant shock. Waiting until your cutting has a more extensive root system is one way you can ease its transition from water to soil. Ideally, you want to see root branching and root hair development before potting. I would also suggest to try to keep some factors the same between where your cutting was, and where your potted plant will be, such as similar light intensities. Keep your potting soil moist after you pot the cuttings - water lightly and regularly, and/or mist them. When you start to see that your cutting has successfully made it to a potted plant, and is putting out new growth, you can get back to a regular watering schedule of once a week or so.
Potting your cuttings
When potting your rooted cuttings, you want to allow room for it to grow so it doesn't have to be repotted again in the near future, but not so much room that the soil never dries out.
I always pot my cuttings into 6 inch pots and put 3 to 6 cuttings in per pot, depending on their size.
This way, right off the bat, the pot looks aesthetically nice and full, and then if a cutting doesn't make it, I don't have an empty pot. Also, make sure you follow general best practices for repotting plants, like allowing for drainage, and not packing the soil too tight. If some of your cuttings don't make the transition from water to soil, don't fret - that happens! Be gentle on your cuttings, but be gentle on yourself too. Part of the beauty of plants lies in their life cycle, and their legacy will live on in their clonal brethren.
Having and caring for houseplants is partially about aesthetics, but also a lot about experimentation and having fun. I hope that you can take some of the information here and use it to try some new things with your plants!
Are there any other questions you have about propagation, in general, or for specific plants? Want to prove that you actually read this whole thing? Leave me a comment down below <3
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