"Cliff's Notes" for Propagation Clinic
I am posting here an essay I wrote for those of you who might have liked to attend my free clinic tomorrow, but already have other plans on your calendar. Feel free to reach out with any questions.
Free Plant Propagation Clinic Grumpy’s Garden Club
May 21st, 2022 written & hosted by Steve Hill
It his book titled, Secrets of Plant Propagation, Lewis Hill wrote, “By planting a seed, rooting a cutting, attaching a graft, and the other myriad of activities of plant propagation...you are involved in the process of creating new life - that awesome natural force that is far beyond man’s understanding.”
Plant propagation is a fascinating sub-category of gardening - like gardening distilled. These advanced gardening practices give us the ability to cultivate the specific plants we love the most and in quantities that are truly exponential if desired.
I will begin this essay with defining my terms and explaining how “propagation” is distinct from both cultivation or germination of plants.
Propagation is simply defined here as the “intentional and controlled reproduction of desirable plants”. If you have divided strawberry root-crowns, dug up “volunteers” in a blackberry patch, or separated crowded aloe vera plants into new pots then you have already engaged in some plant propagation on a small scale. Propagation can be starting plants from seed, or it can be cutting parts off of a plant and suspending them in a humid environment until they produce roots. The idea behind propagation is that we are in charge of the reproduction process. Cultivation is care that promotes the growth of plants & germination is sprouting seeds.
6th grade science may have taught us that plants can reproduce using two different biological processes: Sexual & Asexual reproduction. However, the plants that result from each of these two methods are very different.
With sexual reproduction the genetic material from two different individuals comes together to create a completely new individual. In plants, this happens during pollination of the flower and results in fertile seeds. However, not all plants reproduce best by seed, and the germinated seeds will not result in plants bearing the exact traits of their parents. Occasionally, the offspring possess more desirable traits like the Fuji Apple, or the Hass Avocado. But far more often that is not the case and the offspring will be less desirable than the parent.
Heirloom seeds are types that have been “stabilized” by open-pollination for generations. Each seed is still a unique individual, but the common traits are so homogenized that the variation from one individual to another is very minimal. Heirloom seeds are similar to carefully curated dog breeds with a proven pedigree.
Hybrid seeds are more recently developed varieties that have been carefully cross-bred between two parents having desirable characteristics. The seeds are most often first-generation offspring expected to possess the targeted combination of desirable traits from each parent. Due to genetic drift, the hybrid seeds are only “good” for one generation. If you save the seeds from hybrid fruit - they will not produce that same fruit the next season. If you plant hybrid seeds and really like the characteristics of the plant that grows from them you will need a different method in order to keep those genetics going for future crops. You will need to clone.
Asexual propogation involves isolating a part of the parent plant and using that tissue to generate a copy of the parent. This potentially allows the genetics of the parent to carry on indefinitely in the life of all future clones.
Asexual propagation is accomplished many different ways and each method has it’s strengths and weaknesses. Today, I will explain three different asexual propagation techniques that I use to clone plants.
In this clinic we are only interested in asexual propagation because it is assumed we have “mother” plants with desirable characteristics that we wish to duplicate. In future clinics we hope to discuss the fascinating art of selective breeding whereby new varieties of plants can be developed with unique characteristics all their own.
There are several different methods of Asexual propagation, but today we are going to focus on two of the simplest and most practised methodologies: Layering and Rooted Cuttings. Both of these types can be accomplished using several different techniques. I have experienced good success with what I will share.
Layering:
Layering is a propagation method that takes advantage of a natural feature of many plant species where the tissues will begin to form root cells at the point where they make contact with damp soil. Layering in its most basic form happens all the time unaided by humans where a low hanging branch touches the ground and becomes rooted to that spot. This is one way in which groves of trees or masses of shrubs form in the wild.
This is the simplest way of generating a clone, but it requires having branches long enough to reach the ground and that is often not possible when plants typically grow toward the sun.
Air layering is a variation of common layering in that this technique brings the soil up to the branch. Typically, the technique involves creating a watertight chamber containing moist, soilless media wrapped around a wounded branch. This technique “tricks” the plant into thinking it is touching the ground. The plant responds by generating roots inside the chamber during the growing season. Prior to entering dormancy in the winter, the chamber and a part of the branch are removed from the main plant and potted up - resulting in a new self-supporting plant and a genetic clone. The biggest advantage to this technique is that the rooting takes place while the branch is still attached to the mother plant supported by its existing roots and leaves. There is virtually no stress to the mother plant, nor are the baby roots taxed with supporting leaves. It’s kinda foolproof.
I researched what other gardeners have done and combined several air-layering ideas to create a simple, inexpensive, and highly effective technique for myself. I have experienced success rates of well over 80% every season I have used it - even with plants that are notoriously difficult to clone, like Muscadine vines.
The materials needed for our Air-Layering packets include the following:
Food-grade plastic bags: We buy model “S-5390” from Uline: 6” x 10” - 1,000 bags for $19
Perlite - This volcanic mineral can be purchased from any garden center in various quantities.
Peat Moss or Coconut Coir - it does not matter which material you use.
A Clean, Sharp Knife or pruning shears
Duct Tape
String or Bailing Wire about 18” long
The Air Layering Process:
It is most effective to begin air Layering in the Spring so the branches have maximal time to produce new roots before the winter sets in. Some plants like evergreens cannot be successfully air layered at any other time.
Prepare your soil-less medium by mixing 50% dry perlite with 50% dry peat moss (or coconut coir) into a container until thoroughly mixed and there are no lumps or chunks.
Add water to the mixture to dampen it and let it rest for several minutes so that the water can soak into the material. Mix the material as you add water so that all parts receive moisture.
This may take several attempts to get the right level of moisture.
You do not want the material to be soggy and heavy. You want the material to be thoroughly damp or moist, but not so wet that you can easily wring out water by squeezing it in your hand.
There is no substitute for patience in this process. Peat moss or coconut coir can absorb a great deal of water, but it happens so very s-l-o-w-l-y. Rushing the absorption will result in dry spots or a medium that is too wet and leads to problems with rot or root failure.
While the soilless media is resting, prepare your plastic bags by inserting a knife or scissors into the bag along the seams about halfway down the length of the bag and cutting the seam open from the midpoint to the top. When you have slit the plastic halfway down both seams you should end up with a bag that can now only be half-filled and has two long flaps at the opening.
Place about 1.5 - 2 cups of moistened, soilless mixture in each prepared bag and fill it gently so that it is not too dense.
Choose a 1 or 2 year old stem that is straight, healthy, and vigorous. Trim off the leaves and side shoots from a section of the stem that is between 8” and 12” long.
At the middle of this trimmed section use the edge of a sharp, clean knife or shears and scrape away just the outer layer of bark until you can see the lighter wood of the cambium layer. Do not scrape the bark off of the full circumference. Just a small section of damage will be enough to expose the cambium to produce a callus where roots will form.
While it is not necessary, some gardeners will dip or coat the damaged tissue in Rooting hormone. We have had much success without that extra step and expense. However, you may wish to do it if it will help ensure that your efforts are successful.
Tear off a piece of duct tape about 10” long and have it ready in a handy spot. You will need to have it close so that you can reach it and apply it with only one hand free.
Bend the stem enough that it can be inserted into the bag and the damaged bark can make good contact with the media. I push the branch into the mix so that it ends up at the middle of the mixture.
Wrap the loose plastic flaps tightly around the stem and pull them over the bag - wrapping them around the media package. Place the duct tape around the wrapped bags tightly so that air and water can not easily get into the moist media. This takes practice, but once you understand the concept you will be able to adapt it to any plant and find your own way to succeed. Plan on making more than you need.
Finally, tie the string or bailing wire around the middle bulk of the bag and the stem in such a way to support the weight of the package without straining the point where the branch is still attached to the mother plant. This is done to keep the weight from breaking the branch off in high winds. That kind of damage has caused failures for me in the past.
Check on the air-layering package at least every few weeks to make sure it is not taking on too much rain water, or drying out too quickly. Otherwise, you can leave these packets alone until late Fall.
Prior to the first expected hard freeze of the winter season you need to cut the branch free from the mother plant and trim the leafy branch tip coming out of the bag so that only three or four total leaves remain. This helps to balance the quantity of new roots to the leaves they must support.
Pot up your new plant in an appropriately-sized pot using high-quality potting soil & protect from freezing that first winter. I keep my clones outside and on the ground against the South side of a building where they can receive rainwater. I do not supplement their water at all until Spring.
Do not fertilize the new clones until April 1st and do not let them produce fruit the first season for best vigor.
I have found that the best time to establish air layers in North East Texas (Zone 8a) is between June 1st and August 1st. It is difficult to find stems vigorous enough to support the media packages prior to June 1 and air layers started after August 1st do not typically have enough time to form strong enough roots before the first frost. So, we typically mark the calendar so that we always know the period from June 1 to August 1 is when we will be setting up air layers in the vineyard or nursery.
This becomes part of an annual garden rhythm.
Some other helpful tips concerning air layering include:
Be mindful of sun exposure on the surface of the bags. Plastic does not stand up well to UV light and solar heat gain can be a root killer. Try to place your air layers where they will be protected from direct afternoon sun if possible. If that is not possible, consider painting the bag with white latex paint.
If you notice that the media has dried out in one of your bags, there is nothing wrong with adding water to it using a turkey baster. Try to find out why the moisture is escaping and correct that with duct tape.
Each air layer package will have two points where the stem penetrates the bag as it passes through. Make sure when you remove the package from the mother plant that you cut the stem at the right place. You want to disconnect it from the mother. Don’t accidentally decapitate your new plant.
Failing to trim the tip of the new stem is not the end of the world, but it will stress the new roots next spring when the plant comes out of dormancy. You only need to keep two or three nodes, I promise.
It is crucial that you understand the balance between the visible portions of a plant and the invisible roots that support it. You gain nothing by trying to keep a lot of leafy top growth if there is not enough root structure to supply those leaves with water and minerals. This is a common mistake!
Water the plant as soon as it is potted up to make sure there are no air gaps in the soil, however, watering throughout the winter months is usually not necessary. Inspect new plants often to be sure.
Do not fertilize until the Spring. You want the plant to remain dormant so that it can build core roots.
If you have a permanent location in mind for the new clones there is no need to pot them up first.
Pros & Cons of Air Layering for Plant Propagation:
PROS:
The process does virtually no harm to the mother plant.
The mother plant provides all the support the baby plant needs as roots develop.
Watering the media is usually not required. This is typically a very trouble free system.
Very high success rate (>80%) with low cost in materials and work.
CONS:
The process requires at least 8 weeks for viability of the clone, sometimes longer.
The work must happen out in the field at the location of the Mother plant.
Difficult to produce large quantities of clones without access to many identical mother plants.
Clones must be protected from extreme temperatures because they are not connected to earth.
Pros & Cons of Common Layering for Plant Propagation:
PROS:
Usually no cost involved at all.
Does not require protection from extreme temperatures because the earth is a heat sink.
This is very easy to do.
CONS:
Requires a branch long enough to reach the ground - not every plant is a suitable candidate.
The new clone becomes a transplant that requires digging up to pot or relocate. This damages roots and should not be attempted between April & October.
This is a slow process with no easy way to verify that the plant is rooting well.
It is even easier to watch Youtube in the air conditioning & buy plants grown by somebody else.
Rooted Cuttings:
Probably the most common propagation technique used by gardeners for the last 1,000 years is the process of rooting plant cuttings. This process involves cutting off a specific portion of the mother plant and suspending it in conditions that are conducive to generating new roots. This can be tricky, because once a portion of the stem is cut free from the mother plant it immediately begins to dry out and die from the bottom up.
Plant cells located in the stem at the nodes where new leaves form and at the cambium layer just under the bark surface are very similar to “stem” cells in animals. These cells are programmed to respond to certain stimuli in their environment and can produce various different tissue types as the needs of the plant change.
Damaged cells at the cut will try to repair themselves by producing what is called a callus. This callus is a lumpy formation of white-colored tissue that will eventually form new roots to help the plant find and gather water and nutrients to survive.
The needs of a recent cutting are identical to that of the mother plant:
The cells need a “Goldilocks” supply of clean water - not too much - but not too little.
This water mostly moves in one direction: from the roots toward the leaves.
The cells need minerals and nutrients from the soil to survive and make new cells (grow).
The cells need energy (sugar) that is generated in the leaves as a reaction to sunlight.
The cells control their temperature by opening and closing stomata, which are little vents in the leaves where the release of water vapor is used in a fashion similar to perspiration in humans.
However, once cut, the tissue is no longer connected to the water or mineral source. This must be addressed immediately for the cutting to survive. So, all but a minimum of leaf surface is removed from each cutting to minimize the amount of water lost to the atmosphere through the stomata in the leaves.
In order to keep the cutting alive we need to create & maintain the following conditions carefully.
You will need a sterile media in which to suspend the cuttings so that they will generate roots. The word “Sterile” here means that the media does not contain minerals or food to the cutting.
The media must stay moist but not overly wet or saturated (I will discuss exceptions later),
The media must drain well so that oxygen is drawn into it to prevent diseases. Oxygen is important.
The media should stay cool and not get overheated (anything above 95 F is probably too hot).
The media should never be cold unless the cuttings are being stored for the winter, temperatures below 60 F can actually stop new growth.
The cuttings should be placed so they have indirect sunlight, but never direct sunlight because that can stimulate leaves & outpace the forming roots, it can overheat them, or it will dry out the cuttings.
The cuttings will require regular watering so that they never dry out.
Drying out = death, and it happens exceedingly fast (it seriously only takes minutes).
Warm and Humid environments grow roots…and fungus, and mold, and algae, and bugs. The cuttings must be protected from all disease and pests in order to thrive. It’s not easy.
Ok, so just how do we create an environment that can satisfy all of these picky requirements?
One of our most basic and successful methods has been to create a humidity chamber for the cuttings.This chamber is actually just a mini-greenhouse and it can be easily manipulated to control all of the parameters listed above.
My Humidity Dome Experimentation: (yup, Story time)
The first year I attempted to create a humidity dome was not very successful. I used a black utility mixing tub from a home improvement store and added a few drainage holes. I placed pure perlite in the bottom of the tub, stuck muscadine and grapevine cuttings and watered them in. I built the “dome” out of scrap wood and wrapped it with sheet plastic. Every couple of days I would remove the frame and spray the cuttings with water. Slowly, over the next several weeks, half the cuttings wilted or rotted, and the other half developed new leaves. Out of 100 cuttings I started with, I was only able to produce about 10 viable grapevine plants and zero muscadines. I was amazed that it worked at all, but it did - 10 new clones!
I learned three very valuable things from that failure experiment:
Some plants (like muscadines & S. magnolias) do not root well from cuttings, and they just won’t.
Air circulation is very important or fungus will take over. Fungus OWNS East Texas, and…
100% perlite as a propagation medium has limitations because it does not hold enough water.
The following year I acquired (stole) a dozen blue buckets that were originally used to contain mineral licks for cattle. They each had a capacity of about 15-20 gallons and were UV stabilized to handle the direct sun out in a pasture. My idea was to drill drainage holes in the bottom, fill them ⅔ full with a 50/50 perlite & peat moss soilless mixture, and then start grapevine cuttings in them.
I prepared the cuttings, moistened the media, and stuck the cuttings into the mix. When I had everything in place I tied a piece of white sheet plastic to the top of each bucket and then poked a couple of small holes to allow hot air to escape. The white plastic was opaque, but it would still allow some diffused sunlight through.
These buckets sat outside from April until July when the top growth became too large to contain under the plastic. I noticed that everywhere the leaves touched the plastic they would rot. I could not leave them uncovered as they were, so I then chose to pot them up at the worst time of year for transplanting, Summer.
I moved the heavy pots onto my work bench and tried to extract the plants. Their roots were so intertwined that there was no way to pull them out without damaging half of the roots. I tried turning the buckets over and dumping the contents on the workbench, but that just crushed & broke off the new leaves and branches under the weight of the root ball.
Finally, I decided to use my garden hose to wash the soil-less media away from the roots and untangle each plant as carefully as I could. This actually worked fairly well. I probably used 1,500 gallons of water and made an awful mess of the yard, but I managed to salvage about 25 Herbemont, 30 Lenoir, and 20 Blanc du Bois grapevines with another handful of others. I had successfully cloned over 100 plants that way and got a taste of real success. Most of those plants survived being transplanted into pots and all the lessons I still had to learn about shading young, potted plants from the over-zealous Texas sun.
My next experiment was more involved. (I no longer use unwieldy containers and sheet plastic to make humidity domes.) The method I adopted next for large scale production was automated and involved large raised beds filled with course construction sand as the media. The watering is handled by intermittent mist on an expensive timer that sprays water for 10 seconds every 10 minutes during daylight hours. This mist kept the tops moist and cool but not overly wet. The entire system was shaded under wooden structures I built & covered with 80% sunshade cloth. These were designed to allow direct morning sun from dawn to about 11:30am and then only indirect sunlight until sunset. This system is effective, it is scalable, and it allows me to make up to 27,000 rooted cuttings a year in a space smaller than a 2-car garage. Meditate on that a second.
The intermittent misting system has HUGE potential, but it also has some downsides. Plant losses were staggering the first two seasons due to the open sides and the drying out of cuttings when the wind would blow harder than the misters. The cuttings were subject to critters that loved their brand new leaves and fresh, juicy roots. The tight quarters allowed disease to spread quickly and it had to be controlled chemically. Overall, it’s a pretty cool system, but probably better suited for cooler and drier climates than ours. I’m still tinkering with it, but I have found something I like even better! Keep reading and I’ll explain.
Plant propagation does not require a greenhouse nor must you have an elaborate watering system to provide all the requirements of your cuttings. All you really need is understanding of how the plant works, and then apply a bit of your own creativity. It’s your garden; you should cultivate it in your own unique way!
Types of “Cuttings”
Every plant will have a time period in which it responds best to propagation. There is not room in this article to list all the plants and their preferred method, but that information can easily be found with a quick internet search or a good book on plant propagation, like the one I mentioned earlier written by Lewis Hill. A little bit of research will help you save a lot of personal time and effort so I encourage you to do the necessary homework to manage your outcomes.
The cutting process (like most gardening) depends on timing. There are three general periods in which to start new cuttings and this timing has everything to do with the maturity of the plant you want to clone.
Softwood or “Greenwood” cuttings are taken starting in mid-Spring and lasting until mid-summer. These cuttings are taken from the supple, green tips of the current season's growth when the stem or branch is still pretty young and can be broken easily if bent. The leaves will be immature and not yet hardened off by the sun. Immature leaves are usually recognizable by smaller size, having a more yellow than green color, and/or a different sheen or shine on the surface of the leaf. Some plants respond best as softwood cuttings.
Semi-hardwood cuttings are the current season’s growth, but they have matured some and are not as supple or easily broken when bent. A semi-hardwood cutting will have mature leaves and it will bend without snapping. The bark will begin to look more mature but it will not be hard and brittle, nor will it be thick like the older growth from prior seasons. Semi-hardwood cuttings are usually taken from June-October in our area of North East Texas (Zone 8a). The majority of plants will respond as semi-hardwood cuttings.
Hardwood cuttings are taken from the last season’s wood that is at least one year old and only after the plant has gone dormant for the winter. These cuttings are larger and the wood is fully mature and rigid. It will not bend without some damage and there are no leaves left on it. Hardwood cuttings are taken from November through the end of January in our area. It is important not to take them so late in the winter that they do not have time to produce roots before the weather gets hot again. Root production typically takes at least 6-8 weeks so mark your calendars and count backwards to identify your best window of opportunity..
When you have selected a plant to clone and are ready to start the process of making the cuttings, this activity is called “striking”. You “strike” the cuttings by removing them from the mother plant, trimming off the appropriate amount of leafy growth, and often prepping the bottom end with a rooting hormone treatment. This process is not difficult to learn, but it can be more of an art than science. I find the nature of the work and the hands-on rhythm to be both enjoyable and therapeutic. It is a peaceful task best set to your favorite music.
Before I share my current and most favorite propagation technique I will explain a tried-and-true rooted cutting method that has been successful for me and popular with expert gardeners since at least the 1800’s.
The Cloche: A beautiful little tool for creating a suitable environment for new life.
The Cloche is a bell shaped, transparent structure that is used to cover plants in order to protect them and provide optimal growing conditions in a very small space. They were originally used in Europe in the 19th century and made of glass. In modern times we commonly mimic the cloche concept, with sheet plastic, hoop houses, greenhouses, and clear tray covers set on seed flats.
A “redneck cloche” can be made of a used, plastic, gallon milk jug by cutting out the bottom of the jug along three sides, folding the bottom outward, and placing the hollow opening over a baby plant. The left-over plastic flap can be weighed down with a stone or brick to hold everything in place. The lid of the jug can be used as a vent by removing it on hotter days, or closing it up to retain moisture. This trick has been around for decades in rural gardens to get tomatoes & peppers started earlier in the season or protect them from sudden cold snaps & bugs while they are young. A cloche is not a long term garden feature however. They will need to be removed when plants get big enough to touch the sides or if the weather is consistently above 80 F.
In East Texas, cloches work best indoors where the temperature never gets above 80 F and there is a ready source of clean water. You will need to put your eyes on the cuttings daily. Closed, humid environments are perfect for growing fungus, so it is important to let your plant “breathe” by removing the dome and airing it out for a couple of minutes everyday. It is also important that you keep the media moist - but never soggy. Roots NEED water to live…but they HATE being waterlogged. Check your moisture daily, only add enough clean tap water to remain moist. Keep a look-out for fuzz, spots, or anything off-color. It’s a fine line between rooting and dying.
Today, I will explain how to make an effective cloche using a plastic drinking bottle and a commonly found seedling pot. Gardeners are always experimenting & we often recycle items to make work easier (cheaper).
You will need the following items to do this at home:
50/50 mix of perlite and peat moss (or coconut coir) pre-moistened but not soggy.
A clear plastic drinking bottle. A 2 liter bottle works perfectly with a 1 gallon trade nursery pot and 1 liter bottles work well with 1 quart pots like Bonnie’s 3-4” round veggie pots.
Rooting Hormone (powdered or liquid) - I prefer “Dip-n-Grow” because the pros say it works.
A dibble. This can be a large nail, a pencil, even a small stick that can make a hole in the mix.
A sharp, clean, knife or pruning shears. (Always clean with isopropyl alcohol prior to use)
Duct tape
The process of rooting cuttings with a cloche:
Find a clear plastic drinking bottle that has a diameter similar to your nursery pot such that the bottle fits inside of the top rim of the pot. This is important. Keep the lid but remove the label on the bottle. I prefer using “DejaBlue” 1 liter bottles because: cheap, the right size, and the bottle has smooth sides.
Using your knife or a pair of kitchen scissors, cut the bottom of the plastic bottle off in a straight clean line. You want to leave as much of the sides and length of the bottle as you can. Do not discard the lid. This is your new cloche. It will create the clear dome that contains the humidity near the cutting.
Clean the shears, pot, & bottle with isopropyl alcohol to prevent contamination. You can skip this step at your own risk.
Prepare your sterile, soilless mixture in exactly the same manner as you would for air-layering.
Gently pack the moistened soil-less mix into a clean pot and cover with the new cloche.
“Strike” your Cuttings:
Identify a healthy, mature branch on the mother plant and cut the tip off about 4”- 6” long using your clean knife or pruning shears. This cutting should be taken from the young wood on the plant.
Remove the leaves from the bottom 2/3rds of the new cutting leaving at least a couple leaves at the tip. It is very important to always know what is the top and what is the bottom of the cutting. The end closest to the trunk is always considered the “bottom”.
Time your work so the cuttings are never allowed to dry out. If your plan is to take many cuttings at a time then be sure to have a jar of clean water close by so that you can place each cutting in the water bottom side down as you cut them. Try not to let the leaves at the tip remain submerged for long. Treat these cuttings like flowers in a vase and work as quickly as possible.
“Sticking” your Cuttings:
Using your dibble, place a hole in the moist media that is about as long as the stripped portion of the cutting. This hole will prepare a path for the cutting so that it does not bend or break during insertion and the rooting hormone is disturbed as little as possible.
Dip the stripped cutting in a rooting hormone and then immediately insert the cutting into the prepared hole in the moist medium. This action is referred to as “sticking” a cutting. Immediately firm the medium by pressing it down and toward the cutting you just stuck.
Water the cutting well with clean water within a few minutes of “sticking”. Do not wait long.
Cover the cutting with the cloche and be sure to close the top of the bottle with the cap.
Using a couple of small pieces of duct tape, fasten the cloche to the pot so that it will not get easily knocked or blown off. The juncture between the cloche and the pot does not have to be sealed tightly.
Place the cutting in a lightly shaded spot that will never receive direct sunlight. A bright window indoors will work as will a well shaded spot in your yard or garden. Direct sun will hurt a new cutting.
Watch the cuttings carefully over the next two weeks for signs of increased growth or distress. If you notice any fungal growth then remove the cloche and treat the cutting as you would a house plant; watering only as needed. As a precaution, an antifungal spray can be used at each watering to help stop the spread of fungal disease.
When you recognize the growth of new leaves, remove the cap at the top of the bottle, but keep it for future use. Remove the cloche a few minutes each day to let it air out, water the cutting if needed, and then reattach the cloche without the cap on.
After six weeks the chances are good that your new cutting has enough roots to be transplanted into a larger pot using a general purpose potting soil and kept in indirect sun outdoors. Gently tug on the cutting and if it resists coming up then it probably has enough new roots to survive.
Once the cutting has roots over 2” long then it can be transplanted into soil. Trim the plant by cutting off the tallest tip of new growth and transfer it to a slightly larger pot filled with quality potting soil. Apply a small amount of timed-release fertilizer such as Osmocote granules and water regularly for the first season. Touch the soil often, and only water when the top ½” becomes dry.
Most professional nurseries will use a 40-50% shade cloth to protect their new potted plants from sun scorch. Plastic pots are made out of black plastic because it has the most UV protection, but black is also the worst color for absorbing radiant heat from the sun. The rootzone can be quickly killed if the sun is not managed.
Even mature plants in pots will benefit from some relief from our Texas Sun, especially after 1pm.
Tips for a better understanding of Rooted Cuttings and how asexual propagation works:
There are two portions of a plant that must be managed. The visible portion and the invisible root zone. Each of these portions has different needs that can affect your success and those needs are met in different ways.
The humidity dome created by our cloche (or a greenhouse) is mainly used to protect and provide for the needs of the visible parts of the plant - namely the stems and leaves. This is the part of the plant that generates the energy for the plant, but it is also where the plants lose their moisture to the atmosphere as they regulate their temperature.
The propagation media protects and provides for the needs of the root zone. A good propagation media will retain very high humidity, but will not allow water to sit directly against the roots or the stem of the plant for very long. If the roots are in direct contact with water then the oxygen content of the water must be kept near the saturation point at all times.
To manage the moisture effectively the propagation media must also drain very well. This uses the action of the receding water to pull oxygen down into the root zone as it fills the voids left by the water. Oxygen will minimize diseases.
The propagation mix must be sterile (not sanitary).
The word sterile in this context does not mean “clean” as much as it means the mix has little to no nutritional value. The reason we do not want nutrition at the rooting stage is because nutrition can be used by harmful organisms to help them grow and cause rot. More importantly, if the plant is lacking nutrition - the natural urge is to produce new roots to go find some. We want roots.
Grumpy’s current propagation method: Deep-water Hydroponic Rooting Tanks:
Remember, once cut, the future plant has no means for collecting water, maintaining leaf temperature, or supporting new growth. But there is still enough stored energy in the cells of the stem to generate new roots if we can keep them alive long enough. Hydroponic cloning satisfies all of these conditions with significantly less effort than a cloche. I have built hydroponic cloning tanks using off-the-shelf products you can modify yourself and they work quite well. These allow me to create cuttings almost year-round while I am at work elsewhere.
The success rate of hydroponic cloning may not be as high as air-layering, but it is not labor intensive, it can be repeated easily many hundreds of times, and it produces roots dramatically faster than most other methods.
You will need the following tools & materials to build a hydroponic rooting tank like I use:
Sturdy, opaque, plastic storage container with lid. My preferred container is the Project Source brand “Commander” in 5-gallon size with a yellow lid. Lowes Item #1021708, for $9.98 each + tax. A similar 7 gallon container is available from Home Depot for $6.98: Model #206152, Store SKU #1003230599
A ruler or measuring tape & pencil.
A power drill & 1” hole-saw bit. I prefer forstner bits over paddle bits, but ultimately all you really need is a way to make a clean hole in the plastic lid, 1” in diameter, about 35 times.
An aquarium pump. It needs to be large enough to serve a 5-10 gallon aquarium.
An air stone diffuser. These come in all shapes and sizes. You want a stone that does not float.
¼” plastic air tubing and in-line valve compatible with your pump and air stone.
Suspension sponges. You can buy hydroponic sponges on Amazon made specifically for this purpose, but they are expensive and unnecessary. My favorite method is cutting strips out of foam sill-sealer I found at the hardware store on the insulation aisle. However, all you need here is a material that can get wet and stay wet without damage, is soft, & will hold cuttings upright. I will explain further.
Pruning shears or strong kitchen scissors.
A mischievous gleam in your eye. (Not essential for success, but it seems to help with my experiments)
Fabrication:
Mark the center of each raised square on the yellow lid.
Drill 1” holes in the center of each square as marked. Be careful not to go too fast or break the plastic.
Use shears to cut a notch into the lip of the container for the air tubing. This will allow you to remove the lid without disturbing the air tubing.
Cut a short piece of tubing with the shears between 6-12” long and attach it to the output on the air pump.
Connect the valve into the other end of the tubing on the air pump.
Connect the remainder of the tubing to the other end of the valve and insert the air stone on the very end of that tube.
Place the container on a sturdy surface like a counter or table top where it will not be in the way of other activities. Access to indirect sunlight is best but not absolutely necessary. Never direct/unfiltered sun.
Fill the container with tap water to a point between 1 & 1.5” inches from the top.
Place the air stone into the water and let it sit overnight before you plug in the pump.
The tank is now ready to be used for your first “Cycle” of clones.
Tips for best use of the hydroponic rooting tank:
Strike your cuttings as you normally would for other propagation methods. Rooting hormones will NOT be a benefit with hydroponics so do not bother. It can taint the water and cause other problems later.
Wrap your fresh cuttings in prepared sponges or in strips of foam like I do. Use enough material so that you must squeeze the sponge/foam slightly to insert it into the drilled holes. This friction will keep your cuttings suspended in the water without letting them fall in.
I often wrap several cuttings of the same variety together and insert them into a single hole. This allows me to multiply my success and get far more than 35 plants into a 5 gallon tank.
I prefer to take enough cuttings to fill every hole on the same day. I write the date on something and place it on the lid to remind me. Once the lid is full of cuttings you have officially started your first hydroponic propagation cycle. Each cycle lasts about 3-4 weeks depending on your environment.
You do NOT need any fertilizer or hydroponic solutions. Remember, you want the media to be sterile and tap water is sterile enough (by our definition anyway).
Check your water level and condition weekly. Eventually the water will evaporate enough that you may need to add some so that the ends of the cutting stay submerged. I have lost hundreds of successfully rooted cuttings by forgetting to check the water level. Please learn from my mistakes!
Also, water is the “stuff of life” so it will need to be checked for algae. If the water is starting to look a little green then it should be replaced. I keep additional containers handy for this purpose. Simply remove the lid with the cuttings still in it. Place that lid on a second container while you dump out the old water. Rinse the container and wipe the sides with a cloth to remove any algae build up. Replace with fresh water to within 1.5” from the top and replace the lid on the tank. This should ideally be done once a week but I have gone as long as three weeks without changing the water & had no problems.
For many plants you will begin to see roots developing within the first 4-5 days. When the roots have gotten 2” long or have begun to start developing root hairs you can experiment with potting those plants up. It is not uncommon for cuttings to develop robust roots at least 6-8” long in just 3-4 weeks. These should be potted up at your earliest opportunity.
Leaving the cuttings in the sterile water too long can starve them of nutrients & it can allow root rot to set in. Always remember to check on your cuttings at least weekly. They need you sometimes.
Have some pots and potting soil ready and nearby so that you can pot up rooted cuttings as soon as they are ready to go. These new plants will need to be hardened off before they can live outside.
If you time it correctly you can get 8-10 cycles of cuttings rooted during a normal growing season. With only one hydroponic rooting tank, and only one cutting per hole, that is a potential for between 280 & 350 new plants per year. This rapid multiplication is exactly why I have no fewer than 15 of these tanks in my greenhouse filled with no less than 3 cuttings per hole at any given time. My current setup has the potential for 12,600 new plants a season. It only takes up 26 square feet of bench space. I have plans to expand further.
The optimal season for hydroponic rooting aligns with the natural growing season; March - October.
Many plants will not respond well to rooting attempts during winter months. (They know somehow.)
Remember that your newly potted cuttings are fragile for the first few weeks in the pot. Keep a close eye on them and do not place them in direct sunlight until they have been potted for at least 1 month and have learned how to sip water from soil.
Potted plants will inevitably require more water and fertilizer than plants that have been planted out in God’s earth with easy access to moisture and organic nutrients. If it will be a while before your potted plants can find their way to a permanent earthen home in the ground then it may be a good idea to plant them out in the garden temporarily and transplant them to their final location during the next dormant season. The heat stress is terrible in a pot and that is hard to over-emphasize in Texas. I have used an infrared thermometer to measure temperatures of 137 F on the side of black pots in my own nursery. It is no wonder some potted plants fade so quickly in July.
We fertilize our plants on a regular schedule three times a year. We apply fertilizer on April 1st, May 1st, and June 1st. We do not typically apply any other fertilizers for the remainder of the growing season. In our area it can be harmful to many plants to fertilize after July due to the fact that the heat can scorch the new growth and if the plant is still producing new green leaves in the fall they will be more susceptible to frost damage.
I recognize only two seasons: “Actively Growing Season” from late February to Mid-October & the “Dormant Season” from first freeze to bud-break. It’s a good problem to have - but it has to be managed a little differently than those well-meaning folks writing about plants for Vermont or New Hampshire in Better Homes & Gardens.
If you found this information helpful - then please tell your friends about Grumpy’s Garden Club!
Let them know that we offer free clinics like this one throughout the growing season and all our future events can be found on our website at: www.grumpysgardenclub.com
If you like, send us an email and let us know what you thought about it, what you enjoyed the most, or what you thought could be improved upon.
Our email address is: grumpysgardenclub@gmail.com
Your participation and input is one of the most valuable gifts you could give to us!
Below is the printable PDF version:
Propagation Clinic - May 21, 2022
.pdf
Download PDF • 886KB