A cutting, or clone, is a short piece of stem cut from a mother plant and rooted so it grows on its own. A mother plant is a cannabis plant kept under 18 hours of light a day, so it stays vegetative and never flowers. Every rooted cutting has exactly the same genes as its mother. This is how growers repeat one selected plant across a whole crop.
This part explains why cuttings can grow roots, how to take them, what conditions they need and how rooting hormones work. It then covers water cloning, air layering, aeroponic cloners and willow water. It ends with a troubleshooting table and a sample schedule.
Translator’s note: This article covers growing technique only. In Thailand, cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568, in force since 26 June 2025. Check what your licence covers in Licensing and Compliance in Thailand.
This is Part 2. Part 1: Mother Plants & Cloning: Your Genetic Vault — From Selection to Infinite Reproduction
Why a cutting can grow roots
If you know how a cutting stays alive, it is easier to find the cause when one dies.
Water moves up the plant through the xylem, tubes of dead cells that run from the roots to the leaves. Sugars made in the leaves move down through the phloem, living cells that carry energy to the roots. Water evaporates from the leaves, which is called transpiration, and this pulls more water up the xylem.
A fresh cutting keeps losing water through its leaves, but it has no roots to replace that water. This is why you cut back its leaves. Leave enough leaf for some photosynthesis, but not so much that the cutting dries out.
Auxin is a natural plant hormone that starts root growth. Lower branches contain more of it, so they root more easily than upper ones. Adding a rooting hormone speeds things up a lot. Without one, a cutting can take a month or more to root. With a product such as Clonex gel (3,000 ppm IBA, or indole-3-butyric acid), roots form much faster.
What to do: Take most of your cuttings from the lower branches, and trim each cutting’s leaves before you put it in the growing medium.
Rooting hormones: gel, powder, quick dip and soak
IBA is the auxin in most rooting products. Strength is given in ppm (parts per million) or in percent: 1,000 ppm is 0.1%. Products for soft cuttings such as cannabis use roughly 500 to 1,500 ppm or more. Clonex is at the high end, at 3,000 ppm.
NAA (1-naphthaleneacetic acid) is a man-made auxin that is also used in rooting products, sometimes mixed with IBA.
Rooting products are used in four main ways:
- Gel coats the base of the stem and stays in place.
- Powder sticks to the wet stem. See step 5 below for how to handle it.
- Quick dip: the base of the stem goes into a stronger liquid for a few seconds, usually 1–5.
- Soak: the base of the stem stands in a much weaker liquid for several hours.
Use the strength printed on the label and do not make it stronger.
Translator’s note: Garden shops in Thailand sell rooting products made for propagating fruit trees and ornamental plants. Check the label for the active ingredient (IBA, NAA or both) and its strength. To convert percent to ppm, remember that 0.1% = 1,000 ppm. For Clonex, ask local shops whether it is sold here.
What to do: On each tray label, write the product name, its active ingredient and its ppm, then record how many cuttings rooted. After two or three batches you will know which product works in your room.
Taking cuttings step by step
The ideal cutting:
- Comes from a plump lower branch, where there is more natural auxin
- Is not too old or woody
- Has at least 2 nodes, the points where leaves and side buds grow from the stem
- Has young leaves 3–4 cm or larger
- Is no longer than 10 cm in total
Process:
- Cut at a 45-degree angle close to a node, using a sterilised razor blade or scalpel. A sterile blade keeps disease out of the fresh wound.
- Put the cutting straight into a glass of water. This stops air getting into the xylem. An air bubble there, called an embolism, blocks the water supply and kills the cutting.
- Remove the lower leaves, keeping only 1–2 young leaves at the top. This reduces water loss.
- Apply rooting hormone. Coat the bottom 2–3 cm of the stem with Clonex gel or a similar product.
- If you use rooting powder, re-cut the stem just below the powdered part before you insert it. Too much powder can block water uptake.
- Insert the cutting into a medium you have already wetted: rockwool cubes, jiffy pellets (compressed peat discs that swell in water) or a light soil mix. Wetting it first means the stem has water from the start.
- Cover with a humidity dome, a clear plastic lid over the tray, and mist the inside of the lid. This keeps the air around the leaves humid while there are no roots.
According to the original, rockwool cubes, an IBA rooting gel and a propagator dome together give a high success rate. This holds for home growers and commercial farms alike.
Translator’s note: Take cuttings in an air-conditioned room or in the cool early morning, and keep the cuttings out of the sun. Cuttings lose water fastest in heat.
What to do: Before the first cut, lay out the blade, a glass of water, the gel, the wet cubes and the dome. Then each cutting reaches water within seconds.
Conditions for rooting
| Factor | Target range | Best |
|---|---|---|
| Temperature | 18–25 °C (64–77 °F) | 22–23 °C (72–73 °F) |
| Humidity | 70–90% | About 90% at first, then lower it step by step |
| Light | Low intensity, fluorescent or LED | Lamp about 20 cm above the cuttings |
| Day length | At least 10 hours | 18 hours preferred |
Keeping the temperature steady matters more than hitting an exact number. Swings stress cuttings and slow root growth, so keep the rooting area stable.
Start with humidity high, around 90%, and lower it gradually as roots form. This pushes the cutting to stop relying on moisture through its leaves and start drawing water through its new roots.
Translator’s note: Thai rooms often sit at 30–35 °C, well above the 25 °C top of this range. A closed dome in a warm room gets hotter still, especially near a window. The practical answer is to root cuttings in an air-conditioned room under low-heat LED or fluorescent light. In the rainy season, open the dome vents once a day so the constantly wet air does not rot the stems. See root rot. The air conditioner stops during a power cut, so check the temperature inside the dome when the power comes back.
What to do: Put a min–max thermometer inside the dome and write down the readings every day. If cuttings fail, you can then see whether heat caused it.
Other ways to root cuttings
Water cloning: the simplest method
Put the cutting straight into a glass of water. You need no rooting hormone, no dome and no special medium.
- Choose lower branches, which have more natural auxin.
- Cut at 45 degrees, close to a node.
- Keep the water at about 21 °C.
- Change the water daily if you can.
- Place the glass under fluorescent light or near a bright window.
- The first white root bumps appear around day 12.
- Cuttings can stay alive in water for 2 months or more.
It is slower, but it costs almost nothing and needs no equipment. It suits beginners, and it works as a backup when your supplies run out.
Translator’s note: Water is hard to keep at 21 °C in Thailand without air conditioning. Warm water holds less oxygen, and stems rot faster in it. That makes changing the water every day even more important here. Put the glass in bright shade, not direct sun, because sun heats the water.
What to do: Root 5 cuttings in water and 5 with your usual method, side by side. Count the roots on day 12 and again on day 21 to see whether water cloning works in your room.
Air layering: the highest success rate
Air layering roots a branch while it is still attached to the mother. The branch keeps getting full water and nutrients from her the whole time it roots. That is why it almost never fails. The original calls the success rate effectively 100%. Read that as “very high”, not guaranteed.
Procedure:
- Choose a healthy branch on the mother.
- Scrape 5–6 cm of bark off the branch where you want the roots.
- Apply rooting hormone to the bare area.
- Wrap it in moist rockwool or sphagnum moss.
- Seal it with aluminium foil or plastic wrap so it stays moist.
- Roots form in about 15 days, while the branch keeps growing normally.
- Once you can see roots, cut below the rooted part and plant it in a pot.
Advantages:
- No transplant stress, because the roots form before you separate the branch
- Almost every layer roots
- Needs no extra rooting space
- Roots form faster than with most other methods
- Gives larger, better-established clones from the start
Translator’s note: This is the same method many farmers in Thailand and Vietnam use to propagate fruit trees such as longan and lychee. If sphagnum moss is hard to find, moist coco coir is a common substitute. Check the wrap every few days, because a layer can fail if the moss dries out.
What to do: Start one air layer on a strong lower branch at your next cutting session. Compare its roots with your dome cuttings after 15 days.
Aeroponic cloners
An aeroponic cloner holds cuttings in soft foam collars above a closed water tank. A small pump sprays a fine mist onto the bare stems, so no growing medium is needed. The stems sit in moist air with plenty of oxygen, which helps roots form.
The same warm, wet tank is also good for disease. Keep it clean:
- Empty, wash and disinfect the tank, sprayers and collars between batches. A problem from one batch then cannot pass to the next.
- Replace the water instead of only topping it up, so dirt and microbes do not build up.
- Put in only healthy cuttings cut with sterile tools. All the stems share one tank, so one diseased stem affects them all.
- Check the sprayers for blockages, so every stem stays wet.
Translator’s note: The pump warms the water. In a 30–35 °C room, the tank can get warm enough to encourage root rot; see Running Hydroponics at 31 °C Reservoir Temperature. A power cut stops the pump, and bare stems dry out fast. Run the cloner in an air-conditioned room, and keep a domed tray of rockwool cubes ready as a backup.
What to do: Write the cleaning date on the cloner after every batch, and do not start a new batch until it has been cleaned.
Willow water: what it can and cannot do
Soaking or simmering young willow shoots to make a free rooting liquid is old garden advice. The idea has a real basis, because willow contains plant hormones and salicylic acid. The problem is that it is far too weak.
- The dose is far too low. IBA dissolves in water only up to about 250 ppm at 20 °C, and a kitchen extract comes nowhere near that. Products for soft cuttings use roughly 500–1,500 ppm or more, and Clonex uses 3,000 ppm.
- What willow contains is disputed. Willow is often said to contain IBA. But the auxin more often reported in willow is IAA (indole-3-acetic acid), which breaks down quickly. Salicylic acid is not a rooting hormone, though it may help one work.
- The trials are weak. A 2018 Canadian study on cannabis cuttings was done by Caplan, Stemeroff, Dixon and Zheng (Canadian Journal of Plant Science). A 0.2% willow-extract gel did clearly worse than a 0.2% IBA gel (2,000 ppm). The IBA gel gave about 2.1 times the rooting success and 1.6 times the root quality. The study had no untreated group for comparison.
Conclusion: willow water cannot replace a rooting hormone with a stated IBA content. If you want to use it, use it together with one, for example as the water for mixing a powder product. Cannabis is a softwood cutting (a young, green stem) and roots fairly easily anyway. Clean tools, putting the fresh cut straight into water and steady humidity matter far more than the hormone. In a hot room, any homemade extract spoils within a day or two, so make small batches and use them fresh.
What to do: If you want to test willow water, compare a small batch treated with IBA plus willow water against a batch treated with IBA alone.
Troubleshooting
| Problem | Likely cause | What to do |
|---|---|---|
| Cuttings wilt fast | Low humidity, air in the xylem | Put each cutting into water right after cutting; raise humidity |
| Slow rooting or no roots | Temperature too low, no hormone, old or woody cutting | Check temperature (22–23 °C), use rooting gel, choose younger branches |
| Stem rots at the base | Too much moisture, poor drainage | Water less, improve airflow, check that the medium drains |
| Mother is declining | Salt buildup, root-bound | Flush with plain water, trim the roots (bonsai method in Part 1), repot |
| Clones turn yellow | Normal early stress, or too much light | Lower the light intensity; make sure humidity is high enough |
| Hermaphrodite flowers | Feminised-seed genetics under stress | Select mothers from regular seed; keep stress low |
Translator’s note: In Thai rooms, also check for the opposite of the second row: temperatures above the 25 °C top of the rooting range.
What to do: Keep a rooting log for every batch. Record the date, which mother, how many cuttings, the hormone, the dome temperature and how many rooted. When a batch fails, compare the log with this table.
Putting it all together: a sample home setup
- 1–3 bonsai mothers (mothers kept small by pruning shoots and roots; see Part 1) in a 60 × 40 cm space under T5 fluorescent tubes on 18/6
- Feeding: a mother-plant nutrient twice a month, plain water otherwise
- Cutting schedule: every 2–3 weeks, 10–20 cuttings per session
- Rooting station: a small propagator with rockwool cubes, Clonex gel, 22–23 °C and high humidity
- Root trimming: twice a year on each mother
- Seaweed extract: applied 7 days before each cutting session
Once it is running, this setup gives you a steady supply of identical plants that perform predictably. To plan cuttings so that one room is always flowering, see Two-Room Perpetual Harvest.
Translator’s note: In Thailand, add two things to this list: an air-conditioned space for the rooting station, and a timer that keeps time through power cuts.
What to do: Start small, with one mother and one batch of 10 cuttings. Record how many root. Add more mothers only once most of your cuttings root reliably.
If you root cuttings in Thailand or elsewhere in Southeast Asia, post your method below this topic. Include your room temperature, rooting method, hormone and how many cuttings rooted. Questions are welcome too.
References
- Caplan D, Stemeroff J, Dixon M, Zheng Y (2018). Vegetative propagation of cannabis by stem cuttings: effects of leaf number, cutting position, rooting hormone, and leaf tip removal. Canadian Journal of Plant Science 98(5): 1126–1132. https://doi.org/10.1139/cjps-2018-0038