Here’s an effective and low-cost method to propagate plants easily without spending your time constantly checking soil moisture. It’s for all those who love plants but tend to… well… forget about them. The method is also useful for people who can’t always be around their plants — for example, those who live in the city and have a garden or land in the countryside. Plus, it’s perfect for experimenting with cuttings or sowing seeds that are known to be difficult or slow to germinate, like fruit tree pits.
Let’s be honest: no professional grower will use this method. You need to have the bottles at hand. But for amateurs, it works really well.
What you need
Nothing exotic.
- Two plastic bottles of the same size, either cylindrical or square. Manufacturers love to invent “sexy” shapes to catch your eye, but that’s not ideal in this case. At home, we use lots of simple 2-liter bottles that once contained our homemade apple juice.
- A piece of flexible plastic, such as the bottle’s label.
- Some gravel or expanded clay pellets.
- A light substrate: a mix of potting soil, garden soil, sand, or peat (peat is best avoided, as we humans are overexploiting this resource). It doesn’t need to be nutrient-rich — the key is that it’s light and airy.
- Water.
- Optional: a bit of charcoal, which helps keep the water cleaner. Avoid industrial barbecue charcoal, often coated with chemicals to make lighting easier. Place the charcoal in the reservoir.
How to propagate your plants
- The reservoir
Cut the top off one bottle: this will become the reservoir. Add a bit of charcoal. - The container
Cut the bottom off another bottle: this inverted part will hold the substrate and the cuttings. - The wick
Before fitting the two parts together, insert a strip of plastic into the neck of the container, making sure it touches the bottom of the reservoir. This wick allows the water to rise by capillary action. Choose a non-organic material so it doesn’t rot over time. - Assembly
Turn the part with the neck upside down and place it inside the reservoir. At this stage, to make refilling easier later, create a small gap between the two (for example by wedging in a small piece of wood or making a little “wave” in the container) so you can easily refill the reservoir. - The drainage layer
Place a thin layer of gravel or clay pellets at the bottom of the container, around the wick. This prevents the substrate from sitting directly in the water. - The substrate
Add the soil mix, moistened well — not soaking wet, but nicely damp. - Cuttings or seeds
Place your cuttings or sow your seeds. - Filling
Pour water into the reservoir, up to the level of the gravel but no higher. If you overfill, you risk root rot through lack of oxygen.
Once the root system is well developed, the plants can be transplanted. A year is a good timeline.
Three extra tips
Mini greenhouse (optional): Some type of cuttings need a cover, you can use the top of the bottle (the one that became the reservoir) as a little cloche. This keeps a humid atmosphere around the plant, reducing transpiration — which is crucial at the beginning for some cuttings, when it has no roots yet.
Cuttings should generally be placed in a shaded spot, not in full sun. Autumn cuttings can tolerate sunlight, but spring ones should be moved to a shadier place.
If, after a few months, the leaves turn yellow, that’s probably a sign that fertilization is needed. Diluted urine (one part urine to ten parts water) makes an excellent natural fertilizer, but any gentle fertilizer will do.
The principle behind it all
The key is capillarity. Water slowly rises from the reservoir into the substrate, just like a sponge soaking up water. It’s the same phenomenon that makes bricklayers install a waterproof membrane under walls to prevent moisture from rising. As a result, the plant “helps itself” to water as needed.
Other physical concepts are also at play: surface tension, the balance between gravity and capillary forces, evapotranspiration… but honestly, I don’t fully understand all of them — and as gardeners, we don’t need to. What matters is that it works. We just want to propagate plants, not get a PhD in physics.
This type of setup is essentially a miniature version of a self-watering planter. For those who’d like to DIY this kind of system on a larger scale, the keyword is “wicking bed”.
Practical advantages of this method for plant propagation
You can forget about your cuttings for a while. The reservoir can last several weeks, even one to two months in winter, and from a few days to two weeks in summer, depending on the ambient temperature and the stage of development.
The plant takes exactly the amount of water it needs — no excess, no sudden drying out. This regulation of humidity is often the key difference between a cutting that succeeds and one that rots or dries up.
The video version
This article is the written version of a practical video we made. You can watch it here (in Romanian):
Going further: permaculture principles in action
As you know, permaculture is a design method underpinned by ethics and principles. This way of propagating plants illustrates several key permaculture principles, which you can explore on the Permaculture Principles website or during our certified permaculture design courses. Here are the ones:
- Capture and store energy.
The system allows water to be stored in the reservoir and released slowly, just like well-structured soil would. - Obtain a yield.
It produces new plants with minimal effort, which is exactly what good design aims for. - Use and value renewable resources.
Here, a plastic bottle considered waste becomes a resource. We extend its life by turning it into a useful tool instead of throwing it away. It’s a concrete example of the principle of producing little waste and valuing diversity. - Apply self-regulation and accept feedback.
The plant becomes its own watering regulator. It takes what it needs, when it needs it. The system self-regulates and reduces maintenance work. - Use small and slow solutions.
This is a far cry from industrial greenhouses or energy-hungry automated systems. It’s a low-tech solution that relies on time and simplicity.