In this article I will explain how to easily make a self-irrigating pot with a ordinary PET bottle.
No need to be good at DIY, you can recycle PET bottles that have contained a drink and you may have a piece of rope or nylon tape lying around somewhere in a closet or drawer.
Watering is often guesswork:
- you don’t know how much water your plant needs: not everybody is a plant geek knowing hundreds of plants by name and culture conditions
- the surface layer may be dry but the lower soil below can be wet and the roots may rot
- one day it’s very hot, the next it’s cooler: your plant needs more or less water depending on the weather
In short, it may be difficult to guess if your plant needs watering or not.
Is it beautiful?
Nope, not at all. This self-irrigating put is ugly as hell. But you can dress it with a sheet of colored paper or something else that looks better.
Which will, as a bonus, prevent algae growth in the water reservoir.
Is it suitable for all plants?
Yes, both for plants that require very little water to plants that need to be in a permanently moist substrate. How come? Because the plant draws the amount of water it needs.
No, not for all plant sizes: a plastic bottle is not very big and when the plant becomes too tall, the bottle may fall over at the slightest blow or breath of air.
This self-irrigating pot is particularly suitable for seedlings and cuttings, waiting to be planted in the garden or in a larger pot.
Advantages of self-irrigation:
- Regular water supply: therefore less risk of drying out (unless you forget to fill the reservoir when empty)
- Less frequent watering: maximum once a week, often once a month or even less, depending on the species, size…
- Suitable for all types of plants, from cacti and succulents to marsh plants. Cacti and succulents even grow much better with a regular water supply.
- For cultivation in soil or hydroponics: the type of substrate is irrelevant because the wick brings water to the roots. In hydroponics, add specialized hydroponic fertilizer to each watering.
Disadvantages of a self-irrigation PET bottle:
Plastic bottles are generally transparent and algae can occur in the water reservoir. This can be prevented by surrounding the pot with a sleeve of black or dark paper or cardboard. For a temporary installation it is not very important: I clean the tank at each watering.
Of course, this is not a pot which will be given a nice place in your living room, unless you dress it. But since it is mainly suitable for seedlings and cuttings, it’s not really a problem if you place it on a window sill in the kitchen or any other room.
How do you water it?
Lift the pot containing the plant and fill the reservoir with water till just below the cap.
The first time or if, despite everything, you forgot to water, water a bit on top of the soil to moisten the substrate and the wick.
That’s where the cap comes in: it prevents leakage of soil into the reservoir.
- PET bottle that has contained a drink: being safe for food, they are safe to use for growing veggies and fruit
- a Stanley knife or box cutter
- a piece of nylon rope or tape (nylon does not rot)
- substrate: soil, coconut fiber, expanded clay pellets…
Cut a PET bottle in 2 with a cutter or scissors.
The bottom part of the bottle will be the water reservoir.
The upper part of the bottle with the bottle neck will contain the plant and substrate.
Slit the bottle cap with the cutter, forming a cross.
Cut a piece of nylon rope to the length needed for it to touch the bottom of the reservoir and the roots in the upper part.
Thread the wick through the notch in the bottle cap.
Screw the cap containing the wick back on the bottle.
The cap prevents soil from leaking into the water reservoir but this is not mandatory.
Fill the pot with substrate (soil, coco fibers, expanded clay pellets…).
Place the plant on the substrate and fill the pot with the rest of the substrate.
Voilà, the plant is ready.
Place the plant pot on top of the water reservoir.
This is how it looks once finished.
To water, lift the plant pot and fill the reservoir till just beneath the cap.
The first time, water from above to moisten the substrate and wick. After that, the water will come up by capillarity.