Self-watering pots are a wonderful idea! They reduce the amount of work you have to do to keep your precious plants watered and they are very water efficient, providing a reservoir so the plant stays hydrated but with a minimum of evaporation. Unfortunately my experience with the commercial models is that the reservoir is way too small for the size of the pot and resultantly the size of the plants being grown. I prefer the homemade variety, you can make them to your own specifications.
The downside is of course that no matter whether your self-watering containers are store bought or home builds, it would be somewhat expensive to convert all potted plants over to this style of watering. This is especially true for those container-growing enthusiasts amongst us. So what is the answer?
I’m glad you asked!
The answer is to convert all of your existing growing containers over to the “bottle and wick” watering system. It is cheap, very water efficient and reasonably easy to do, especially at repotting time.
The idea is that a synthetic rope wick of the right type connects an external reservoir to the root zone of the plant in the pot, the water travelling down the wick by capillary action. This allows a large reservoir to be connected to a standard pot so that it will have all the advantages of a self-watering b pot, but without the expense.
How To
The first thing is to get hold of some material to use as the wick. Nylon or polyester braided rope is ideal (polyethylene is hydrophobic and so not a good choice). Unfortunately in many cases the material the rope is made from is not put on the label, in which case you could ring or email the company to find out or just use one which is labelled if you can find one. I was able to find some labelled as being polyester where other types from the same manufacturer were not labelled.
Cut the rope to size allowing enough length so that the rope will go to the bottom of the reservoir and coil around, run between the reservoir and the pot and still have enough rope left over to coil around the inside of the pot.
To keep down evaporation from the wick between the reservoir and the plant pot some plastic tubing, just a bit bigger than the rope, will also be needed. I got 6mm rope and 8mm tubing, although larger diameter rope would allow more water to be transported. Cut the tubing to size so that the rope will be covered from where it leaves the reservoir to where it enters the soil surface at the pot.
To make it easier to thread the rope into the tubing, apply a small flame gently to the free end of the rope so that it melts down a bit, this keeps the core and outer layers of the rope together and makes passage through the tubing easier. I used a needle to thread some cotton through the free end of the rope, then holding the pre-cut tube vertically, allowed the needle to act as a weight and pull the cotton through the tubing from end to end. I could then grab the cotton and use it to pull the rope through the tube so there was rope hanging out each end of the pre-cut tubing.
To make the reservoir, I recycled a two litre plastic milk bottle. I cut a cross up near the top of the bottle and inserted through it enough of the rope so that it went down to the bottom of the bottle and coiled around a bit. I then inserted the plastic tubing around the rope so that it fitted through the hole leaving no rope exposed.
I place some potting mix into the pot so that it was about a third full, then took the free end of the rope and ran it down onto the soil surface. I placed the plant in place and then filled the pot with potting mix, ensuring the rope wick is fully covered with soil. I then filled the bottle with water. Make sure the bottle lid is not on so tightly as to cause a vacuum as the water is drawn from the bottle, otherwise the water will stop flowing.
The water should move along the rope wick by capillary action and you can see the progress of the water through the clear tubing. It took a few hours to move along the 40cm or so of the wick I made and you could see the progress of the water through the clear tubing..
