This is a guest post by Mike Lieberman of the Urban Organic Gardener.
Since I started urban gardening in New York City in the spring of 2009, I have mostly been using self-watering containers that are constructed using two 5-gallon containers.
I’ve had success with them on my fire escape in New York and my balcony in Los Angeles. They don’t take up much space and can easily be moved around.
How to Make a Self-Watering Container
If you’ve ever seen any of those "grow box" products, that is what a self-watering container is. It’s just much cheaper to make on your own.
Once you get the tools, most of which you’ll likely have around your home already, it’ll cost you less than $3 to make one. That's much more affordable than the $50+ ones you can purchase.
There are several variations on making these. I’ll share with you the simplest and cheapest one that I’ve been using for the last two years.
Tools you’ll need:
- ¼″ bit
- 3 ½″ hole saw for metal and wood
- 1 ¼″ hole saw for metal and wood
Materials you’ll need:
- Two food grade 5-gallon containers – 1 for planting container and 1 for reservoir container
- ½-pint deli container for wicking basket
You don’t have to buy the 5-gallon containers. I’ve found that businesses like delis, restaurants or flower shops will gladly either give them to you or sell them for $1.
I’ve had people tell me they’ve actually established relationships with local vendors who call and let them know when they have containers to pick up.
Instructions on how to make self-watering containers:
- Use the ¼″ drill bit to drill holes in the deli container.
- Attach the 3 ½″ hole saw attachment to the drill. Drill a hole in the bottom of the container. A counter-clockwise direction works best.
- Reattach the ¼″ drill bit and drill holes in the bottom of the planting container to allow for drainage.
- Put the wicking basket in the middle of the reservoir container.
- Place the planting container in the reservoir container, aligning the wicking basket with the hole in the middle. There will be a little space between the wicking basket and the planting container. You can duct tape the basket to the bottom of the container, but it’s not necessary.
- Hold the containers up to the light. You should be able to see through the reservoir container where the planting container is.
- Using the 1 ¼″ hole saw, drill a hole ¼″ in the reservoir container below where the planting container is. This is the hole you will water the plant from.
- That’s it. You’re done!
How Self-Watering Containers Work
With a traditional container, you water the plant from the top. A percentage of the water you pour doesn’t even make it to the roots. By contrast, in self-watering containers the plants' roots suck up the water from the reservoir container below.
As I mentioned earlier, self-watering containers are made up of two 5-gallon containers. They are called the reservoir and planting containers. The outside container is the reservoir container. It holds the wicking basket and the water.
Following the instructions above, the planting container is placed inside of the reservoir container with the deli container centered.
When you put the self-watering container together, fill the wicking basket with soil and then moisten with water. Then add more soil to fill the planting container, moistening that as well.
When the pot has been filled to about 2-3 inches from the top, place your plant and surround it with more soil, making sure to keep it moist.
You can water the self-watering container by removing the planting container and pouring water directly into the reservoir container until it reaches the overflow hole.
Since there are holes in the wicking basket with the soil, it will soak up the water and allow the plants' roots to drink up the water as needed. This is a more natural way for the plants to soak up water as opposed to watering them from the top. It also makes it easier to never over-or under-water the plant because you can check the overflow hole.
Depending on the plant, temperature and sunlight, water the plant just once per week -- or less. I’ve gone away for up to three weeks and they’ve been fine.
Updated January 30, 2018.