For a number of years, I wanted to start growing some of my own food but I lived in a single bedroom apartment with no yard. Although my unit did have a nice balcony, I was not sure the best approach to take when gardening on top of concrete.
The result of my experiments, conducted over about three years, is what I'm calling the microponics design. I believe the microponics design is the most space efficient method that exists for growing plants in an apartment or condo. See our Urban Food Wall post to see an example garden that I built using this system. Before I get into the particulars of the microponics design, let's examine how I arrived at this approach.
Growing in Water vs. Growing in Soil
You may be thinking: "Wait...I can grow my plants in water?" Yes! Many people don't realize that plants can directly grow in water rather than soil if the water has sufficiently high levels of oxygen. For this requirement, I used a tiny air pump to constantly push bubbles into the water, exactly like I would do if I had a typical aquarium.
Most people just put their plants in pots filled with soil when they do their indoor or porch gardening. I personally observed that plants grow very slowly in soil. On a larger property, the slower growth rate is completely acceptable, but when space is limited, I want to have super productive plants that are growing as fast as possible. In direct comparison tests I conducted with tomatoes, the plants grown in water grew over twice as quickly as the plants grown in soil. It also turned out to be more interesting to watch the plants grow when they were growing more quickly in the water.
A plant in a pot of soil needs to be watered and then that water drains out of the bottom of the pot, creating a mess. Most nicer gardening pots have a small tray to catch overflow water, but I found the water would still tend to spill to some extent. This is not ideal if the area is a hardwood floor in your home. In contrast, when plants are grown in water, the water is in a self contained container which is easily refilled without spillage into the neighboring areas of the room or porch.
A Quick Introduction to Hydroponics and Aquaponics
Growing plants in water is typically called hydroponics. Traditional hydroponics involves adding liquid nutrients to the water to provide an optimal environment for plant growth. It sounds great in theory, but in practice it's very hard to get the nutrient levels correct, so plants often get burned from too much fertilizer (also known as nutrient burn). I also found that the water required constant pH and nutrient monitoring, which was a pain.
However, there is a much better approach to growing plants in water called aquaponics. In aquaponics, fish are added to the water and their pee is the fertilizer. To be more precise, the fish pee out ammonia, which is then broken down by good bacteria into nitrites. Another good bacteria takes the nitrites and further breaks them down into nitrates. Plants then directly consume nitrates as an organic fertilizer (see helpful diagrams here and here).
I found the aquaponics approach to be superior to hydroponicsin every way. You don't have to buy expensive hydroponic fertilizers. You don't have to carefully watch the pH level of the water because the system tends towards stability rather than instability. I also completely loved watching the little fish swim around. It's very relaxing if you have't tried it.
As far as fish food, it turns out that kind of takes care of itself since fish eat algae. Algae is going to start forming in your system anyway, which means once this happens you don't have to feed the fish at all. As a result, the fish basically take care of themselves while adding to the whole ambiance of the setup.
The Microponics Design
When growing plants in water, there are a variety of possible approaches. You can grow your plants directly in a container of water (assuming it's properly oxygenated), an approach called "deep water." Some people have the plants in a container that fills up with water (simulating a flood), which then drains out of the container once totally filled. This is called the flood and drain system. A third approach is to grow the plants in running water recycling through the system, which simulates a small stream. Other approaches involve wicking water through soil ("wicking beds") or spraying the plants' roots with water while suspended in air ("aeroponics").
The microponics design employed here uses the deep water approach; we are going to simply grow the plants directly in water. Here is a quick video showing a basic microponics setup before I added the fish:
Here's a quick one of a microponics tank once the fish have been added. You can observe that the fish get to swim around and interact with the roots of the plants. Both the fish and the plants seem to really like it.
How to Build Your Own Microponics System
Approximate Time Commitment
It will take probably an hour to set up the first time.
About 2 square feet of growing space and then maybe another 1/2 square foot for the pump. This should be by a window so it can get some sunlight or under some sort of artificial light if no window is available.
- 1 Small Aquarium (get two if you want your system to convert to a mini greenhouse in the winter)
- 1 Small Air Pump for Aquariums
- 1 Aquarium Heater (optional if indoors)
- 1 Kneeling Pad for Gardeners (optional but highly recommended)
- Air Tubing
- 1 Long Air Stone
- 2 Square Net Pots
- Hydroponic Growing Medium or Lava Rocks
- Starter Plants or Plant Seeds.
- Filtered Water (ideally filtered via Reverse Osmosis or Zero Water, but bottled water is acceptable)
- 1 - 2 Cups of Water from a stream or lake, taken from an area with moving water
- Baby Goldfish or any other small fish of your choosing.
- Fish food for the first week or so until the algae forms (avoid any fish food that says it will "clear the water").
1) Lay out the kneeling pad where you are going to locate your microponic garden and then set the aquarium tank on top of the kneeling pad.
2) Lay out the air stone inside of the empty aquarium, in the middle.
Note: the following pictures show two units next to each other to achieve more of a square shape. The aquariums may be combined in various ways to create different shapes, for example, a linear garden.
You also want to add the aquarium heater at this point (if you are including one), but don't plug it in until the unit is filled with water.
3) Connect the air stone to the air tubing and then connect the other side of the air tubing to the air pump. Go ahead and plug in the power cord for the air pump into an electrical outlet as well. You want the pump running before you add the water.
4) Add the net pots to the top of the aquarium. Fill with either lava rocks, hydroponic growing medium, or a combination of both. I often plant my starter plants into the rocks as I'm filling up the pots with growing medium.
5) Fill the aquarium with the filtered water and the 1 - 2 cups of water from a natural water source such as a clean, moving stream or lake. Plug in the heater and let the unit sit for about six hours or until the water is warm to the touch. You want to avoid adding the fish until the water is warm.
6) Add the fish and some fish food. Your garden is now operational!
Later, when winter comes, you can add a second aquarium tank, flipped over upside down, to function as a very effective miniature greenhouse. The aquarium heater does a good job of keeping the plants from freezing. My plants weathered roughly 20 degree Fahrenheit weather using this greenhouse.
For very cold climates, cover the mini-greenhouse at night with a comforter or blanket and then cover that with a tarp so it stays dry. This was not necessary in my climate but it may be depending on how cold your winters get.
Thank you for joining us for this introduction to how to grow a lot of food in a tiny space! We hope this microponics design increased your understanding of the options available to you and perhaps inspired you to set up your own microponics garden!
The microponics design also works as an indoor garden or it could be used as an herb garden. In this example, it was a vegetable garden. This approach to urban gardening uses a container gardening approach with water rather than soil. It works well as a balcony garden and, in fact, this was the original use-case. The mciroponics system is great for apartment gardening or gardening in a condo unit.