Introduction: Kratky Method Hydroponics Tutorial
In honor of Earth Day, here's a quick and easy one-plant hydroponic system, known as the Kratky Method. It's a great project for reusing containers probably already in your recycling bin and growing some edible veggies at the same time!
Another benefit to the Kratky Method is the fact that there is no need for pumps or electricity like many other hydroponics methods. Once the system is set, the plant roots do all the work! All you have to do is put it in a sunny spot, forget about it for a month or so, and then reap the harvest.
This tutorial will show you how to build the system but won't get into the mixing of nutrients. The size of your container and what you are growing will dictate how much nutrient solution you'll need to use.
There are tons of nutrient solutions available at garden centers and online. Or you could try your hand at mixing your own fertilizer salts and creating your own custom nutrient mix.
You could even make some compost tea from yard and kitchen scraps!
Another option, since there are no pumps (therefore no pumps to clog), is using soil in your pot. You're kind of turning it into a self watering container garden and some of the soil will fall into the reservoir for sure, but it's still a viable solution if specific hydroponics nutrients are not an option.
Container for reservoir with matching lid (Get creative with reusing old containers!)
Pot for plant (Again, reuse old pots or turn plastic recycling into a pot)
Support substrate (rocks, hydroton, even soil)
Scissors, pocket knife, or utility knife
Nail or screw or other marking tool
Hydroponic Nutrient Mix (store bought or homemade) or homemade Compost Tea
pH testing strips or liquid (optional but recommended)
Step 1: Preparing the Lid
Start by stenciling/tracing a hole for your net pot and cutting out said hole.
Do this by flipping the pot upside down (so the circumference of the top rim is what's being marked) and using a nail/screw/knife to mark around the pot's rim.
Next, either punch a hole on the inside of the circle you just drew using a hammer and nail, or drill a hole.
Now use scissors or a knife to cut out the entire disc, using your nail/drill hole as a starting point. It's best to start small, test to see if your pot fits, then remove extra material if necessary. If you cut your hole too big, you run the risk of your pot falling through or not fitting properly.
Once you're satisfied with your hole and the how the pot fits, make sure about 1/2-3/4 of the pot is coming through the bottom of the lid. The plant's roots will need to access the water in the reservoir, so the bottom of the pot should be touching the surface of the nutrient rich water or be just above the water's surface.
Before you fill your reservoir, you can mark a "water line" just above the bottom of the pot as it sits in the reservoir. If your reservoir is translucent or transparent, this should be relatively easy to see. If your reservoir is opaque, you may need to measure or just estimate.
Step 2: Preparing the Pot for Planting
Once your lid is ready and the pot fits properly, it's time to prepare the pot for planting.
I'm using little pebbles/pea gravel, but really any substrate will work to support your plants. Granite gravel, rock wool, or even soil will do the trick here as well. Because this system doesn't use recirculating water pumps, even if some of the soil gets in the reservoir there is nothing to clog! Soil is certainly a good option, too, if finding specific hydroponics nutrients (or making compost tea) just isn't an option.
To prep your pot for planting, put a small amount of substrate in the pot. Then place the plant on said substrate and fill the rest of the pot with substrate to support the stem of the plant.
We've shown a few other options for pots here. I'm using a seedling pot that I found laying around, but you could easily reuse old containers (like this apple sauce cup) by drilling lots of holes and turning them into net pots. Or you could purchase specific hydroponics net pots, like the black net pot example above.
Step 3: Preparing the Reservoir
Your reservoir doesn't need much work, but you will need to mix up your nutrient solution at this point. We aren't detailing the exact nutrients or quantities to use in this tutorial. These will vary based on the size of your reservoir and what types of plants you plan on growing.
Regardless of what nutrient solution or homemade compost tea you choose to use, the mixing principles will remain the same.
First, fill your reservoir roughly half way with, fresh, potable water. If using tap water it's good to let the water sit for a while so that some of the excess chlorine and fluoride can evaporate, but it's not absolutely necessary.
Once half way full, add your nutrient solution or compost tea (follow volume guidelines on the label, based on size of reservoir/volume of water) and stir very well to mix into a homogenous solution.
Finally, fill the reservoir with water to your predetermined "water line" (i.e. where the pot hits or sits just above the water surface) and stir well again.
Using pH strips or liquid indicator, test the pH of your nutrient rich water solution. Try to dial it in to somewhere between 5.5 and 6.5, as most veggies prefer this slightly acidic pH.
Now your Kratky method hydroponic system is complete! Experiment with different plants and different nutrients to get the best results.
Have fun and keep making!