While looking for ways to generate income on our farm, we’ve come across what is called the “Kratky Method” of hydroponics. It is described as a “set it and forget it” method. It does not require any electricity or flow of water and aside from the initial “planting”, there is minimal labor involved. The amount of water needed from seedling to maturity is vastly reduced when compared to the amount needed if the plant were in the ground. A head of lettuce will need 15-20 liters using the Kratky Method, in the ground, a head requires around 250 liters! So this method is superb for areas with water shortage or just to save on labor.
The secret is the placement of the plant roots in the hydroponic water solution. This can be achieved a couple of different ways – one, is to purchase what is known as net cups (available from Amazon) the second, which is what we used, is to cut 6mm holes into a plastic drinking cup (sides and bottom). The cup holds the seedling and allows only the tail of the roots to be submerged in water, while leaving an inch or so of the root exposed to the air. This exposed root provides the needed oxygen for the plant without circulating water.
The NPK (nitrogen, phosphorus, potassium) ratio is specific for each type of plant and can easily be found online in a search. Micronutrients are also included in the mix to mimic what is found in soil -Boron, Copper, Manganese, Zinc, Molybdenum, and chlorine – this is called the Master Blend. In addition, the ph of the water should be in a range of 6.4 - 6.7 and whatever is needed to achieve that can be added to your mix (lemon juice works well if it’s too high).
In our area, the custom mixed fertilizer is about $1.30 a kilo, including the water ph adjustment. Here in the states, they sell a Master Blend with a NPK of 4-18-38, which includes the micronutrients. Since not much will grow with only 4 parts nitrogen, Calcium Nitrate is added to increase the ratio as needed. You will also have to add some Epsom Salt (Magnesium Sulfate). This helps blend the nutrients and prevents algae from growing in the water. To further prevent algae, your plant box must NOT allow any light to filter in.
Just to give an idea of the quantities, for lettuce you would need 10 grams Master Blend, 10 grams Calcium Nitrate, and 5 grams Epsom Salt per 20 liters (approx 5 gallons) of water. Even though the blend is specific for lettuce, we stuck some cucumbers, tomatoes and peppers in the same mix and they are doing well (so far) as Mother Nature allows us a margin of error.
We have watched a series of videos on YouTube by mhpgardener in Virginia. He is easy to understand and rather entertaining. Our first experiment has been with 160 heads of Boston lettuce and a few tomatoes, cucumbers and pepper plants. Below are photos of the experiment and we are extremely pleased with the results. The total time for lettuce is about 60 days. We are planning to do 4 or 5 grows per year of several thousand heads to generate a good income and much needed food for the people in our region!
While this method works best inside a green house, our experiment was done outside. The only problem that may be encountered outside is plants blowing away in the wind or the plant boxes taking on rain water, diluting the mix of nutrients. In our area, rain is usually not an issue this time of year, but we have had few heads of lettuce blow away.
When fully operational, we will be doing some boxes inside a green house, and others still outside, but with a protective plastic canopy fashioned out of flexible plastic tubing. For any communities looking for easy ways to generate income or just food for the group, this Kratky Method is the best we’ve found for minimal time, labor and water. The pickin is easier too (no bending over) and the produce is clean!
Since these pictures were taken, we've harvested the lettuce and the cucumbers are producing. The nitrogen was too high for the cucumbers, so the leaves of the plants yellowed, but the cucs are very tasty!
The secret is the placement of the plant roots in the hydroponic water solution. This can be achieved a couple of different ways – one, is to purchase what is known as net cups (available from Amazon) the second, which is what we used, is to cut 6mm holes into a plastic drinking cup (sides and bottom). The cup holds the seedling and allows only the tail of the roots to be submerged in water, while leaving an inch or so of the root exposed to the air. This exposed root provides the needed oxygen for the plant without circulating water.
The NPK (nitrogen, phosphorus, potassium) ratio is specific for each type of plant and can easily be found online in a search. Micronutrients are also included in the mix to mimic what is found in soil -Boron, Copper, Manganese, Zinc, Molybdenum, and chlorine – this is called the Master Blend. In addition, the ph of the water should be in a range of 6.4 - 6.7 and whatever is needed to achieve that can be added to your mix (lemon juice works well if it’s too high).
In our area, the custom mixed fertilizer is about $1.30 a kilo, including the water ph adjustment. Here in the states, they sell a Master Blend with a NPK of 4-18-38, which includes the micronutrients. Since not much will grow with only 4 parts nitrogen, Calcium Nitrate is added to increase the ratio as needed. You will also have to add some Epsom Salt (Magnesium Sulfate). This helps blend the nutrients and prevents algae from growing in the water. To further prevent algae, your plant box must NOT allow any light to filter in.
Just to give an idea of the quantities, for lettuce you would need 10 grams Master Blend, 10 grams Calcium Nitrate, and 5 grams Epsom Salt per 20 liters (approx 5 gallons) of water. Even though the blend is specific for lettuce, we stuck some cucumbers, tomatoes and peppers in the same mix and they are doing well (so far) as Mother Nature allows us a margin of error.
We have watched a series of videos on YouTube by mhpgardener in Virginia. He is easy to understand and rather entertaining. Our first experiment has been with 160 heads of Boston lettuce and a few tomatoes, cucumbers and pepper plants. Below are photos of the experiment and we are extremely pleased with the results. The total time for lettuce is about 60 days. We are planning to do 4 or 5 grows per year of several thousand heads to generate a good income and much needed food for the people in our region!
While this method works best inside a green house, our experiment was done outside. The only problem that may be encountered outside is plants blowing away in the wind or the plant boxes taking on rain water, diluting the mix of nutrients. In our area, rain is usually not an issue this time of year, but we have had few heads of lettuce blow away.
When fully operational, we will be doing some boxes inside a green house, and others still outside, but with a protective plastic canopy fashioned out of flexible plastic tubing. For any communities looking for easy ways to generate income or just food for the group, this Kratky Method is the best we’ve found for minimal time, labor and water. The pickin is easier too (no bending over) and the produce is clean!
Since these pictures were taken, we've harvested the lettuce and the cucumbers are producing. The nitrogen was too high for the cucumbers, so the leaves of the plants yellowed, but the cucs are very tasty!