Kratky Newbie
Hello, I’m a newbie and I am doing the kratky method with lettuce and herbs. I have 4 Swiffer containers with 2 lettuces each. I also have lettuce in 20oz bottles. When I moved the seedlings to their containers on 5/29/18, I used 1/2 strength nutrients. I grow the plants indoors under lights. The plants have used close to 1/2 of nutrient solution. When should I bump the plants up to full strength nutirents? Should I pour out the old nutrients and start fresh with full strength nutrients? If I do, it wont go to waste because I can apply to my plants outside.
Usually you use full strength solution (master blend for lettuce) Use an aerator to add oxygen and keep the mosquitoes down. It also enhances growth. You grow out your lettuce seedlings in plug trays. We use oasis foam since it won't fall apart and leave silt on the bottom of the tank. Since lettuce is a 30 day crop, you should be able to complete the cycle on just one tank full. Kratky grew lettuce on 2 liter bottles. The solution is supposed to evaporate and should not be topped off since that will change the dilution. As long as some of the roots still touch the water, the rest of the roots will be air roots. As long as the roots are white, they are healthy.
https://www.ctahr.hawaii.edu/hawaii/dow ... method.pdf
This is an exerpt from Kratky's paper.
"The basic concepts of non-circulating hydroponic systems (Kratky, 1996b) include:
1.) The upper part of the root system should be exposed to air with high relative
humidity; 2.) Roots must not be allowed to dry out; 3.) The lower portion of the root
Kratky, B.A. 2004. A suspended pot, non-circulating hydroponic method. Proceedings of
the South Pacific Soilless Culture Conference, Acta Hort. 648. p. 83-89.
system should gather water and nutrients; 4.) Nutrient solution level may remain the same
or be lowered, but it may not be raised or else the roots will ‘drown’.
In the suspended pot, non-circulating hydroponic system, plants grow in a small
amount of substrate held by a perforated container which is supported by a fixed cover
over a tank (Fig. 1). The lower portion of the container is originally immersed in nutrient
solution. The young plant is then automatically watered by capillary wetting of the
substrate. The nutrient solution level drops below the container as the plants grow. At
this point, direct capillary wetting of the substrate is no longer possible, but the newly
emerging roots are quite capable of absorbing the nutrient solution. These concepts are
the subjects of U.S. Patents 5,385,589 and 5,533,299 (Kratky, 1995, 1996a).
Fig. 1. A model suspended pot, non-circulating hydroponic system after the nutrient
solution has dropped below the seedling container..
4-Liter bottle method
The simplest version of this method is a 4 liter plastic juice bottle containing water
plus 5 grams of Chem-Gro 10-8-22 hydroponic fertilizer (Fig. 2, Kratky, 2002). The
bottle should either be covered or darkened to discourage algae growth. A 7.5-cm long
net pot (a tapered plastic pot with slits to allow root emergence) is filled with growing
medium and lettuce is seeded or transplanted. Alternatively, a tapered forestry tube with
additional holes drilled in the sides may be used. The net pot is supported by the neck of
the bottle. The lower 3 cm of the net pot is immersed in the nutrient solution and the
entire medium in the net pot becomes moistened by capillary action. Thus, the young
plant is automatically watered.
As the plant grows, the nutrient solution drops below the net pot so that it may no
longer be directly moistened by the nutrient solution. However, the lower portion of the
newly developing active root system absorbs the necessary water and nutrients for the
plant. Meanwhile, roots in the moist air space above the nutrient solution
Nutrient
Solution
Air space with
high relative
humidity
Top
cover
Kratky, B.A. 2004. A suspended pot, non-circulating hydroponic method. Proceedings of
the South Pacific Soilless Culture Conference, Acta Hort. 648. p. 83-89.
morphologically change by becoming thicker and more branched so that they may absorb
more oxygen.
Fig. 2. Lettuce growing in a 4-liter plastic juice bottle.
The plant grows to maturity (usually about 6 weeks from seeding) and the nutrient
solution level typically drops 15-25 cm below the original level because no additional
nutrient solution is added to the bottle. The increasing zone of moist air between the
nutrient solution and the net pot does not hinder plant growth. Lettuce experiences its
normal logarithmic growth pattern with very rapid growth near maturity. In Hilo, Hawaii,
a 200 gram lettuce plant typically only consumes about 3-4 liters of EC 1.5 mS nutrient
solution. The lettuce is of gourmet quality.
The 4 liter bottle method is only suitable for short-term crops like lettuce which
require less than 4 liters of water for their lifespan. It is possible to grow longer term
crops like cucumbers and tomatoes which require huge amounts of water in a 4 liter
bottle by allowing the nutrient level to drop about 20 cm and then maintain that level with
a float valve or by adding nutrient solution to maintain a level in about a 3 cm range, but
this is cumbersome and defeats the simplicity feature of this method. An alteration of this
method is to grow 3 or 4 plants in a 20 liter plastic bucket.
Gardeners can use this method to grow plants on lanais, porches and under the
overhangs of buildings. Educators may use this inexpensive method to teach students
about plant growing concepts. The bottles can be prepared in one class period and
require no additional maintenance so there is no need to worry about weekend watering.
Researchers and farmers may use this method to conduct nutritional studies, test
pesticides and produce seed"
https://www.ctahr.hawaii.edu/hawaii/dow ... method.pdf
This is an exerpt from Kratky's paper.
"The basic concepts of non-circulating hydroponic systems (Kratky, 1996b) include:
1.) The upper part of the root system should be exposed to air with high relative
humidity; 2.) Roots must not be allowed to dry out; 3.) The lower portion of the root
Kratky, B.A. 2004. A suspended pot, non-circulating hydroponic method. Proceedings of
the South Pacific Soilless Culture Conference, Acta Hort. 648. p. 83-89.
system should gather water and nutrients; 4.) Nutrient solution level may remain the same
or be lowered, but it may not be raised or else the roots will ‘drown’.
In the suspended pot, non-circulating hydroponic system, plants grow in a small
amount of substrate held by a perforated container which is supported by a fixed cover
over a tank (Fig. 1). The lower portion of the container is originally immersed in nutrient
solution. The young plant is then automatically watered by capillary wetting of the
substrate. The nutrient solution level drops below the container as the plants grow. At
this point, direct capillary wetting of the substrate is no longer possible, but the newly
emerging roots are quite capable of absorbing the nutrient solution. These concepts are
the subjects of U.S. Patents 5,385,589 and 5,533,299 (Kratky, 1995, 1996a).
Fig. 1. A model suspended pot, non-circulating hydroponic system after the nutrient
solution has dropped below the seedling container..
4-Liter bottle method
The simplest version of this method is a 4 liter plastic juice bottle containing water
plus 5 grams of Chem-Gro 10-8-22 hydroponic fertilizer (Fig. 2, Kratky, 2002). The
bottle should either be covered or darkened to discourage algae growth. A 7.5-cm long
net pot (a tapered plastic pot with slits to allow root emergence) is filled with growing
medium and lettuce is seeded or transplanted. Alternatively, a tapered forestry tube with
additional holes drilled in the sides may be used. The net pot is supported by the neck of
the bottle. The lower 3 cm of the net pot is immersed in the nutrient solution and the
entire medium in the net pot becomes moistened by capillary action. Thus, the young
plant is automatically watered.
As the plant grows, the nutrient solution drops below the net pot so that it may no
longer be directly moistened by the nutrient solution. However, the lower portion of the
newly developing active root system absorbs the necessary water and nutrients for the
plant. Meanwhile, roots in the moist air space above the nutrient solution
Nutrient
Solution
Air space with
high relative
humidity
Top
cover
Kratky, B.A. 2004. A suspended pot, non-circulating hydroponic method. Proceedings of
the South Pacific Soilless Culture Conference, Acta Hort. 648. p. 83-89.
morphologically change by becoming thicker and more branched so that they may absorb
more oxygen.
Fig. 2. Lettuce growing in a 4-liter plastic juice bottle.
The plant grows to maturity (usually about 6 weeks from seeding) and the nutrient
solution level typically drops 15-25 cm below the original level because no additional
nutrient solution is added to the bottle. The increasing zone of moist air between the
nutrient solution and the net pot does not hinder plant growth. Lettuce experiences its
normal logarithmic growth pattern with very rapid growth near maturity. In Hilo, Hawaii,
a 200 gram lettuce plant typically only consumes about 3-4 liters of EC 1.5 mS nutrient
solution. The lettuce is of gourmet quality.
The 4 liter bottle method is only suitable for short-term crops like lettuce which
require less than 4 liters of water for their lifespan. It is possible to grow longer term
crops like cucumbers and tomatoes which require huge amounts of water in a 4 liter
bottle by allowing the nutrient level to drop about 20 cm and then maintain that level with
a float valve or by adding nutrient solution to maintain a level in about a 3 cm range, but
this is cumbersome and defeats the simplicity feature of this method. An alteration of this
method is to grow 3 or 4 plants in a 20 liter plastic bucket.
Gardeners can use this method to grow plants on lanais, porches and under the
overhangs of buildings. Educators may use this inexpensive method to teach students
about plant growing concepts. The bottles can be prepared in one class period and
require no additional maintenance so there is no need to worry about weekend watering.
Researchers and farmers may use this method to conduct nutritional studies, test
pesticides and produce seed"
I would go and did go full strength after my Kratky plants used up a good portion of their 1/2 strength nutrient water. I had a few that were stuck at one stage and when I switched to the full strength they took off. For mine I changed the nutrient water out completely.
I am mid-newbie Kratky and this works for me.
I have been growing Kratky tomatoes ,peppers and Canteloup since January, very fun stuff!
I am mid-newbie Kratky and this works for me.
I have been growing Kratky tomatoes ,peppers and Canteloup since January, very fun stuff!
For longer crops and heavy feeders, changing out the nutrient solution works better since it is usually not possible for the nutrient solution to last for the entire crop cycle. Lettuce seedlings planted out when they are about 2 inches tall (about 2 weeks old). We put the seeds in oasis plugs. The tray was bathed in hydroponic solution (flow by), so that the seedling would develop water roots.
The seedlings placed in the net pot on top of the bottle or on the raft. Since lettuce is a short crop ready in 4-6 weeks, the original solution is enough to last till the lettuce is harvested.
The seedlings placed in the net pot on top of the bottle or on the raft. Since lettuce is a short crop ready in 4-6 weeks, the original solution is enough to last till the lettuce is harvested.