Simple non-circulating hydroponic method for vegetables


Hydroponics is the most common method of soil-less culture (growing agricultural plants without the use of soil), which includes growing plants either on a substrate or in an aqueous medium with bare roots. Non-circulating hydroponic methods, importantly, do not require electricity or a pump.
With the method presented in this document, the entire crop can be grown with only an initial application of water and nutrients. No additional water or fertilizer are needed. The crop is normally terminated when most of the nutrient solution is consumed.
This document provides two detailed step-by-step description of simple, non-circulating hydroponic growing kits for growing vegetables at a small scale, one for short term vegetables (e.g. lettuce or kai choy) and the other for long-term vegetables (e.g. cucumber or tomato).



Hydroponics is the most common method of soil-less culture (growing agricultural crops without the use of the soil), which includes growing plants either on a substrate or in an aqueous medium with bare roots. This solution provides all of the necessary nutrients for plant growth. Irrigation systems can be integrated within the substrates or surround the plants’ roots directly, thereby introducing a nutrient solution to the plants’ root zones.

Non-circulating hydroponic methods refer to closed systems that utilize water and fertilizer very efficiently and are also known as “Kratky hydroponics”. These systems avoid the additional production costs and complexities associated with mechanical aeration and circulation including the need for electrical power and pumps which are required in many conventional hydroponic systems. Eliminating the need for electricity makes this technique most appropriate for areas where energy costs are high, or electricity is unreliable.

The suspended pot method of non-circulating hydroponics presented in this document is a powerful technique especially for growing short-term vegetables, such as lettuce, because the entire crop can be grown with only the initial application of water and nutrients. Very little labour is required, and once planted the crop can be left to grow with minimal supervision and no additional watering.

A schematic drawing of a suspended-pot, non-circulating hydroponic system.

Fig. 1: A schematic drawing of a suspended-pot, non-circulating hydroponic system.

In the most basic sense, the farmer fills a plastic tank with water, adds the correct amount of fertilizer, and seeds or transplants the plant into a tapered plastic container (ideally, net pots or forestry tubes with additional holes in their sidewalls). These are inserted directly into the container lid, or the mouth of a bottle. As the plant grows the water level falls, providing a humid zone. This moist air space provides an area for the roots to exchange gasses (oxygen and carbon dioxide) and prevents “wet feet” and other problems associated with water logged roots. No additional water or fertilizer are needed for small vegetables, and only a small amount needs to be added for the larger fruiting vegetables. The crop is normally terminated when most of the nutrient solution is consumed.

Hobby gardeners can use this method to grow short-term plants in areas such as balconies, porches, and under the overhangs of buildings. Researchers and farmers may use the hydroponic kit to conduct nutritional studies, test pesticides, and produce seed. Educators may use this method to teach students about plant growth concepts, because the materials are inexpensive and readily available and weekend watering is not necessary. Small-scale farmers can use this method to produce vegetable crops, especially in confined spaces in urban conditions.

Material needed

Short-term vegetables (e.g. lettuce)

Non circulating hydroponic system to grow salad greens in small drink containers

Fig. 2: Non circulating hydroponic system to grow salad greens in small drink containers

  • Plastic container (1 gallon or 3.8 litres) with 1½ inch (3.8 cm) opening, often a water or milk bottle
  • Complete hydroponic fertilizer (see section below)
  • Net pot 1½ inch (3.8 cm) diameter x 3 inches (7.62 cm) long, which can be substituted with a plastic cup with holes in it
  • Growing medium (may contain at least two of the following: peat, perlite, vermiculite, coconut coir) or rockwool cubes – enough to fill netpot
  • Seed of the short-term crop (such as lettuce or kai choy)
  • pH test strips
  • Phosphoric acid (available from agricultural supply shops or online) to lower the pH

Long-term vegetables (e.g. cucumber)

Non-circulating hydroponic system to grow long term vegetables.

Fig. 3: Non-circulating hydroponic system to grow long term vegetables.

  • Plastic container of 25­–40 gallons (100–150 litres), with lid. Container should have a minimum height of 10 cm for leafy vegetables and 20 cm for larger fruiting vegetables
  • Complete hydroponic fertilizer (see section below)
  • Net pot (1½-inch (3.8 cm) diameter, which can be substituted with a plastic cup with holes in it
  • Growing medium to fill the forestry tube (may contain two of the following: peat, perlite, vermiculite, coconut coir) or rockwool cubes
  • Seed of the long-term crop (such as cucumber or tomato)
  • Electric drill with ¼ -inch (0.635 cm) bit and 1½-inch (3.81 cm) hole saw
  • pH test strips
  • Phosphoric acid (available from agricultural supply shops or online) to lower the pH

Step-by-step description

The following step-by-step description refers to both growing short-term (a) and long-term (b) vegetables.

1. Clean the plastic tank/bottle

Rinse the plastic tank/bottle with water twice. Do not use bleach! If dish soap is used, rinse several times to remove the soap.

2. Select the right placement for the tank/bottle

Short-term vegetables (e.g. lettuce)

Place the container in a location that receives plenty of light (at least 4-6 hours of direct sunlight) but is protected from wind and rain. Good locations include under the overhang of a house, on a porch or balcony, or in a greenhouse. You may wish to paint the bottle or place a bag or foil around it to exclude light from the clear bottle. Otherwise, green algae may form in the bottle and slow the growth of the crop.

You can also place the bottles after seeding (step 6).

Long-term vegetables (e.g. cucumber)

Place the container on a level surface in a location that receives plenty of light (at least 6-8 hours of direct light) and is protected from wind. Good locations include a greenhouse, under the overhang of a house, or in a garden area. Outside areas are acceptable because cucumbers tolerate rain fairly well, and the sloping sides of the container lid prevent most of the rain from entering the container.

3. Water-Nutrient-Solution

Add the correct amount of complete hydroponic fertilizer to the container based on the instructions on the fertilizer package (refer to follow section for more details). Fill the container about 1/3rd with water, and swirl or stir to  dissolve some of the fertilizer. The nutrient solution (water plus fertilizer) will turn a cloudy, light yellow-green color. Some of the fertilizer will settle to the bottom.

Once most of the fertilizer is dissolved, fill up the rest of the container up to about 4 cm from the top with water. The nutrient solution will still appear cloudy, and some fertilizer will remain undissolved on the bottom.

Once the container is filled, adjust the pH to 6–6.5 using phosphoric acid (H3PO4), which is a relatively mild acid. It can be found in food-grade quality from hydroponic or agricultural supply stores under various trade names. Add a small amount of acid, wait for about 1 hour for the acid to react, test the pH, and then add more if necessary. Be careful when using acid and always wear proper safety equipment (gloves and eye protection).

TIP: If your tap water is known to have a high salts content (>0.2 mS), it would be best to substitute rainwater. Excessive salts in the water will concentrate as the nutrient solution is taken up, and plant growth will be adversely affected.

4. Filling the net pots / forestry tubes

Fill the tapered plastic net pots (ideally, net pots or forestry tubes with additional holes in their sidewalls, or plastic drinking cups with holes made into them) with growing medium. Tap them to help settle the growing medium, but do not pack it too tightly.


Net pots

Fig. 4: Net pots.

TIP: Forestry tubes typtsically have holes only at the bottom of the tube. Drill 6 or more 6 mm diameter holes in the sides of the forestry tube. This will allow the roots to emerge from both the bottom and the sides of the lower part of the forestry tube.

5. Insert the net pots/ forestry tubes

Short-term veggies

Place the net pot containing the growing medium into the bottle. The bottom 1-2 cm of the net pot should be immersed in the nutrient solution. If the net pot is too short to reach the water, a wick can be made of cloth or string. 

Long-term veggies

Drill a 3.8 cm diameter hole with a hole saw in the container lid about 7.6 cm from the edge. Place the forestry tube containing the growing medium into the lid. If the hole is placed in the middle of the lid, the forestry tube might not be long enough to reach the nutrient solution. Also, the edge of the lid is stronger than the middle. The bottom 1-2 cm of the net pot should be immersed in the nutrient solution. If the net pot is too short to reach the water, a wick can be made of cloth or string.

TIP: The net pots / forestry tubes should fit snugly in the tanks (top of the bottle/ lid of the container). This will help to prevent mosquitoes from entering the container, which could then become a breeding ground for mosquitoes. Use tape if necessary to ensure a snug fit

TIP: The growing medium becomes moistened by capillary action. If the growing medium remains dry, slowly add 5–10 mL of water to the growing medium in the net pot and forestry tube, respectively.

6. Seeding

Make a 0.5 cm deep hole (for short-term system) and 1 cm (for long-term system) respectively, in the moist growing medium with the blunt end of a pen. Plant 1 seed and cover it lightly with growing medium. If the growing medium is still dry, slowly add another small amount of water. The seed should germinate in 2–5 days. If the seed does not germinate, it may be of poor quality. Heat and high humidity destroy seed viability, so keep seeds in the refrigerator from the time they are purchased.

7. While growing

Short-term veggies

Leave the bottle alone for the next 5–6 weeks. Do not pull the net pot from the bottle – the roots will be damaged.

IMPORTANT: If more water needs to be added, do not add too much. Refilling the container completely will kill the plants. Only refill the bottom 1/3rd of the container, and only if necessary – it is better to harvest and start over.

Long-term veggies

After the roots have emerged from the forestry tube, do not pull the forestry tube from the lid—the roots will be damaged. The nutrient solution level will recede as the plant grows. We usually do not add more water or fertilizer to the container, because raising the nutrient solution level in a non-circulating hydroponic tank typically damages the plant. However, if the plant is not ready to harvest and the water level is too low, it is OK to refill up to the bottom 1/3rd of the container with fresh nutrient solution.

Build about a 2 meter high trellis to support the cucumber foliage. Train the cucumber vine or tomato stalk so that it clings to the trellis.

A view inside the plastic trash container showing profuse root growth. Most of the original nutrient solution has been consumed by the plant

Fig. 5: A view inside the plastic trash container showing profuse root growth. Most of the original nutrient solution has been consumed by the plant.

A vigorous cucumber plant growing in a plastic trash container.

Fig. 6: A vigorous cucumber plant growing in a plastic trash container.

8. Harvesting

Short-term veggies

After 5-6 weeks, harvest the crop. Congratulations! You have just successfully grown a crop by a hydroponic method

Long-term veggies

Harvest the cucumbers when they are ready. First harvest is generally about 50 days from seeding. The crop will be usually be terminated when most of the nutrient solution is consumed or when insect and/or disease pressure becomes excessive (usually after about 1 month of harvesting). To extend the plant life cycle and increase yield, it is optional to refill the container with fresh nutrient solution, but never refill more than 1/3rd of the container. Expect a yield of about 2.5 kg per plant.

TIP: Weed control can be achieved by placing black plastic weed-mat on the ground under the trash container. A permanent trellis system can be established because there is no need to dismantle the trellis system to cultivate the soil beneath the system (see also:

9. Cleaning/ Finishing

Remove the root mass and growing medium from the net pots or forestry tubes. Empty the remaining nutrient solution at the base of some bushes or trees. Wash the container/ bottle and the net pots / forestry tubes. You are ready start over and begin the next crop!


Hydroponic fertilizer/ Nutrient solutions


Premixed inorganic hydroponic fertilizer

There are many commercially available hydroponic fertilizers on the market. Most of them are based off the first-ever hydroponic recipe, the Hoagland solution first developed in 1938.  A recipe for Hoagland’s complete nutrient solution was presented in 1938, and has since been revised and amended by scientists and growers. Hoagland solution contains all nutrients essential for plant growth. It is available premixed under various trade names, and is sometimes referred to as “A B Solution”.

Many other brands and formulations of hydroponic fertilizers are available, and can be found at agricultural supply stores or online. Regardless of brand, the fertilizer should have a balanced NPK ratio (the ration between Nitrogen, Phosphorous and Potassium), plus trace elements of boron, manganese, zinc, molybdenum, magnesium and iron. In addition, most formulas require that you add calcium and magnesium. A few examples are as follows, but this does not imply a recommendation of these brands over any other.

-          For 100 gallons (380 litres)

o   0.40 lb (0.18 kg) of Masterblend® hydroponic fertilizer 20-18-38,

o   0.40 lb (0.18 kg) of calcium nitrate (Ca(NO3)2)

o   0.2 lb (0.09 kg) of magnesium sulfate (MgSO4)

-          For 100 gallons (380 litres)

o   1 lb (0.45 kg) of Chem-Gro® 10-8-22

o   0.25 lb (0.11 kg) of magnesium sulfate (MgSO4)

Always follow the instruction on the package! Notice from the two examples above that the exact rations will depend on the brand. All manufactures will provide you with the exact mixing instructions.


Home-mixed inorganic hydroponic fertilizer

If you want to make your mix hydroponic nutrients, use the following methodology. It is much easier to buy pre-mixed solutions (as indicated above), but mixing at home can save money and can give experienced growers more control. It is recommended to use premixed fertilizers if this is the first time you are doing hydroponics.

In the following, two ways of preparation are presented to blend the Hoagland solution using stock chemicals. The first method is simple and uses approximates adapted for the amateur without special weighing or measurement instruments, and the second method is more exact for more advanced growers.

Method A (adapted for amateurs)

The following recipe is for preparing 25 gallons of nutrient solution (ca 95 L). If you need smaller amounts please see Method B or recalculate the math (beyond the scope of this document).

  • Prepare the four stock solutions (A, B, C, D). The table below indicates the amounts of salts to be dissolved in the corresponding amount of water.
  • When ready to prepare the final solutions, dilute the latter three stock solutions (B, C, D) according to the dilution ration in the table. For example, a dilution ratio of 1:4 means diluting one part of the stock solution with 4 parts of water.
  • Add the indicated amount of each of the diluted solutions to 25 gallons of solution A. Your nutrient solution is finished and ready for the plants
  •  *Note: the four solutions cannot be stored after they are mixed, thus only mix stock solutions when fully ready to plant. Always store the stock solutions separately, otherwise chemical reactions will make them ineffective.
  •  *Note: the following instructions assume that each fertilizer is pure. If the purity is low, the concentrations would need to be adjusted, but it is beyond the scope of this article to go into detail. 


Stock name

Salt name

Amount of dry salt

Amount of water


Ammonium phosphate

2 tablespoons

(30 mL)

25 gallons

(94.6 L)

Potassium nitrate

5 tablespoons

(74 mL)

Calcium nitrate

6 tablespoons

(89 mL)

Magnesium sulfate

(Epsom salt)

5 tablespoons

(74 mL)


Stock name

Salt name

Salt volume

Amount of Water

Dilution ratio

Amount of diluted solution for 25 gallons final solution


Boric acid

3 teaspoons

(15 mL)

1 gallon

(3.8 L)


1 pint

(473 mL)

Manganese chloride

1 teaspoons

(5 mL)


Zinc sulfate

4 teaspoons

(20 mL)

1 gallon

(3.8 L)


1 teaspoon

(5 mL)

Copper sulfate

1 teaspoons

(5 mL)


Iron tartrate

1 teaspoon

(5 mL)

1 cup

(0.25 liter)


½ cup

(118 mL)

Step one of Solution preparation

Fig. 7: First step of solution preparation.

Step two of Solution preparation

Fig. 8: Second step of solution preparation.

Method B (exact terms)

The following recipe is for preparing 1 liter of nutrient solution. The use of distilled water and chemically pure salts is recommended.

  • Prepare six stock solutions (A, B, C, D, E, F). The table below indicates the amounts of salts (in grams) to be dissolved each in the one liter of water.
  • In order to obtain the full nutrient solution add the indicated volume of each stock solution to 800 mL of water, and then fill up to one liter. The table below indicates the volumes to be added.

Stock No

Salt name

Salt formula

Exact amount (g) to be dissolved in 1L of water

Volume per liter nutrient solution to add


Ammonium phosphate



1 mL


Potassium nitrate



6 mL


Calcium nitrate

Ca(NO3)2 ·4H2O


4 mL


Magnesium sulfate (Epsom salt)



2 mL


Boric acid



1 mL

Manganese chloride

MnCl2 ·4H2O


Zinc sulfate

ZnSO4 ·7H2O


Copper sulfate

CuSO4 ·5H2O


Molybdic acid (assaying 85% MoO3)

H2MoO4 ·H2O






1 mL (1-2 x week)


Commercial fertilizers are also available based on organic ingredients. Alternatively, you can prepare you own from compost leachate. A few general methods are provided below, but it will require trial and error based on your exact compost composition.

Make compost using your preferred technique, and refer to the following TECA articles for more information. See TECA-Technology “Compost to improve soil fertility in Dominica”

When the organic waste has finally decomposed into humus, which can take 4–6  months, it is possible to make compost tea. The process is simple. Several large handfuls of compost are tied within a mesh bag, weighted with some stones. This bag is suspended in a bucket of water (20  litres). An air stone connected to a small air pump is positioned underneath the mesh bag so that the bubbles agitate the contents. The aeration is very important to prevent anaerobic fermentation from occurring. The mixture is left for several days with constant aeration. The contents should be stirred occasionally to prevent any anoxic areas. After 2–3 days, the compost tea is ready to be used in the unit. The tea should be strained through a fine cloth and then diluted approx. 1:10 (depending on initial compost composition) with water and used as the fertilizer solution.

Using organic fertilizers can lead to anoxic conditions in the nutrient solution in the container. If available, a small aerator (air pump with an air stone) could supply air into the nutrient solution and remove this problem. However, if electricity is expensive or unavailable, it is OK to use organic fertilizers but accept that there may be bad odours and it will not be as efficient or easy as using inorganic fertilizers.

 Fig. 9: A small aerator (air pump with an air stone) to supply air into the nutrient solution.

Insects and Diseases

Mosquitoes can breed in non-circulating nutrient solution and become both a health menace and a nuisance to workers. Following are some possible mosquito control methods.

  • If plant containers are placed in a greenhouse, the sides of the greenhouse can be screened to prevent mosquitoes access.
  • Window screen may be placed in the tank below the initial nutrient solution level. Roots will extend through the screen as the crop grows. When the nutrient solution level drops below the screen, newly hatched mosquitoes under the screen are trapped.
  • Prentox® Pyronyl™ Crop Spray is currently registered for use with hydroponically-grown vegetables to control mosquito larvae in the nutrient solution. Asian tiger mosquito larvae were killed within 36 hours by 1 ppm of the commercial formulation of Pyronyl (Furutani et al. 2005). Pyronyl could also be sprayed under the elevated tanks to control adult mosquitoes which frequently hide there.

For other pests and diseases, treat as normal. It is recommended to use the integrated pest management techniques where chemical pesticide application is a last resort.

Refer to for  organic pest management tactics. Also refer to for more information on some plant-derived insecticides, beneficial insects and fungal treatments (specific for aquaponics, but applicable to all plants).


  • Vegetable crop production with low inputs and low labour
  • No electricity (no pumps) is needed
  • High resource efficiency (Water and fertilizer consumption is minimized in closed hydroponic systems) because there is no runoff and minimal evaporation.
  • Profitable for small holder farmers in urban zones with no access to land and/or poor soil fertility
  • Profitable in areas with high flood risk (systems are mobile)
  • Avoiding soil diseases, nematodes and weeds
  • Minimal labour required. There is no need to work the soil to weed, plow or till. Once the system is set up, there is no further watering. Systems can be left alone and checked on only periodically.
  • No soil required, so can be used in locations where soil is infertile, polluted or inundated with salt.



Small-scale use

The practices in this article are most appropriate for small-scale use. However, these techniques have been adapted and expanded for commercial use, and the general concept is suitable. This document only shows the small-scale use, and the targeted users are family farmers, hobbyists, educational institutions, and researchers. Households can use this method to supplement their diet of fresh vegetables.

Ground water quality

High sodium concentrations in groundwater will negatively affect plant growth because excessive salts in the water will concentrate as the nutrient solution is consumed. For this reason, a good water quality is required.

In most locations, tap water is suitable. In Gaza, where a similar technology was tested, relatively good groundwater quality was found in the North Gaza and Gaza governorates.

If there is poor water quality, it would be best to substitute rainwater because methods to pre-treat water or integrate filtered water to increase quality are often very expensive.

This technology contributes to the SDGs:


Further reading

D.R. Hoagland and D.I. Arnon. The water-culture method of growing plants without soil. Calif. Agr. Expt. Sta. Circ. 347. 1950

Quaik et al. 2012, Effect of Vermiwash and Vermicomposting Leachate in Hydroponics Culture of Indian Borage (Plectranthus ambionicus) Plantlets.
Quaik et al. 2012, Potential of Vermicomposting Leachate as Organic Foliar Fertilizer and Nutrient Solution in Hydroponic Culture: A Review.

Jarecki et al. 2005: Evaluation of Compost Leachates for Plant Growth in Hydroponic Culture.

Haghighi, M., Barzegar, M.R. & da Silva, J.A.T. Int J Recycl Org Waste Agricult (2016) 5: 231.,

Bradley K. Fox et al., Beneficial Use of Vermicompost in Aquaponic Vegetable Production, Hānai‘Ai / The Food Provider, December 2011 / January - February 2012


Created date

Tue, 29/11/2016 - 15:55


College of Tropical Agriculture and Human Resources (CTAHR), University of Hawaii at Manoa

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Fisheries and Aquaculture Department (FI) in FAO

Fisheries and aquaculture have the capacity – if supported and developed in a regulated and environmentally sensitive manner – to contribute significantly to improving the well-being of poor and disadvantaged communities in developing countries and to achievement of several of the Millennium Development Goals, especially those related to poverty reduction and food and nutrition security, environmental protection and biodiversity. As part of a long-term strategy, the FAO Fisheries and Aquaculture Department (FI) is envisioning a world in which responsible and sustainable use of fisheries and aquaculture resources makes an appreciable contribution to human well-being, food security and poverty alleviation. In this regard, FI works towards strengthening global governance and the managerial and technical capacities of members and to lead consensus-building towards improved conservation and utilization of aquatic resources. The activities of FI reflect the main FAO mandate of managing knowledge and information, assuring a global neutral forum for Members and providing technical assistance at national, regional and global levels.

In addition, the FAO Fisheries and Aquaculture Department undertakes capacity development activities for marine and inland fisheries as well as aquaculture. These include training at different levels, preparation of training and extension materials for general or targeted training, awareness raising through workshops, and collaboration with partner training institutions.  The FI is also involved in the development of appropriate technical guidelines and the promotion of participatory approaches in sustainable and responsible aquatic resources management, including gender aspects.

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