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HS510

Grow Your Own Vegetables Without Soil1

James M. Stephens2

1. This document is HS510, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date March 1994. Reviewed May 2003. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2. James M. Stephens, professor, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean

Growing plants without soil is often called hydroponics. The name implies that the plants are grown in water containing dissolved nutrients. However, pure water culture is only one of the many methods employed. All of the other methods might simply be grouped as "soilless" culture, which would include sand culture, gravel culture, and culture utilizing other soil substitutes such as sawdust, wood shavings and vermiculite.

The information reported here in "Grow Your Own Vegetables Without Soil" should be beneficial to the gardening enthusiast who wishes to try hydroponics as a hobby. The commercial production of vegetables utilizing hydroponic techniques is complicated and should be employed by only the most competent grower. Commercial growers should refer to Florida Cooperative Extension Service Bulletins specifically developed for the hydroponic industry.

How Water Culture Works

In water culture, plants are grown with roots submerged in a nutrient solution, with the stem and upper parts of the plants held above the solution. With this system, the main considerations are: provision of a suitable container, suspension of the plants above

the water, provision of a suitable nutrient solution, and proper aeration of the water solution.

Containers For Water Culture

There are many kinds of containers that might be used — a cement trough, glass jars, earthenware crocks, metal containers, or fiberglass tank. Of course, these all must be leak proof. Glass containers should be painted dark on the outside to keep sunlight from making chemical changes in the solution and to prevent the growth of algae. Leave an unpainted narrow strip down the side so the level of the solution can be checked. Metal and concrete containers should be painted inside with asphalt emulsion to prevent corrosion and toxicity to the plants. Fiberglass is more resistant to corrosion than the other materials.

Supporting The Plants

A "platform" for planting into and supporting the

plants as they grow will be needed. This is sometimes called the "litter bearer." It is often made of chicken wire or hardware cloth (wire) base on which is placed about three inches of wood shavings, excelsior or similar material called litter. The metal wire should be constructed to fit across the top of the container and should be plastic covered or painted

Kidsgardening.org

Exploring Classroom Hydroponics

http://www.kidsgardening.com/hydroponicsguide/hydro8-1-resources.asp

Growing Edge http://www.growingedge.com/basics/tutorial/01_history.html

S.H.A.R.P. Lesson Plans for Hydroponics http://library.thinkquest.org/C0110342/lessonplan

Verti-gro Systems

http://vertigro.com/

Hydro-stacker Systems

http://www.hydrostacker.com/

Resources:


http://www.growingedge.com/basics/tutorial/01_history.html


http://library.thinkquest.org/C0110342/lessonplan





Grow Your Own Vegetables Without Soil 2

with asphalt-based paint. The platform and supporting material need to be porous to allow for aeration.

Styrofoam has also been suggested as a means of stabilizing the plants above the solution. Plants are inserted into holes in the floating styrofoam. Holes should be large enough to avoid constriction of stems at maturity. Cotton or other material may be used as shims in the holes around the stems. Punch holes at random in the styrofoam to allow for better aeration. The tops of heavy or cumbersome plants need to be further supporting by trellising.

Aeration

For young plants, leave about one inch of air space between the litter and the solution. As plants grow, allow 2 or 3 inches of air space below the litter. Lack of oxygen in the water and resulting growth impairment may occur unless air is pumped through the solution with a pump, compressed air or other equipment. Bubbles should be spaced 1/2 to 1 inch apart as they rise through the solution. Aerators normally used to keep fish alive in bait wells or aquariums are suitable for small units.

Nutrient Solution For Water Culture

There is no one ideal nutrient solution. Any good solution will contain all of the essential elemental nutrients needed for plant growth. The sources and amounts of these nutrients will vary from on suggested solution to another, but are commonly available as commercial fertilizer and chemically-pure salts. Along with the many formulas suggested, there is a variety of ready to use solutions on the market. Most all of these combinations give fair to excellent results when used as directed and are suggested for hydroponic hobbyists. These mixes are easily dissolved in water for a proper nutrient solution.

With any solution, the composition changes as the plants grow and utilize the nutrients. Therefore, care and attention must be given to controlling the content, either by additions of certain ingredients as needed, or by changing the solution completely from time to time. Since frequent testing is necessary to determine which nutrients have gotten out of balance,

it is easier to change the solution. Table 1 gives a popular formula for general plant production. Some elements are required in very small or trace amounts and must be added to the forumula given in Table 1. The formula in Table 2 will provide a satisfactory solution for this purpose.

Using the Solution in Water Culture

In a small setup, the nutrient solution can be mixed in small containers and added as needed. At the beginning, the container is filled with solution almost to the level of the litter. Then, at predetermined intervals, the old solution is thrown out and new solution added. The frequency and number of changes of the solution will depend on the size of the plants, how fast they are growing, and the size of the container. Just as a starting point for beginners, solution changes might be made at weekly intervals for the first few weeks, then twice weekly for older plants. Should the water level get too low between changes, add only water until time to change solutions.

Adjustment of the acidity or alkalinity (measured as pH) of the water may be necessary to keep it within an adequate plant growing range of pH 6.0-6.5. This means testing with indicator paper and adding sulfuric acid, if needed, to lower pH or an alkaline material such as sodium hydroxide to raise pH.

Nutrient Flow Technique (NFT)

Many commercial systems today utilize a series of plastic tubing through which a nutrient solution is circulated around the roots of vegetables inserted into the tube. This modern system is called the nutrient-flow technique (NFT).

For NFT, two types of tubing are most often used: 1) black polyethylene film folded and stapled to form a 6-8 inch wide channel; and 2) PVC pipe (4-6 inch diameter). In both cases, plant holes are spaced at proper intervals along the tubing. Nutrient flow can be a continuous or intermittent recirculation of a nutrient solution from a supply tank.


Aggregate Culture

Gravel is sometimes used by commercial operators in Florida. However, gravel is only one example of a solid material substitute for soil or water. The use of such solid media is generally referred to as aggregate culture. This technique has good possibilities for home gardeners as well.

Crops are grown in shallow tanks or troughs that serve as the container for the gravel. The gravel, sand or other aggregates are used much as soil is used in conventional plantings — to provide anchorage and support for the plants. Nutrients can be supplied in solution form or as dry fertilizer in any one of several fashions: 1) flooded from the bottom up; 2) drenched on the surface; 3) trickled onto the surface; or 4) scattered dry on the surface and watered into the root zone. Whenever it is to be applied from the bottom, fairly coarse materials such as gravel should be used so that the medium will flood and drain easily. Sand usually is not coarse enough for bottom feeding, but works well with top feeding.

For single rows of tomatoes, beds 24 to 36 inches wide are adequate. Usually, it is made of plastic-lined wood, fiberglass, plastic or poured concrete with sides about 8 inches high and with a V bottom so the center is 12 inches deep. If concrete is not lined, the inside should be painted to prevent chemical injury from the concrete and chemicals reacting. Thus, a half-tile or similar device through the center of the bed will feed or drain the solution rapidly from one end of the bed to the other. At one end of the trough there must be a pipe connection to the lowest point in the V with a little slope toward that end. The slope should be precise, without low areas to impede drainage. The nutrient solution can be pumped into the trough through that pipe and to within one inch of the surface and then drained out again when the pump is shut off. Such flooding and drainage should be accomplished within a 10-30 minute period, and at intervals of 1, 2 or more times daily. By personal inspection, it can be determined how often applications are needed to maintain adequate moisture in the root zone.

Some combinations of aggregate materials other than gravel which have been tried successfully with

tomatoes are as follows: 1) sand; 2) 1 part sand to 1 part vermiculite; 3) 1 part sand to 1 part rice hulls; 4) 1 sand to 1 redwood bark; 5) 1 sand to 1 pine bark; 6) 1 sand to 1 peat moss; 7) 1 sand to 1 perlite; and 8) 1 or 2 sand to 1 peat moss. In most cases, sand alone has been as satisfactory as sand mixed with other materials. Sawdust and wood shavings are also acceptable. More recently, a fibrous stone material called "rockwool" has become increasingly popular.

Nutrient Solutions For Aggregate Culture

With aggregate culture, the same nutrient solution as prepared for water culture may be used. Various techniques might be used to apply the solution the plants. For larger troughs, a pump is often used to fill the trough to within an inch of the top. When the pump is shut off, the liquid solution drains back into the supply tank, leaving the aggregate medium moist. A time clock may be used to start and stop the pump at selected intervals.

For small units, a simple system consists of a 5- gallon bucket of solution supported by a pulley and attached by a hose to the aggregate tank. At feeding time, the bucket is raised above the height of the tank so the solution will flow by gravity into the medium. Then, when lowered the excess solution drains back into the bucket. This feeding technique is best suited to porous aggregate such as gravel; some difficulty might be experienced where organics such as peat are included.

With organic mixes, and for very small containers such as cans, buckets and hampers, solutions could be sloshed by hand on top of the aggregate medium. This should be done at the required intervals. Excess solution merely drains away through holes in the bottom of the containers and does not involve recirculation. The nutrient solution can also be delivered to each individual container by a dripline or spaghetti tube, as is commonly done with bag culture.

Prepared Mixes

A rather popular technique is to use commercial grade fertilizer to pre-mix nutrients into the aggregate just as the medium is being prepared. One popular mix is the Cornell Peatlite Mix, listed in Table 3 for the preparation of one cubic yard of mix.


As the plants grow in the prepared mix, it is necessary to add more nutrients from time to time. Again, any one of several preparations could be utilized satisfactorily for this purpose, but one of the easiest to prepare solutions results from the use of commercially available soluble fertilizer. Two suggested solutions for weekly feedings are made with 20-20-20 analysis fertilizer at 1 pound per 100 gallons and 25-5-20 at 1 pound per 100 gallons. A suggested schedule for their use would be to use the 20-20-20 for the first three weeks, followed by 25-5-20 the rest of the way. Where tomatoes are the primary crop, substitute 2 pounds of calcium nitrate (per 100 gallons water) for the complete fertilizer. This should be done about every two weeks to insure adequate calcium and reduce blossom-end rot.

Amateurs Only

Please keep in mind that this guide is for use by hobby hydroponics enthusiasts only. Commercial production of vegetables using soilless culture is a capital-intensive, complicated, and high management- intensive enterprise. A commercial producer should seek advice from the county agricultural agent and literature written specifically for the hydroponics industry.


Table 1. Formula for preparing a general purpose nurient solution (Hoagland).

Amount for 25 gallons of solution

Salt Grade Nutrient Oz. Level tbsp.

K phos.(mono-basic) Technical Potassium, Phosphorus 1/2 1

K nit. Fertilizer Potassium, Nitrogen 2 4

Ca nit. Fertilizer Calcium, Nitrogen 3 7

Mg sulf. Technical Magnesium, Sulfur 1 1/2 4

Table 2. Formula for solution providing trace elements.

Salt (Chemical Grade) Nutrients Amount water to add to 1 level tsp salt

Amount to use for 25 gal. solution

Boric acid, powdered Boron 1/2 gal. 1/2 pintManganese chloride (MnCl

24H

2O) MnCl 1 1/2 gals. 1/2 pint

Zinc sulfate (ZnSO47H

2O) Zinc Sulfur 2 1/2 qts. 1/2 tsp.

Copper Sulfate (CuSO45H

2O) Copper Sulfur 1 gal. 1/5 tsp.

Iron tartrate (chelated Fe330) Iron 1 qt. 1/2 cup

Mo trioxide (MoO3) Molybdenum 1 qt. 1 oz.

Table 3. Cornell Peatlite Mix

Material Amount

Shredded sphagnum peat moss 11 bushels

Horticultural vermiculite 11 bushels

Dolomite 12 pounds

Calcium sulfate (gypsum) 5 pounds

Superphosphate 2 pounds 20%Calcium or potassium nitrate 1 1/2 pounds

Iron (chelated Fe330) 1 ounce

Fritted Trace Elements 6 ounces

HS796

Nutrient Solution Formulation for Hydroponic (Perlite, Rockwool, NFT) Tomatoes in Florida1

George J. Hochmuth and Robert C. Hochmuth2

1. This document is HS796, one of a series of the Department of Horticultural Sciences, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: October, 1990 as SSVEC44. Revision date: August 2001. Reviewed November 2008. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.

2. George J. Hochmuth, associate dean for research and associate director, Florida Agricultural Experiment Station, Robert C. Hochmuth, agent IV, North Florida Research and Education Center - Suwannee Valley, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean

Plants require 16 elements for growth and these nutrients can be supplied from air, water, and fertilizers. The 16 elements are carbon (C), hydrogen (H), oxygen (O), phosphorus (P), potassium (K), nitrogen (N), sulfur (S), calcium (Ca), iron (Fe), magnesium (Mg), boron (B), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), and chlorine (Cl). The key to successful management of a fertilizer program is to ensure adequate concentrations of all nutrients throughout the life cycle of the crop. Inadequate or excessive amounts of any nutrient result in poor crop performance. Excessive amounts can be especially troublesome since they can damage the crop, waste money and fertilizer resources, and pollute the environment when fertilizer is released during flushing of the nutrient delivery system.

For Florida greenhouse vegetable producers, management focuses on all nutrients except for C, H, and O. The latter three elements are usually supplied in adequate amounts from air and water. Growers in northern climates, where greenhouses are not ventilated in the winter, see benefits from additions of C from carbon dioxide (CO

2). Increased yields in

Florida from additions of CO2 are unlikely due to the

need for frequent ventilation.

Crop demand for nutrients changes through the season. Small amounts of nutrients are needed early, then the demand increases as the crop grows, especially after several clusters of fruit have been set on the plant. A common problem comes early in the season when plants become too vegetative (bullish) from too much N. The bullish growth distorts the leaves and stems, causing cracks and grooves in the stems. These openings are excellent entry ports for decay-causing organisms such as soft rot. Bullish plants usually produce misshapen fruits often with significant amounts of blossom-end rot and cat-facing. Keeping the N level low (60 to 70 parts per million) early in the season helps eliminate bullishness.

High K also can be a problem since it can interfere with the plant's capability to absorb Ca and Mg. Plants exposed to excess K often develop Mg deficiency on the lower leaves and the fruits often develop blossom-end rot (BER), especially early in the season.

Nutrient Solution Formulation for Hydroponic (Perlite, Rockwool, NFT) Tomatoes in Florida 2

Nutrient management programs should begin with an understanding of the nutrient solution concentrations in parts per million (ppm) for the various nutrients required by tomato plants. By managing the concentrations of individual nutrients, growers can control the growth and yield of the crop. Table 1 presents the fertilizer recommendations for tomatoes for the various growth stages during the season in Florida. These recommendations are applicable to all types of production systems (perlite, rockwool, and NFT) in which healthy roots are maintained, and are a suitable base when determining a nutrient solution plan for cucumbers and peppers. However, cucumbers will need more N early in the season than tomato.

The major elements to manage are N and K for the reasons cited above. The program outlined in Table 1 has been proven in Florida and should provide adequate nutrition and avoid the problems of bullishness as well as the problems of fruit ripening disorders indirectly caused by excess K. Final solution pH should be in the range of 5.8 to 6.2.

One of the first steps in a nutrient management program is to test the well water. A water sample should be analyzed for pH, carbonates, S, Mg, Ca, and Fe. Most well water in Florida has pH greather than 6.5. The pH and carbonates are used to guide in the acidification of the nutrient solution. Water from many wells in Florida contains significant amounts of Ca and often small amounts of Mg. Growers can take advantage of these nutrients, which in the case of Ca, might be 40 to 60 ppm. Some, but probably not all of this Ca is available to the crop.

Sulfur and iron concentrations are determined because they can increase potential for irrigation emitter clogging from bacterial slimes that use the Fe and S for growth. These nutrients generally are not considered in the nutrient formulation calculations.

Formulation Methods

There are basically two methods to supply the fertilizer nutrients to the crop: 1) premixed products, or 2) grower-formulated solutions. The two methods differ in the approach to formulating the fertilizer and the resulting nutrient-use efficiency. Fertilizer materials that can be used for both methods are

presented in Table 2. The formulae in this publication are for a final dilution of 1 gallon each stock to 100 gallons of final solution. If using proportioners installed in parallel on one water source line, amounts of fertilizers in stocks will need to be calculated keeping in mind the intended final concentrations.

Pre-Mix Method

There are several commercial pre-mixed fertilizer formulations and some of these generalized formulations are presented in Table 2. Some of these materials contain Mg, some do not. Those that do not will need to be supplemented with magnesium sulfate. All formulations need supplementing with Ca (from calcium nitrate or calcium chloride) and N (from several possible sources). Formulations using these premixed materials that approximate the recommended program are presented in Table 3. In Table 3, the amount of pre-mixed material was chosen to provide adequate P since the pre-mixed material is the only source of P. The pre-mixed materials contain large amounts of K making it difficult to achieve the desired K and Ca concentrations. This could cause an early problem with BER when there is excess K coming from the A stock and a low Ca concentration in the well water (below 50 ppm) because K can interfere with Ca uptake by the root. This problem is common to all pre-mixed formulae. More Ca can be supplied from calcium chloride but it would be better to have lower K concentrations. A related problem is that some of the pre-mixed formulae have too much N in the formulation to allow for providing adequate Ca by adding calcium nitrate. An option to increase the Ca in the solution is to supplement the calcium nitrate stock with calcium chloride. Each pound of calcium chloride (36% Ca) in 30 gallons of stock solution results in a 14 ppm increase in Ca in the final nutrient solution delivered to the plants. The pre-mixed materials come fairly close to providing the desired concentrations of micronutrients, although some are higher than needed in Florida.

Formulation Recipe Method

Information on formulating fertilizer solutions from individual ingredients is presented in Tables 4 and 5. Four formulae are presented to provide options for formulating nutrient solutions depending


on grower preference. Formula 1 uses phosphoric acid to provide P and to simultaneously partially acidify the nutrient solution. Additional acidification might be required for some water and this can be accomplished with sulfuric acid. This formula also uses potassium chloride to provide K. There is no problem with using potassium chloride as a partial source of K. It provides K in the same form as potassium nitrate and potassium chloride is less expensive. The chloride ion is not toxic to plants in these amounts provided and some research shows that it contributes to fewer fruits with soft rot. Only greenhouse soluble-grade potassium chloride should be used. Formula 1 also uses individual chemicals to provide the micronutrients.

Formula 2 is a variation of formula 1, however, formula 2 uses a pre-mixed micronutrient package, S.T.E.M. (soluble trace element mixture), to supply most of the micronutrients. However, S.T.E.M. does not, alone, provide enough B, Fe, or Mo, so these are supplemented from individual ingredients.

Formula 3 uses monopotassium phosphate to provide the P and some K. Monopotassium phosphate is the most common source of P in the commercial pre-mixed materials. Acidification of the nutrient solution should be accomplished by another acid such as sulfuric acid. Formula 3 also uses potassium chloride and provides the micronutrients from individual ingredients.

Formula 4 uses potassium nitrate to supply all of the K. One potential problem in this formula is that large amounts of N are also supplied with the potassium nitrate and this restricts the amounts of calcium nitrate that can be added. Reducing the calcium nitrate too far might lead to BER unless the well water is supplying some Ca. Supplying some of the K from potassium chloride will allow room for more calcium nitrate.

Products for the formula method are easily obtainable in Florida and this method should result in considerable financial savings, especially for large growers. There is a small amount of extra effort involved in the formula method due to the extra measuring. The resulting higher degree of control over the nutrient supply to the crop should more than pay back any increased effort.

Water-Fertilization Relationship

The nutrient solution formulations presented in this publication were designed for production systems using hydroponic approaches to tomato culture. The media discussed in this publication (perlite, rockwool or NFT) require frequent irrigations during the day, ranging from 10 to 20 cycles per day, depending on the weather and greenhouse environment, in order to maintain about 20% solution leach. It is impossible to have an exact formulation that will work for every production system under any environmental conditions. For example, when using a media of high water-holding capacity, fewer irrigation cycles will be needed during the day. In this situation, the nutrient concentrations in the irrigation water might need to be greater than those presented in this publication so that adequate nutrition is supplied. A general rule-of-thumb is that nutrient concentrations need to be greater in production systems requiring fewer irrigations, compared to systems requiring more frequent irrigations.


Table 1. Fertilizer recommendations for hydroponic (perlite, rockwool, and NFT) tomatoes in Florida.

Stage of growth

1 2 3 4 5

Nutrient

Transplant to 1st cluster

1st cluster to 2nd cluster

2nd cluster to 3rd cluster

3rd cluster to 5th cluster

5th cluster totermination

--------------- Final delivered nutrient solution concentration (ppm)z --------------

N 70 80 100 120 150

P 50 50 50 50 50

K 120 120 150 150 200

Ca 150 150 150 150 150

Mg 40 40 40 50 50

S 50 50 50 60 60

Fe 2.8 2.8 2.8 2.8 2.8

Cu 0.2 0.2 0.2 0.2 0.2

Mn 0.8 0.8 0.8 0.8 0.8

Zn 0.3 0.3 0.3 0.3 0.3

B 0.7 0.7 0.7 0.7 0.7

Mo 0.05 0.05 0.05 0.05 0.05

NOTE: Ca, Mg, and S concentrations may vary depending on Ca and Mg concentration in wellwater and amount of sulfuric acid used for acidification.z 1ppm = 1mg/liter

Table 2. Pre-mixed and individual-salt fertilizer materials for use in hydroponic nutrient solution formulations.

Selected Pre-mixed Materialsz

Nutrient Pre-mix 14-18-38

%

Pre-mix 23-15-27

%

Pre-mix 35-11-26

%

Pre-mix 47-17-37

%

N 4 3 5 7

P

2O

5 (P) 18 (7.7) 15 (6.5) 11 (4.7) 17 (7.3)

K2O (K) 38 (32) 27 (22) 26 (22) 37 (31)

Mg 0 5.32 0 0

Fe 0.4 0.45 0.31 0.40

Mn 0.2 0.057 0.05 0.10

Zn 0.05 0.034 0.016 0.02


Table 2. Pre-mixed and individual-salt fertilizer materials for use in hydroponic nutrient solution formulations.

Cu 0.05 0.011 0.016 0.01

B 0.20 0.170 0.05 0.18

Mo 0.01 0.011 0.01 0.01

Individual Ingredientsy

Ammonium nitrate (NH4NO

3) 33.5% N

Calcium nitrate liquid (7-0-0-11) 12.1 lb/gal (Ca(NO3)2) 7%N, 11% Ca

Calcium nitrate (Ca(NO3)2)-dry 15% N, 19% Ca

Calcium chloride (CaCl2) 36% Ca

Potassium nitrate (KNO3) 13% N, 36.5 K

Monopotassium phosphate (KH2PO

4) 23% P, 28% K

Phosphoric acid (H3PO

4) 13 lb./gal. 23% P

Potassium chloride (KCl) - greenhouse 51% K

Magnesium sulfate (MgSO4) 10% Mg, 14% S

Solubor 20.5% B

Copper sulfate (CuSO4) 25% Cu

Zinc sulfate (ZnSO4) 36% Zn

Iron, Fe 330 chelated iron, etc. 10% Fe

Manganous sulfate (MnSO4) 28% Mn

Sodium molybdate (Na2(Mo)

4) (liquid), (11.4 lb/gal) 17% Mo

Sodium molybdate (dry) Na2(MoO

4) 39.6 % Mo

Soluble Trace Element Mixture (S.T.E.M.): 1.35% B

7.5% Fe

8.0% Mn

0.04% Mo

4.5% Zn

3.2 % Cu

Convert K2O to K by multiplying by 0.83. Convert P

2O

5 to P by multiplying by 0.44.

z Mention of a trade name does not constitute an endorsement or recommendation.

yExact nutrient concentration of the fertilizer material may vary depending on commercial source.


Table 3. Examples of formulations using pre-mixed commercial materials.

Stage of growth

1 2 3 4 5

Transplant to 1st

cluster set 1st cluster to 2nd cluster



5th cluster to termination

---------------------------Pre-mix 1 (4-18-38)------------------------

1 2 3 4 5

A Stock 16 lb. Pre-mix 110 lb. MgSO

4

16 lb. Pre-mix 110 lb. MgSO

4


4


4


4

B Stock 7.5 lb. Ca(NO3)2

9.5 lb. Ca(NO3)2

12.0 lb. Ca(NO3)2

16.5 lb. Ca(NO3)2

20.5 lb. Ca(NO3)2

-------------------------final concentrations (ppm)-------------------

N 70 82 100 124 148

P 49 49 49 49 49

K 200 200 200 200 200

Ca 56 71 94 124 154

Mg 40 40 40 48 48

S 50 50 50 60 60

Fe 2.5 2.5 2.5 2.5 2.5

Cu 0.3 0.3 0.3 0.3 0.3

Mn 1.3 1.3 1.3 1.3 1.3

Zn 0.3 0.3 0.3 0.3 0.3

B 1.3 1.3 1.3 1.3 1.3

Mo 0.06 0.06 0.06 0.06 0.06

----------------------------------Pre-mix 2 (3-15-27)---------------------------

A Stock 20 lb Pre-mix 2 20 lb Pre-mix 2 20 lb Pre-mix 2 20 lb Pre-mix 22 lb MgSO

4

20 lb Pre-mix 22 lb MgSO

4

B Stock 7.5 lb Ca(NO3)2

9.2 lb Ca(NO3)2

12. 4 lb Ca(NO3)2

15.7 lb Ca(NO3)2

19 lb Ca(NO3)2

2 lb KNO3

-------------------------final concentrations (ppm)---------------------------

N 70 80 100 120 150

P 51 51 51 51 51

K 178 178 178 178 208

Ca 57 69 93 118 143

Mg 42 42 42 50 50



S (est.) 50 50 50 60 60

Fe 3.6 3.6 3.6 3.6 3.6

Cu 0.09 0.09 0.09 0.09 0.09

Mn 0.45 0.45 0.45 0.45 0.45

Zn 0.27 0.27 0.27 0.27 0.27

B 1.35 1.35 1.35 1.35 1.35

Mo 0.09 0.09 0.09 0.09 0.09

--------------------------Pre-mix 3 (5-11-26)----------------------------

1 2 3 4 5

A Stock 27 lb Pre-mix 310 lb. MgSO

4

27 lb Pre-mix 310 lb. MgSO

4


4


4


4

B Stock 2.8 lb Ca(NO3)2

4.4 lb Ca(NO3)2

7.7 lb Ca(NO3)2

11 lb Ca(NO3)2

16 lb Ca(NO3)2

----------------------final concentrations (ppm)----------------------

N 70 80 100 120 150

P 51 51 51 51 51

K 232 232 232 232 232

Ca 21 33 58 83 120

Mg 40 40 40 50 50

S 50 50 50 60 60

Fe 3.3 3.3 3.3 3.3 3.3

Cu 0.17 0.17 0.17 0.17 0.17

Mn 0.55 0.55 0.55 0.55 0.55

Zn 0.17 0.17 0.17 0.17 0.17

B 0.55 0.55 0.55 0.55 0.55

Mo 0.11 0.11 0.11 0.11 0.11

-----------------------Pre-mix 4 (7-17-37)-----------------------

1 2 3 4 5

A Stock 17 lb. Pre-mix 410 lb. MgSO

4


4


4


4


4

B Stock 4 lb. Ca(NO3)2

6 lb. Ca(NO3)2

9 lb. Ca(NO3)2

12 lb. Ca(NO3)2

17 lb. Ca(NO3)2

--------------------------final concentrations (ppm)----------------------

N 71 83 101 119 149

P 49 49 49 49 49

K 208 208 208 208 208



Ca 30 45 67 89 127

Mg 40 40 40 48 48

S 50 50 50 60 60

Fe 2.7 2.7 2.7 2.7 2.7

Cu 0.07 0.07 0.07 0.07 0.07

Mn 0.67 0.67 0.67 0.67 0.67

Zn 0.14 0.14 0.14 0.14 0.14

B 1.2 1.2 1.2 1.2 1.2

Mo 0.07 0.07 0.07 0.07 0.07

NOTE: Calculations in above table are for amount of fertilizer material in 30-gal stock tanks and then for a 1:100 dilution (1 gal each stock in 100 gals final nutrient solution). Fertilizer amounts placed in each stock tank will need to be doubled if fertilizer proportioner (1:100) pumps are installed in parallel in same incoming water line.

Ca, Mg, and S values will vary upwards depending on the amount of Ca and Mg coming from the water source, and the of S coming from the sulfuric acid used for acidification.

Table 4. The following list provides the ppm of a specific nutrient provided by a specified amount of a particular fertilizer material for a 30-gal stock tank and a final dilution of 1:100.

Amount of material Material ppm nutrient provided

1 lb Potassium nitrate 5 ppm N14.5 ppm K

1 lb Ammonium nitrate 13.3 ppm N

1 lb Potassium chloride 20.3 ppm K

1 lb Magnesium sulfate 4 ppm Mg5.6 ppm S

1 pint Liquid calcium nitrate 4.2 ppm N6.6 ppm Ca

1 lb Dry calcium nitrate 6.1 ppm N7.5 ppm Ca

1 lb Calcium chloride 14.3 ppm Ca

1 quart Phosphoric acid 30 ppm P

1 gramz Solubor 0.018 ppm B

0.5 lb Fe 330 chelated iron 2.0 ppm Fe


Table 4. The following list provides the ppm of a specific nutrient provided by a specified amount of a particular fertilizer material for a 30-gal stock tank and a final dilution of 1:100.

100 grams S.T.E.M. 0.12 ppm B0.28 ppm Cu0.66 ppm Fe0.70 ppm Mn

0.0035 ppm Mo0.39 ppm Zn

1 gram Copper sulfate 0.021 ppm Cu

1 gram Manganese sulfate 0.024 ppm Mn

1 gram Zinc sulfate 0.03 ppm Zn

1 ml Liquid sodium molybdate 0.02 ppm Mo

1 gram Dry sodium molybdate 0.03 ppm Mo

1 lb Monopotassium Phosphate 9 ppm P11 ppm K

zA gram scale or laboratory pipette will be needed to measure amounts of micronutrients or to calibrate a measuring spoon set to provide the correct amount of micronutrient materials. The following are some approximate equivalences for measuring dry fertilizer materials.

Approximate weight (grams) for several measuring utensils

Fertilizer 1 teaspoon (level) 1 tablespoon (level) one dry "ounce" in measuring cup

Sequestrene Fe 330 4 14 20

Ammonium molybdate 7 - -

Sodium molybdate 4 - -

Solubor 2 6 10

S.T.E.M. 5 14 25

Manganese sulfate 6 16 30

Zinc sulfate 5 13 26

Copper sulfate 7 20 35

Table 5. Several examples of tomato nutrient solution formulations using the “formula method” with individual ingredients.

Stage of growth

1 2 3 4 5

Transplant to 1st cluster

1st cluster to 2nd cluster



5th cluster totermination

----------------------------------FORMULA 1-------------------------------



A Stock 3.3 ptsPhos. acid

3.3 ptsPhos. acid

3.3 ptsPhos acid

3.3 ptsPhos. acid

3.3 ptsPhos. acid

6 lb. KCl10 lb. MgSO

4


4


42 lb. KNO

3


42 lb. KNO

3


46 lb. KNO

31 lb. NH

4NO

3

10 gr CuSO4

35 gr MnSO4

10 gr ZnSO4

40 gr Solubor3 ml Na Moly

10 gr CuSO4

35 gr MnSO4

10 gr ZnSO4


10 gr CuSO4

35 gr MnSO4

10 gr ZnSO4


10 gr CuSO4

35 gr MnSO4

10 gr ZnSO4


10 gr CuSO4

35 gr MnSO4

10 gr ZnSO4


B Stock 2.1 gal.Ca(NO

3)2

2.4 gal.Ca(NO

3)2

2.7 gal.Ca(NO

3)2

3.3 gal.Ca(NO

3)2

3.3 gal.Ca(NO

3)2

or 11.5 lb dryCa(NO

3)2

or 13.1 lb dryCa(NO

3)2

or 14.8 lb dryCa(NO

3)2

or 18.0 lb dryCa(NO

3)2

or 18.0 lb dryCa(NO

3)2

0.7 lb Fe 330 0.7 lb Fe 330 0.7 lb Fe 330 0.7 lb Fe 330 0.7 lb Fe 330

----------------------final concentrations (ppm)------------------------

N 70 80 100 120 153

P 50 50 50 50 50

K 119 119 148 148 206

Ca 111 (86)z 127 (98) 143 (111) 174 (135) 174 (135)

Mg 40 40 40 48 48

S 56 56 56 66 66

Fe 2.8 2.8 2.8 2.8 2.8

Cu 0.2 0.2 0.2 0.2 0.2

Mn 0.8 0.8 0.8 0.8 0.8

Zn 0.3 0.3 0.3 0.3 0.3

B 0.7 0.7 0.7 0.7 0.7

Mo 0.06 0.06 0.06 0.06 0.06

---------------------------------FORMULA 2-------------------------------

A Stock 3.3 ptsPhos. acid

3.3 ptsPhos. acid

3.3 ptsPhos. acid

3.3 ptsPhos. acid

3.3 ptsPhos. acid

6 lb KCl10 lb. MgSO

4

6 lb KCl10 lb. MgSO

4

6 lb KCl10 lb. MgSO

42 lb. KNO

3

6 lb KCl12 lb. MgSO

42 lb. KNO

3

6 lb KCl12 lb. MgSO

46 lb. KNO

31 lb. NH

4NO

3

100 gr. S.T.E.M.40 gr. Solubor3 ml Na Moly







B Stock 2.1 galCa (NO

3)2

2.4 galCa (NO

3)2

2.7 galCa (NO

3)2

3.3 galCa (NO

3)2

3.3 galCa (NO

3)2

or 11.5 lb dryCa (NO

3)2


3)2


3)2


3)2


3)2


---------------------------final concentrations (ppm)--------------------------

N 70 80 100 120 150

P 50 50 50 50 50

K 119 119 148 148 206

Ca 111(86)z 127(98) 143(111) 174(135) 174(135)

Mg 40 40 40 48 48

S 56 56 56 66 66

Fe 2.7 2.7 2.7 2.7 2.7

Cu 0.28 0.28 0.28 0.28 0.28

Mn 0.7 0.7 0.7 0.7 0.7

Zn 0.39 0.39 0.39 0.39 0.39

B 0.84 0.84 0.84 0.84 0.84

Mo 0.06 0.06 0.06 0.06 0.06

---------------------------------FORMULA 3---------------------------------

A Stock 5.5 lb KH2PO

44 lb KNO

310 lb MgSO

4

5.5 lb KH2PO

44 lb KNO

310 lb MgSO

4

5.5 lb KH2PO

45 lb KNO

310 lb MgSO

41 lb KCl

5.5 lb KH2PO

48 lb KNO

312 lb MgSO

41 lb KCl

5.5 lb KH2PO

48 lb KNO

312 lb MgSO

41 lb KCl2 lb NH

4NO

3

10 gr Cu SO4

35 gr Mn SO4

10 gr Zn SO4


10 gr Cu SO4

35 gr Mn SO4

10 gr Zn SO4


10 gr Cu SO4

35 gr Mn SO4

10 gr Zn SO4


10 gr Cu SO4

35 gr Mn SO4

10 gr Zn SO4


10 gr Cu SO4

35 gr Mn SO4

10 gr Zn SO4


B Stock 1.5 galCa(NO

3)2

1.8 galCa(NO

3)2

2.2 galCa(NO

3)2

2.4 galCa(NO

3)2

2.5 galCa(NO

3)2

or 8.2 lb dryCa(NO

3)2

or 9.8 lb dryCa(NO

3)2

or 12.3 lb dryCa(NO

3)2

or 13.1 lb dryCa(NO

3)2

or 13.7 lb dryCa(NO

3)2


------------------------final concentrations (ppm)----------------------

N 70 80 100 120 150

P 50 50 50 50 50



K 119 119 153 153 196

Ca 79(61)z 94(74) 118(92) 126(98) 131(103)

Mg 40 40 40 48 48

S 56 56 56 66 66

Fe 2.8 2.8 2.8 2.8 2.8

Cu 0.2 0.2 0.2 0.2 0.2

Mn 0.8 0.8 0.8 0.8 0.8

Zn 0.3 0.3 0.3 0.3 0.3

B 0.7 0.7 0.7 0.7 0.7

Mo 0.06 0.06 0.06 0.06 0.06

----------------------------FORMULA 4----------------------------

A Stock 3.3 ptsPhos. acid8.3 lb. KNO

310 lb. MgSO

4

3.3 ptsPhos. acid8.3 lb. KNO

310 lb. MgSO

4


310 lb. MgSO

4


312 lb. MgSO

4


312 lb. MgSO

4






B Stock 6.7 pt.Ca(NO

3)2

9 pt.Ca(NO

3)2

11.4 pt.Ca(NO

3)2

2 gal.Ca(NO

3)2

2.4 gal.Ca(NO

3)2

or 4.6 lb. dryCa(NO

3)2

or 6.2 lb. dryCa(NO

3)2

or 7.9 lb. dryCa(NO

3)2

or 11.1 lb. dryCa(NO

3)2

or 13.3 lb. dryCa(NO

3)2

0.7 lb. Fe 330 0.7 lb. Fe 330 0.7 lb. Fe 330 0.7 lb. Fe 330 0.7 lb. Fe 330

---------------------final concentrations (ppm)------------------------

N 70 80 100 120 150

P 50 50 50 50 50

K 120 120 150 150 200

Ca 44(35)z 59(47) 75 (59) 105 (83) 127 (100)

Mg 40 40 40 48 48

S 56 56 56 67 67

Fe 2.7 2.7 2.7 2.7 2.7

Cu 0.28 0.28 0.28 0.28 0.28

Mn 0.7 0.7 0.7 0.7 0.7

Zn 0.39 0.39 0.39 0.39 0.39

B 0.84 0.84 0.84 0.84 0.84



Mo 0.06 0.06 0.06 0.06 0.06

ZNumbers in parentheses are the ppm Ca when dry Ca(NO3)2 is used instead of liquid.

NOTE: Calculations in above table are for amount of fertilizer material in 30-gal stock tanks and then for a 1:100 (1 gal each stock in 100 gals final nutrient solution). Fertilizer amounts placed in each stock tank will need be doubled if proportioner (1:100) pumps are installed in parallel in same incoming water line.

Ca, Mg, and S values will vary upwards depending on the amount of Ca and Mg coming from the water source, and the amount of S coming from the sulfuric acid used for acidification.

HS943

Building a Floating Hydroponic Garden1

M. Sweat, R. Tyson, R. Hochmuth2

1. This document is HS943, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date June 2003. Revised November 2009. Visit the EDIS website at http://edis.ifas.ufl.edu.

2. Michael Sweat, county extension director, Baker County, Richard Tyson, extension agent II, Seminole County, and Bob Hochmuth, extension agent IV, North Florida Research and Education Center – Suwannee Valley. Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie

Ferrer-Chancy, Interim Dean

The Aztecs amazed the Spanish conquistadors with their floating gardens, and now 500 years later you can impress your friends and neighbors with yours. A floating hydroponic garden is easy to build and can provide a tremendous amount of nutritious vegetables for home use, and best of all, hydroponic systems avoid many pest problems commonly associated with the soil. This simple guide will show you how to build your own floating hydroponic garden using material locally available at a cost of about $50.00 (Figure 1).

Figure 1. Lettuce in floating garden system.

Construction Steps

• Build a rectangular frame using 2-by-6-inch or 2-by-8-inch treated lumber. The frame should be 4 feet, 1-inch wide by 8 feet, 1-inch long. This size frame eliminates the need to trim the floating styrofoam, however, the size can be varied to suit personal needs.

• Line the frame with a 6-mil polyethylene plastic sheet to form a trough to contain the nutrient solution. Be sure the site is level and free of any debris, which could puncture the plastic liner.

• Secure one end and side of the liner to the top edge of the frame with 1-by-2 inch furring strips or lattice using wood screws or small nails.

• Place a 4-by-8-foot sheet of 1 1/2 inch thick styrofoam insulation in the lined frame. Make sure the edges have sufficient room to allow the garden to move up and down. If necessary, adjust the frame to make it square with the styrofoam. The styrofoam sheet will create a floating platform in the wooden frame you have constructed.

Building a Floating Hydroponic Garden 2

• Fill the water garden with approximately 20 gallons of water. The water will form the plastic sheeting to the sides of the frame. Secure the other end and side of the liner to the top edge of the frame.

• Continue filling the water garden with water to a total depth of at least five inches. Keep track of the total gallons of water you add.

• Add water-soluble fertilizer, such as 20-20-20 with micronutrients, at a rate of 2 teaspoons of fertilizer for each gallon of water used in the water garden. In addition, add Epsom Salts (magnesium sulfate) at a rate of one teaspoon for each gallon of water. Use a soft broom to mix the water & fertilizer in the garden or premix all fertilizer in a bucket before adding to water garden (Figure 2).

Figure 2. Nutrients needed for floating garden.

• Light rainfall will have little effect on the water garden; only extensive flooding would require fertilizer adjustment based on the amount of water added by rainfall. The solution in the garden needs to be replaced periodically for optimum production. You can grow two crops of salad greens in the same solution before changing the entire solution and starting with a new batch.

• Commercially available "net pots" (Figure 3) or styrofoam coffee cups with slits cut in the bottom may be used to hold the young seedlings.

• Use a hole saw or sharp knife to cut holes in the styrofoam. A 2 1/2-inch hole saw is needed to drill the correct-size holes in 1 1/2-inch thick styrofoam when using the 3" Net Pot or a styrofoam cup with slits cut in the bottom and trimmed at the top. Using 2" Net Pots will require a 1 3/4-inch hole saw for the 1 1/2-inch styrofoam (Figure 4). The hole size should allow the bottom of a cup to be level with the underside of the styrofoam. It is very important that once the cups are placed in the holes, they do not extend down lower than 1/16 inch below the bottom of the styrofoam sheet! This allows the root mass to wick up water without being totally submerged, which might lead to drowning of the root and plant death.

Figure 3. Lettuce transplant in net pot.

• Optimum plant spacing for most plants would be 6 inches from the sides and 12 inches apart to form 32 holes for planting.

• Transplants used in this system should be grown to be fully rooted in a typical soilless media. Transplants can be grown at home in many root ball shapes in a loose media, purchased from garden suppliers, or grown in compressed peat pellets.

• Place young starter transplants directly into the cups. Use toothpicks, if desired, to hold the transplant in an upright position. Do not remove the potting soil from the transplant.


Figure 4. Drilling holes in styrofoam for transplants.

• The most critical aspect is the depth of placement of the net pot or transplant root ball in the solution. Do not place the pot or transplant too deep in the solution. A flat bottom transplant cube or disc media will wick up more water than a pointed root ball. If the media seems too wet, tilt the cube so only a portion of the root ball actually touches the water.

• After placing the young transplant in the net pot or styrofoam cup, do not add any potting mix or other material around the young transplant as this will keep the roots too wet and inhibit oxygen intake (Figure 5).

• Add extra water and fertilizer as needed to keep the styrofoam sheet floating on a minimum of 5-inches of solution.

Figure 5. Hydroponic lettuce root system.

Crops

Several leafy salad crops such as lettuce (romaine, boston, bibb, & leafy lettuces, Figure 6), mustard greens, mizuna, mint, and kale grow well during the cool season. There are fewer crop options for the warm season, however, basil, Swiss chard, cucumber, watercress, and some cut-flowers, like Zinnia and sunflowers have done well. Growing with floating systems does not override the normal challenges of gardening in the warm season in Florida.

Figure 6. Healthy lettuce being grown in a standard 4x8 ft floating garden.

Not all crops do well in the floating gardens; however, small-rooted, short-season crops generally grow well. Crops that prefer wet rooting conditions grow better than those that prefer dry conditions. For example, watercress grows very well, and periwinkle does not grow as well in a floating garden.

Container Choices

This publication guides you in the steps to build a 4x8 ft floating garden using wood and a plastic liner. Many simple containers can also be used to make a floating garden. Examples include: children's pools (kiddie pools), small plastic storage containers, trash cans, and buckets. Many shapes and sizes of containers will work, but they should be able to maintain a 4-6 inch depth of nutrient solution for the best success.


New Research

Ongoing research with plants such as tomato in floating systems indicate that larger plants may require more above-water rooting volume (more air-space) in order to produce successful yields. To produce more root mass above the water, you may want to test a system that uses two stacked styrofoam floats with holes drilled in the bottom one and all but a six-inch edge around the perimeter cut out of the top one. Fill the empty top float with perlite, vermiculite, or other hydroponic media and plant vegetables or flowers into it the same way you would plant a normal garden. Preliminary results show this method to be promising if starter fertilizer is used on the young plants until their roots reach the fertilized hydroponic solution below the floats.

Tomatoes and peppers are also challenging to grow in floating systems due to the high nutrient requirements for calcium. Blossom-end rot is caused by low calcium in the fruit. Supplemental calcium can be supplied in addition to the recipe above. These calcium products are available at most of the same suppliers that sell the net pots.

Additional Resources

For more information on hydroponic production, please visit our website at http://smallfarms.ifas.ufl.edu. A copy of a DVD on the topic of “Building a Hydroponic Floating Garden” may be purchased for $15, plus tax, by contacting the IFAS Bookstore at (352) 392-1764 or online at http://www.ifasbooks.ufl.edu, DVD295. The video is also available to view online on the Virtual Field Day website at http://vfd.ifas.ufl.edu as part of a series of hydroponic video modules.

Hydroponic Suppliers

Aquatic Ecosystems, Inc. - http://aquaticeco.com 1-877-347-4788 - net pots, hobby kits, hydroponic supplies.

Hydrogardens, Inc. - http://www.hydrogarden.com 1-800-634-6362 - net pots, hydroponic supplies.

Verti-Gro, Inc. - http://www.vertigro.com 1-352-347-9888 - vertical hydroponic gardening supplies.

CropKing, Inc. - http://www.cropking.com 1-800-321-5656 - hydroponic supplies, hobby greenhouses.

Worm's Way, Inc. - http://www.wormsway.com 1-800-283-9676 - hydroponic supplies, hobby kits.

Note: This is a partial list of suppliers of hydroponic materials and supplies. Mention of the above suppliers is not intended to be an endorsement of their product or a preference over other suppliers.

Kidsgardening.org

Exploring Classroom Hydroponics


Growing Edge http://www.growingedge.com/basics/tutorial/01_history.html

S.H.A.R.P. Lesson Plans for Hydroponics http://library.thinkquest.org/C0110342/lessonplan

Verti-gro Systems


Hydro-stacker Systems


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