GROWING STRAWBERRIES BY HYDROPONICS

Summary of a talk given by Rocky Caltieri, of Wandin, Victoria to the Hydroponic Society of Victoria in June 1987

Rocky, a commercial strawberry grower, started experimenting with hydroponics in the open in 1978. He set up an N.F.T. (nutrient film technique) system using 90mm PVC pipes as channels. With this system he achieved a much higher plant density compared to normal field growing. Although the plants looked good in the channeling system, each plant on average produced one punnet of fruit compared to up to ten punnets per plant from field grown strawberries. As a result, in 1975 he changed to a system of produce boxes and scoria on waist high benches. Each box contained 4 plants yielding 4-5 punnets per plant. This method indicated that hydroponics was commercially viable. However, the main drawback of this system was the weight of the scoria filled boxes. So in the early 1980’s Rocky began trials with horticultural rockwool. He replaced the scoria with rockwool slabs and the plants continued to yield well. The next problem was the cost of the rockwool slabs, at 4 times the equivalent quantity of scoria, it appeared financially inefficient.

Then there was the problem of disposing of the waste rockwool. In recent years, Rocky has changed to growing in wrapped rockwool cubes (75x75x65 mm high) and replaced the boxes with specially constructed channels again at waist height. Plants are spaced at 125 mm (5″) intervals in single rows. In all of his systems he has recycled his nutrient solution. In summer, the solution is recirculated continuously, but in winter it is down to running for 1 hour per day. The nutrient solution is replaced completely every two months. The electrical conductivity (EC) is maintained between 2 and 3 ms, and the pH adjusted to between 6 and 6.5. When the pH was allowed to rise to 8, Rocky found the fruit to be noticeably drier. Rocky stressed a number of important points about strawberry growing:

1. There are two main times to plant strawberries in southern Victoria: Winter-June-July (fresh runners), and Summer-January (frozen runners). This late planting enables the plants to develop good crowns and therefore results in good cropping potential for the following spring.

2. What varieties to grow in hydroponics? Tioga and Shasta are very large plants and sometimes the fruit quality can be affected. Rocky favors Red Gauntlet, these in his experience produce the best quality fruit.

3. Why not in a greenhouse? The strawberry is a temperate climate plant, and requires cool winters end warm summers for good fruit production. Therefore it is best grown in the open. In greenhouses, it is possible to grow fruit all year round, however the fruit in winter is tasteless, flowery and unevenly ripe. These days strawberries are grown in the northern states and shipped to Victoria to fill the demand of the winter market anyway.

4. Yields in hydroponics: Current strawberry yields per plant are slightly lower than those grown in scoria or soil. However quality is very good and wastage is only about 1% compared with up to 20% for soil grown plants. Also picking is less fatiguing.

5. Flavor of strawberries: There is no consistent difference between hydroponic and soil-grown berries. With those grown in hydroponics, fruit acidity appears to vary with the time of day; those picked in the morning tend to be sweeter.

6. Source of strawberry runners: Always use runners that are certified virus tested. These are available from Toolangi Certified Runner Growers’ Cooperative.

7. Spraying of plants for diseases and insect pests: As for soil grown crops, except not as heavy a dose is necessary. Red Spider mite is not as severe a problem in hydroponics.

 

Courtesy of the Hydroponic Society of America. Used by permission.

 

Summary of a talk given by Rocky Caltieri, of Wandin, Victoria to the Hydroponic Society of Victoria in June 1987

Rocky, a commercial strawberry grower, started experimenting with hydroponics in the open in 1978. He set up an N.F.T. (nutrient film technique) system using 90mm PVC pipes as channels. With this system he achieved a much higher plant density compared to normal field growing. Although the plants looked good in the channeling system, each plant on average produced one punnet of fruit compared to up to ten punnets per plant from field grown strawberries. As a result, in 1975 he changed to a system of produce boxes and scoria on waist high benches. Each box contained 4 plants yielding 4-5 punnets per plant. This method indicated that hydroponics was commercially viable. However, the main drawback of this system was the weight of the scoria filled boxes. So in the early 1980’s Rocky began trials with horticultural rockwool. He replaced the scoria with rockwool slabs and the plants continued to yield well. The next problem was the cost of the rockwool slabs, at 4 times the equivalent quantity of scoria, it appeared financially inefficient.

Then there was the problem of disposing of the waste rockwool. In recent years, Rocky has changed to growing in wrapped rockwool cubes (75x75x65 mm high) and replaced the boxes with specially constructed channels again at waist height. Plants are spaced at 125 mm (5″) intervals in single rows. In all of his systems he has recycled his nutrient solution. In summer, the solution is recirculated continuously, but in winter it is down to running for 1 hour per day. The nutrient solution is replaced completely every two months. The electrical conductivity (EC) is maintained between 2 and 3 ms, and the pH adjusted to between 6 and 6.5. When the pH was allowed to rise to 8, Rocky found the fruit to be noticeably drier. Rocky stressed a number of important points about strawberry growing:

1. There are two main times to plant strawberries in southern Victoria: Winter-June-July (fresh runners), and Summer-January (frozen runners). This late planting enables the plants to develop good crowns and therefore results in good cropping potential for the following spring.

2. What varieties to grow in hydroponics? Tioga and Shasta are very large plants and sometimes the fruit quality can be affected. Rocky favors Red Gauntlet, these in his experience produce the best quality fruit.

3. Why not in a greenhouse? The strawberry is a temperate climate plant, and requires cool winters end warm summers for good fruit production. Therefore it is best grown in the open. In greenhouses, it is possible to grow fruit all year round, however the fruit in winter is tasteless, flowery and unevenly ripe. These days strawberries are grown in the northern states and shipped to Victoria to fill the demand of the winter market anyway.

4. Yields in hydroponics: Current strawberry yields per plant are slightly lower than those grown in scoria or soil. However quality is very good and wastage is only about 1% compared with up to 20% for soil grown plants. Also picking is less fatiguing.

5. Flavor of strawberries: There is no consistent difference between hydroponic and soil-grown berries. With those grown in hydroponics, fruit acidity appears to vary with the time of day; those picked in the morning tend to be sweeter.

6. Source of strawberry runners: Always use runners that are certified virus tested. These are available from Toolangi Certified Runner Growers’ Cooperative.

7. Spraying of plants for diseases and insect pests: As for soil grown crops, except not as heavy a dose is necessary. Red Spider mite is not as severe a problem in hydroponics.

 

Courtesy of the Hydroponic Society of America. Used by permission.

 

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