An Organic Hydroponic Backyard Garden

By Peggy Bradley

This last summer, a basic backyard garden was established at the Institute of Simplified
Hydroponics (ISH) in El Dorado Springs, Missouri. This experimental garden was the first, all-organic garden attempted at ISH.

The garden was grown using coco fiber substrate and an organic hydroponic nutrient. Thanks to a generous donation from American Hydroponics, several commercially available organic hydroponic nutrients were used in the garden.

The small backyard garden was successful in supplying one to two pounds of fresh vegetables every day from June until October last year. It continued to produce through the summer and early fall, until the first frosts killed the outdoor garden. The vegetables produced included tomatoes, bell peppers, lettuce greens, onions, carrots and asparagus.

The vegetables produced in the garden reduced the food budget to about $75 a month, so the total value of vegetables produced in the season was about $375. This was the usual cost of fresh vegetables for the ISH workers’ groceries.

Garden Requirements

The garden area included a small, 100 square foot outdoor patio and two-16 square foot tables. The asparagus was grown in a separate small grower made out of a child’s swimming pool.

Tomatoes

The tomato growers were three patio or window box type plastic growers, which cost about $6 each. The growing boxes were modified with a hole cut near the bottom, about one inch from the bottom surface, and a plastic fitting put in the hole that can be attached to a drain line.
The three tomato growers were filled with coco fiber, filled with substrate about two inches from the top of the grower. They were selected from starts in the store, but could have been started from seeds. There are many varieties that can be grown, but the type of tomato that needs to be grown is indeterminate, or a vine type that will continue to grow and produce tomatoes for a whole season. The determinate types will produce a lot of tomatoes all at once, not the best option for a daily salad.

Indeterminate tomatoes include Big Boy, Beef Master, most cherry types, Early Girl and most heirloom varieties. Determinate tomatoes include Roma and most bush varieties. For this summer, garden two types of indeterminate tomatoes were grown - Big Boy and a Greek heirloom variety.

Bell Pepper

Bell peppers for the salad were grown in larger plastic pots about 12 inches in diameter. These pots were modified for hydroponics with drains placed about an inch from the bottom.
Bell peppers best used in a hydroponic garden are California Wonder, and the colored bells of yellow, purple and chocolate. Each are grown in its own pot and picked as they ripen with color. Four plants should produce at least one pepper a day.

Salad Greens

Every day salad greens are ready for salads and sandwiches. The head forms of lettuce such as iceberg are not as successful in hydroponic culture. More successful types are loose-leaf lettuces such as Buttercrunch and Red Sails. The Red Sails variety is especially beautiful with red tinged leaves and it is much more resistant to bolting in hot weather.
For our salad greens, we grew a variety of greens in a tray grower. They tray grower can be any kind of plastic tray with sides of about four inches tall, but a great choice is a hod mixing tray of about two feet by three feet in size. Two of this type of grower is enough to grow one head of lettuce every day.

Asparagus

Hydroponic asparagus is a bit tricky. The roots are purchased at two years old and grown for a year without harvest. We purchased Martha Washington roots and grew them in coco fiber substrate.

The asparagus pool grower was made from a plastic pool. Although the asparagus grew all summer, it was never large enough for harvest. It should be producing all next season, which will increase the value of the outdoor garden produce about $20 a month.

Onions and Carrots

The salad onions were grown in another hod carrier grower. There any many types of onions that can be grown in the hod grower but the best for salads is the spring onions. This type of onion is very flavorful and grows rapidly in hydroponics. Five to six onions were harvested every day during the summer.

Carrots were also grown in a hod carrier grower, but they remained small all summer. Even though they were flavorful and used in salads and cooking, more work needs to be done to call organic carrots a successful crop.

Setting Up the Garden

The following parts were purchased:

1. Three window box plastic growers (three feet by six feet by four inches). These should not have any holes in the bottom.
2. Three hod carrier growers (two feet by three feet in surface space and four to six inches deep).
3. Four plastic pots (12 inches in diameter).
4. Enough substrate for all the growers (About four cubic feet). The preferred substrate is coco fiber that can be compressed.
5. Seeds for big boy tomato, red sails lettuce, spring onions and asparagus.
The total cost to set up the hydroponic garden was about $83. The operational costs of the hydroponic garden were quite high and showed there are needs for conservation in the backyard garden.

For this season we used city water for the garden. The garden used about 12 gallons of water every day and the cost of this was about $5 per month. The water costs could be more in many cities and cultures and so there is a need for establishing rainwater harvesting for a backyard garden to be economical.

The organic hydroponic nutrients were also costly, and the total value in nutrient used in the garden was $45 over the season. This cost could be reduced if a hydroponic nutrient was made onsite, but a good source of animal or fish manure would be needed. As of now the garden does not have a worm farm, a bio-digester or a source of animal manure so commercial hydroponic nutrient is needed.

The commercial organic hydroponic nutrients did not supply enough calcium for the plants. This was true of every nutrient tested in the garden and was corrected by using calcium nitrate as a supplement for the water supply. This was accomplished by adding a tablespoon of calcium nitrate per 50 gallons of water.

The calcium deficiency was shown in the tendency of the early tomatoes to show signs of blossom end rot, a darkening of the ends of the tomatoes. It is a condition that often happens with tomatoes grown in soil as well.

Conclusion

Overall the organic backyard garden was a tremendous success for reducing food costs for the summer. This garden also provided a steady supply of fresh vegetables, increasing the food value and quality of the daily diet, and reduced cost in going to the store to obtain the vegetables.

If ISH can build a lean-to greenhouse the garden can be grown year round, and will probably produce annually about $840 worth of fresh produce.

Article Courtesy of Maximum Yield Publications Inc. Bradley, Peggy, “An Organic Hydroponic Backyard Garden”, Maximum Yield’s Industry News, April 2009, pgs 38-39.

www.maximumyield.com