Hobby Organic Growing Systems

The reasons for growing plants “organically” vary from one person to another. Some people would like to reform the world of modern agriculture, starting in their own corner. Others are interested in producing their own food in an environment free of substances either known to be or perceived to be harmful. The purpose of this article is not to establish nor justify any of the possible reasons for growing organically. Instead, we’ll be focusing on organic growing procedures and techniques that can be applied on a small scale.

Many growers considering moving toward organic systems have questions about organic certification. The requirement to undergo the certification process applies only to commercial “organic” growers. Hobby growers do not need to go through the certification process, but they may want to refer to the certification requirements as a guideline for what is available for use in commercial growing, and select what they may want to incorporate into their small organic systems. The website containing this information is www.usda.gov/nop.

There are several available choices when selecting a hobby-level growing organic system. The development of the system described in this article and shown in the accompanying photos involved a series of tests and evaluations over time. Initially, three different potential systems were evaluated and compared to a standard hydroponic bucket production system. From that trial evaluation, a trough “organic” production system was selected and has been improved and refined through four successive year-long crop rotations to create the system which is available today. It was developed to be a certifiable system because it is used by commercial “organic” growers throughout the United States.

This system is just one of many potential systems that a new organic grower can use. The combination of components in this system is functional both as a small or large growing system and can also meet certification standards as an “organic” production system.

It should be noted that an organic system differs from a hydroponic system and requires different components because the nutrients which are used in an organic system require growing media (not necessarily soil) to make the nutrients available to the plant roots. So, an organic growing system uses growing media such as perlite, peat and compost instead of water alone.

The Plant Production System

The growing media container used in this system and shown in many of the photos is a flexible, multi-plant container. It is a trough or channel that comes in a lay-flat roll. Channel can be cut to various lengths, and ends are made with the roll material itself, allowing the trough to be made up in any length. Plastic pins fit along the outside of the trough and are positioned opposite each other along the track, and bands are strung between the pins, across the channel, to keep the sides of the trough upright.

Slightly elevating one end of the trough creates a gentle slope to allow for drainage. The surface upon which the trough sits should have a slope ranging between one half to two per cent. This is critical in a large commercial installation. If it is not possible to accomplish a slope in a small hobby setup, a shorter trough of 20 feet or less in length will work adequately if it has to remain level from end to end. Drainage will run out of a trough up to 20 feet in length even if it is not sloped.

A two-inch diameter plastic field drain line is run down the middle of the trough. This provides drainage to the media. When there is a slope to the trough, the drain line will pass through a hole cut in the low end of the trough. In a shorter trough that is not sloped, the field drain tile can pass through both ends of the trough to provide drainage.

Selecting Seed for Organic Growing

Seed selection is important from several perspectives. Many readily available seeds have been treated with fungicides to help prevent the infection of the young seedling with one or more of several common soil-borne damping-off organisms. These fungicides are not permitted in a certified organic system, and in fact are not permitted in organic growing. The media used contains no soil and has been prepared in such a way that the presence of harmful organisms is unlikely. Organic seeds are available for a wide range of plants, and their use is preferred when they are available.

Most commercial organic growers use hybrid cultivars. The selective breeding used to create these cultivars has created plants which are disease resistant. Resistance to diseases is very important in the production of longer crops in protected environments, especially since pesticides are not used to combat their development in organic culture. The seed from the fruit of hybrid plants should not be used for the next crop of plants to be grown. The plants produced by this seed will not have the uniformity and the characteristics of their hybrid parents.

Some growers, including hobby growers, want to grow heirloom cultivars. Heirloom plants have little if any disease resistance. This makes them more difficult to grow, especially in an extended-length production system like in a greenhouse. There are some products that can be used to combat plant diseases in “organically” grown plants, including heirloom plants. The effectiveness of these is sometimes not adequate for the successful production of a long term crop when there is not maximum disease resistance in the crop plants themselves.

So called “Genetically Modified” (GMO) plants are not accepted as “organic” no mater how they are grown. “Genetically Modified” plants are generally only available for the large commercial agricultural crops at this time. That could change with time. The labeling on the seed should designate the presence of “Genetic Modification”. One of the concerns about “Genetically Modified plants is that their modified properties can be fairly readily transmitted via pollen, and can spread to other plants from a wind-pollinated crop like corn (maize).

Seeding and Seedling Production

Seeding for an “organic” crop must be done in appropriate media containing certain ingredients. The system we’re discussing in this article uses “organically” certified media, which is custom-produced by one of the large media mix companies. This media is available over a wide geographical area, and its consistency enables uniform performance in the hands of different growers.

To begin seeding, seeds are sprinkled out of the package onto a folded file card. A small screwdriver or pencil can be used to individually push the seeds off the card onto the media. Care must be taken that only one seed is used per cell. The cost of the seed is often several times the cost of the media, so it is more advantageous to risk having a few cells without plants than to have many cells with two plants, resulting in one of the plants having to be pulled out and discarded. A little media can be sprinkled on top of the seed after the seeding process is complete. This helps keep the seed moist during the germination process.

Trays of planted hybrid tomato seeds are placed onto heating mats so that optimum temperatures can be maintained in the media. Many of the new tomato hybrids germinate faster and more uniformly if the germination temperature at the seed is 79° to 81° F.
This temperature is on the threshold of being too hot, so close attention and monitoring is needed. One or more thermometers should be used to monitor the media temperature. Because the seeds are in the media, that is where the temperature is important.

The cell trays are placed into a flat that will catch any water that goes through. The use of the flat ensures that the heated propagation mat below the tray will stay dry. Runoff can be discarded by removing the cell tray and emptying the flat. Warmed water is used when the media is irrigated so that the seeds are not cooled during the watering process.

Hybrid tomato seeds will germinate in three to five days at optimum temperatures. Lettuce will germinate in less than a day. Each kind of seed has a projected germination time at optimum temperatures. The optimum germination temperature will change from one kind of seed to another. If temperatures are lower than optimum, germination times will be longer and germination will be spread over a longer period of time. Plants will not be uniform in size because of the difference in germination time, and the overall germination rate will probably be lower than if the optimal germination temperature had been maintained. If the temperature gets too high even for a short time, the plants can become distorted because of erroneous genetic reading, or the plants could be killed entirely.

After the seed germinates, not much appears to happen for a few days. Photosynthesis and cell division, however, have started. The product of those processes is seen after a few days when the first true leaves become visible on the young plants.

As the top of the plant grows and produces more true leaves, the roots grow and knit the media together. There is a window of time during which transplanting into the final media can be done. The 20-day-old tomato plants in the accompanying photo are about the youngest they should be at transplant. In actuality, these plants were transplanted when they were 34 days old, which is at the top end of the transplant time range. If they had been left in the cell trays much longer, their growth would have been slowed.

Media Installation

Shortly before the seedlings are to be transplanted, the media should be installed in the troughs. The media is loose and moist in its shipping bags. This keeps the microorganisms in it more active and ready to do their work in making nutrients available to the plants when they become established. Insoluble and slowly soluble fertilizer ingredients are then measured out and spread on top of the media in the troughs. It is then mixed into the media by hand before the plants are transplanted into it. This all should be done the same day or no more than a day before the plants are transplanted so that the media does not dry out before the plants are transplanted. If there is a delay, the media should be watered as if there were plants in it.

Transplanting

Plants are carefully removed from the seedling starter cell trays so that most of the media and the plant roots remain intact. They are placed in holes in the media that have been dug at the desired spacing (read on for specifics on spacing). The media is placed around the young plant so that there are no big air spaces around the roots to allow them to dry. The media should not, however, be compacted tightly around the plants. If the media is packed too tightly, air flow will be restricted and the plant may not receive sufficient oxygen.

Optimal spacing differs according to plants being grown. Spacing for tomato plants should allow four square feet per plant when aisle ways are included in the space calculations. The amount and availability of light is what determines the spacing of the plants. For tomatoes, this amounts to a double row of plants 16 inches apart in the run of the trough. The troughs are spaced about four and a half feet on center. Seedless cucumber plants should have six to eight square feet per plant. Bell pepper plants and eggplants should be spaced about the same as tomato plants, four square feet per plant. A double top will be maintained on both kinds of plants. Lettuce and many herbs can be planted in the media on eight-inch centers.

Feeding and Fertilizing

The plants in the system’s channels are watered through a drip tape run along the length of the trough. Two lines are run to assure more even watering. The frequency of watering will depend on the age and size of the plants in the trough as well as the relative humidity of the air in the growing area. The system could be watered by hand with a sprinkling can. This would closely tie the grower to the production system. Growers who can stay close to their crops are able to operate small systems by irrigating with a watering can. For the grower who travels or has other commitments, an irrigation system is needed to provide a consistent watering schedule.

Lime and an organic granular fertilizer is sprinkled onto the surface of the media in the trough every two to four weeks. It can also be blended into the top two inches of the media. These additives should be positioned where they will be washed into the media by the water from the drip tape. They could also be watered in using a watering can. A ”nutritional tea” made from compost and/or worm castings is also supplied to the plants between once a week and once a month. The tea is a rich source of microorganisms which are necessary to the process in the media that results in the release of fertilizers which are readily absorbed by the plants.

Modifying the Growing Environment

A greenhouse should be considered for a more flexible, long term organic production system. Although some people might have some success with using this system outdoors during the natural growing season, the enclosure of the production system in a greenhouse will greatly expand the usability of the system over a longer time period. An outline of what a greenhouse can provide, and considerations when using a greenhouse, will be discussed in the following few paragraphs.

Having your own greenhouse would allow you to grow things throughout the year. Heat will be required to not only keep the plants alive but to keep them growing and producing. The cost of both the heating equipment and its operation need to be anticipated as you enter your project. In many climates, heating costs will be at least one of the major operating costs, if not the biggest.

Air movement and ventilation are necessary in the greenhouse. The gas composition and water content of the air are very important to the plants. Air exchange and management systems in the greenhouse contribute to achieving optimal ongoing plant growth. The inexperienced greenhouse grower will tend to overly-limit air exchange in the greenhouse, thus starving the plants and possibly the heating system for the fresh air needed for best performance.

When the weather is cold in the winter, light also tends to be limited. Vegetative plants such as lettuce, various greens and herbs can be grown when light levels are lower. Although they grow more slowly, vegetative plants can grow when there are a few hours of limited-intensity light per day. Fruiting plants like tomatoes and cucumbers, on the other hand, need more light in order to grow and produce fruit. In many geographic areas, fruiting plants must be grown during the times of the year with more light, or artificial light must be used to supplement their growth.

When supplementing or replacing natural light for plant production, high light intensities are needed. Our eyes are not good estimators of light intensity, since they adjust well and rapidly to different light intensities. Regular incandescent or florescent bulbs do not give off nearly enough light to supplement lighting in a plant production environment. High intensity discharge (HID) lights like Metal Halide or High Pressure Sodium lights are needed. Each bulb of an HID light takes four to ten times as much electricity as an 100 watt incandescent light bulb. Adequate electrical power needs to be run to the greenhouse during the construction process if artificial lighting is to be installed.

Insect screening, which has been discussed at length in a previous article, is a very important component of the overall organic production system. Because organic growing prohibits the use of pesticides for pest control, it is very important to exclude the insects from the greenhouse in the first place. The extra effort made to exclude them makes other aspects of operating the system much easier and generally more successful.

Although the main focus of our discussion has been on an “organic” production system itself, the housing for the system is a part of the whole implementation plan. The environmental control is what will greatly allow you to do what you want to do in and with your production system.

Ready to Grow Organically?

Organic growing, with its trickier growing process and its lack of chemical products, may not be for everyone. But for the grower who wants to grow his produce with the fewest possible external products and chemicals, organic growing can be a rewarding and healthy hobby.

James W. Brown has been a horticulturalist in the hydroponic industry for 25 years. He has worked with hobby and commercial growers, helping make them successful in their endeavors. He has a bachelors degree in horticulture from Macdonald College of McGill University and a masters degree with a major in Vegatable Crops from Cornell University. He has written contruction manuals, assisted in developing interactive training CD-roms, conducts grower training workshops and works with growers on a daily basis.