Choosing a Growing Method

THERE ARE A LOT OF CHOICES confronting the soon-to-be indoor gardener. Choice is good, but it can get a little overwhelming and the novice grower may soon have difficulty seeing the forest for the trees. When considering what type of growing materials and equipment you will require, it is important that you first determine how you intend to grow. Choose a cultivation practice that suits your skill level and perhaps your busy lifestyle. The following is a basic overview that may help shed some light on the strengths and weaknesses associated with four basic types of growing: organic, hydroponic, soilless, and aeroponic.

1. ORGANIC

A fertile and biologically active soil is the key to most successful organic gardens. Alternatively, some growers are able to achieve respectable results using relatively inert media while supplying nutrients in the form of biological (organic) solutions, an alternative to conventional hydroponics (salt nutrients).

Some feel that organics is about feeding the soil, not the plant. This may be true, because growers must focus on the soil environment rather than strictly focusing on plant uptake requirements. It is the healthy soil life cultivated in the growing medium that the grower develops, which in turn can supply the crop with a more complex and diverse array of macronutrients, micronutrients, sub-micronutrients, enzymes, hormones, vitamins, proteins, bacteria, fungi, and a host of other naturally occurring beneficial elements for the plant. If growing is a two-dimensional activity, the biological life associated with organic cultivation creates a third dimension.

For premium organic crops, the grower may need to be prepared for a larger initial investment in growing materials. For example, a bale of commercial peat mix and a good quality liquid- or dry-nutrient feeding program will typically cost one-quarter to one-half of the equivalent in specialty organic growing media, amendments, and nutrients.

However, in addition to the improved quality associated with organic produce, there is a possible financial advantage. With proper management, the organic growing medium may be reused for multiple crops, often with each use resulting in improved results.

Inorganic nutrients, such as hydroponic-type fertilizers, are manufactured from chemical-based salts. Besides nutrients, they contain elements that crops may prefer not to assimilate. The result is an increasing level of impurities in the root zone that compounded over time may become detrimental to crop growth. Furthermore, they are less conducive to developing healthy biological activity in the root zone. Microbial soil populations increase when chemical fertilizers are not applied.

Some markets command a premium for organically grown produce. In a competitive or saturated marketplace, organic certification can provide the savvy marketer with a viable competitive edge.

Organic crops may encounter fewer diseases or insects. Biologically healthy plants are less susceptible to attacks and tend to produce better when there is a significant insect infestation or incidence of plant disease. In a controlled experiment, plants being grown organically versus inorganically, with all other factors being equal were significantly less susceptible to powdery mildew than their inorganic counterparts. The chemically fed plants produced respectably, but yielded 25 to 30 percent less than the organic plants from the same garden.

When factoring in the increasing cost of chemical fungicides, insecticides, etc. and the cost of their application, the increased initial investment in organics may provide additional savings of other inputs further into the crop cycle. Costly electronic nutrient monitors (EC, pH) are required for management of inorganic nutrient solutions, whereas they are generally of little value for organic nutrient applications.

Specialty organic materials may be difficult to obtain in some locations, in part due to their large bulk when considering shipping and handling requirements relative to the value of the material. But rest assured, you can buy ground-up coconut husks in Alaska; just be prepared to pay for them. Experienced growers with some understanding of the biological processes associated with crop nutrition may be able to improvise with locally obtainable materials. Along the coast you may have an abundance of seaweeds, kelps, fish meals, crab meals, oyster shells, etc., which are all excellent sources of nutrients. In interior regions you may find oilseed meals, fish meals, animal feed products, and naturally occurring mineral nutrients, which may also be used to produce organic crops with good results. Depending on the material, it may be added directly to the soil/soilless mixture to release nutrients or possibly extracted in an organic tea fertilizer extract.

2. HYDROPONIC

Hydroponic plant production systems can range from simple to very complex in construction and management. True hydroponic systems use no growing media; plants are mechanically supported and nutrients are supplied in a hydroponic fertilizer solution. The solution may be recirculated throughout the growing media or drain-to-waste. The nutrient solution may be applied intermittently or constantly.

In a hydroponic nutrient solution, plant nutrients are supplied chemically in specific ratios and quantities in a variety of plant-available forms to optimize nutrient uptake. Nutrients can be precisely formulated for optimal nutritional levels in each stage of the plant’s development. Essentially, growers may tailor a nutrient diet for their specific growing variety, cycle, and conditions. With experience, growers may be able to “push” crops with intensive nutrient management. Complex hydroponic systems are not often recommended for inexperienced growers or those lacking time to monitor and adjust the system. However, novice growers who have purchased complete aeroponic systems supplied with a level of support, specific nutrients, and application directions have had some incredible results. Sometimes the novice grower looks to save money and attempts to construct or replicate a complex hydroponic system. The results can be poor due to the grower’s focus on system design, construction, and operation, rather than on actual crop management. Construction is what a professional manufacturer would call product development. Be prepared for the possibility of a steep learning curve when fabricating a new system if you are relatively new to growing or growing system construction. For example, using the wrong kind of adhesive may be the kiss of death. If you are not aware of what you are doing, the crop may be finished before you even plant it.

Besides the exacting level of nutrient management required of the grower with hydroponics systems, turnaround time between crops can be very quick. Crops tend to produce faster in a well-tuned hydroponic system, and can be harvested sooner. The fact that more plants can be grown in less space also allows for less growing time between planting and harvest. More plants in less space means that plants flower, fruit, or bud sooner because less time will be required in the vegetative phase to achieve optimal plant densities. Basically, with higher planting densities you have more branches sooner. More plants with fewer branches take less time to reach optimal flowering size.

Downtime, which can be costly for the commercial grower, is minimized. The system can be cleaned and replanted relatively quickly. In a true hydroponic system only a handful of growing medium is used per planting, so there is physically much less to handle. Systems are cleaned of debris and scrubbed or rinsed with a 10 percent bleach solution. Nutrient delivery systems are also sterilized by pumping a bleach or hydrogen peroxide solution through them. With experience, the system can be replanted within a day. With media-based systems, if the medium cannot be reused, it must be removed from the growing site and replaced. This can be very laborious and messy. For the larger grower, this may require handling truckloads of material. For the apartment dweller, lugging bales of soil up and down the stairs or elevator simply isn’t appealing. Sterilization is equally or more demanding relative to the amount of growing medium.

3. SOILLESS

At present, this is the most common type of indoor cultivation practiced. Plants are grown in an organic-based medium, which is relatively inert — containing little or no available plant nutrients. Nutrition is supplied to the plant via chemical fertilizers or a combination of chemical nutrients and organic supplements. The cost is relatively inexpensive and materials are widely available due to widespread commercial applications of this growing method. Soilless cultivation combines some of the benefits of media-based growing while affording the grower relatively simple and inexpensive nutrient regimens.

Commercial soilless planting mixes are available in a variety of packages and brands, but most commonly used for indoor or greenhouse growing applications are the 3.8-cu.-ft. bales, which expand to about 5 cu. ft. when loosened and potted up. The major ingredient in these is sphagnum peat moss that has been treated for pH and allows for easy wetting. The wetting agent used in most commercially available mixes is not acceptable by most organic-certification boards. The high porosity mixes containing additional perlite and/or vermiculite are preferred by indoor growers. They hold less moisture and provide more air space for roots. When applying chemical fertilizers to media-based systems a faster draining texture is preferred. This allows more frequent irrigations with higher volumes of solution. A 20-percent runoff (applying at least 20 percent more than is required to moisten the media) is desirable because it helps to “flush” or leach away excess nutrients and salt accumulations from the root zone. A buildup of salts (resulting impurities) and unused nutrients from chemical fertilizers can create a chemical imbalance for nutrient uptake and may reach levels that become toxic to the plant. More recently, coconut coir (coconut fiber) has gained much popularity as a substitute to commercial peat mixes. These products tend to be competitively priced and offer some advantages over commercial peat mixes.

Some growers have been able to reuse soilless mixes that have been fertilized with chemical nutrients. This is more likely to be successful if there have been large, deep, raised beds. The greater volume of media provides a higher level of buffering against the buildup of impurities in the root zone before they reach levels toxic to plants. A fast-draining mixture in raised beds may be leached heavily with hot water for 24 hours and then allowed to dry out. An initial fertilizer application is then applied to adjust pH and provide an initial dose of nutrients, followed by planting.

Large harvests have been achieved with soilless cultivation, but the average grower should expect consistent but average yields. Soilless cultivation is also a more forgiving growing method and has a lower initial cost. However the frequent replacement of medium over multiple crops can become more expensive than more sustainable cultivation methods such as organics.

4. AEROPONIC

Aeroponics is the sports car of cultivation methods. You can achieve extremely fast growth rates with an increased level of control or you can wrap yourself around a telephone pole, so to speak. There are several types of aeroponic systems available to the grower. As far as most institutional researchers are concerned, aeroponic systems provide mechanical support to plants and apply a highly oxygenated nutrient mist to bare-rooted plants. Another factor in defining an aeroponic system is the volume of air available in the root zone for plants. Shallow trays and tunnels are not particularly advantageous for high-volume misting or ambient-air availability.

Since there is no growing medium to buffer the roots, this type of system can be very temperamental. If not carefully controlled, the roots quickly overheat and root disease sets in. Nutrient concentrations and pH levels must be monitored carefully. A clogged mister can lead to the demise of plants or entire crops.

The level of control that an experienced grower may obtain from aeroponic growing methods can be phenomenal. Plants may grow to Jurassic proportions in a very short amount of time. Nutrient availability to the plant can be very high.

The Ein Gedi system was developed in Israel and integrates some deep-water attributes found in some hydroponic systems to provide a more forgiving method of aeroponic growing. There is still plenty of air space around the roots in deep growing vessels. However, the lower portion of the growing vessel contains a significant depth of nutrient solution. The roots in the upper portion receive mist and ambient air and extend a good distance into the nutrient solution below. In the event of power failure or misting system failure, water and nutrients are still available to the plant because the lower portion of the roots remains immersed in solution. This depth offers further advantage because it helps to buffer temperatures in the root zone, acting as insulation for the roots. Nutrient concentrations and pH levels may fluctuate less because of the increased buffering action of the relatively large volume of solution available at the roots.