A View From The Fence
Soil Versus Hydroponics
By: Paul Josephs
This matchup would have been great for a Cannabis grower’s version of MTV’s Celebrity Death Match. In all seriousness, there has been much discussion and debate regarding the two choices of how to grow indoors. Let’s compare common concerns like cost, growth speed, yield, quality and effort needed, as well as potential problems to help you decide what works best for you given your unique circumstances and desires.
This is really a comparison of the two styles of indoor growing as compared to growing outdoors in full sunlight and in a rich, sandy loam soil. The latter method is the benchmark to which all other growing techniques are compared. No one who has witnessed a flowering Cannabis plant growing well outdoors can argue that the yields and quality produced are not of the highest order, all other conditions being equal. Sadly, this is not an option for many of us, so we are left to debate how we can grow the absolute best Cannabis in an indoor environment.
Soil and Hydroponic: What’s The Difference?
Let’s start with some definitions. Soils are mineral and organically-derived components mixed together. Naturally occurring soils vary greatly in composition. For the purposes of this article we will be limiting ourselves to premixed soil mixes available at stores offering gardening supplies, and custom soil mixes, which are comprised of a variety of ingredients, including some nutrient-bearing organic components. Plants should be able to obtain some, if not all, of their nutritional needs from soil. Growers can add fertilizer to provide nutrients when they are lacking.
Hydroponics is the growing of plants in which aerated water or mist alone supplies all of the nutrients. Plants can be grown this way with the roots either anchored in an inert, usually inorganic, medium, or completely exposed to water or mist. There are many variations on this basic theme, but the common aspect is the inert medium which requires that growers provide for all the nutritional needs of the plants with nutrient solutions.
Organic Or Not?
This is a complex a topic which will be examined in future articles. Growers who use soil have a choice of nutrients from completely synthetic to completely organic. Hydroponic growers more often use synthetic nutrients, but hydroponic growing can also be organic.
Both soil and hydroponic systems have a wide range of associated costs which are tied to many variables. The cost of a soil system is largely about the soil itself and will differ if the soil is purchased pre-mixed versus if the various components are bought separately and mixed by the grower. Some growers using organic soil mixes reuse the soil to keep costs down.
There is a wide spectrum of hydroponic systems available from automated high tech systems to basic passive ones, and the costs reflect that range. If you have a do-it-yourself approach and a creative eye in the hardware store, it is possible to set up a variety of hydroponic systems quite inexpensively. The initial cost will usually be higher than pots and soil, but once purchased and if using a medium which can be reused, the continuing cost will be only the nutrients and any extra electricity needed for the system.
Aside from the initial product investment, the two methods have similar upkeep costs over time.
All other variables being equal, plants grown in well-maintained hydroponic systems usually will outperform plants in soil. This is because the roots are exposed to an ideal combination of moisture, air and nutrients. Everything is readily available to the plant, so it can devote more energy into growth and flowering.
Plants will grow faster and yields are usually greater in the hands of a skilled grower who knows what nutrient levels are ideal for the plant. This is true for both soil and hydroponic growing. This skill and expertise is easier to achieve for an observant grower with a hydroponic system. The cause and effect of nutritional changes appear sooner with hydroponics, making it easier to correct adverse reactions. Conversely, soils tend to buffer or mitigate changes in nutrients and water chemistry, which will often obscure the actual cause of the observed changes.
Since plants generally grow faster in a hydroponic system than in soil, the hydroponic grow room will produce more yield over time. There is generally also more yield realized per plant grown hydroponically. In comparison, skilled soil growers can expect to see less yield per plant than their water-based brethren, but can take steps to increase their growth rates and yields by employing large volume pots or growbags. These large containers take up room, however, and that can factor into the total yield per square foot of growing area.
Here we delve into arguably the most subjective and contentious aspect of the hydro versus soil debate. Many soil growers, especially organic growers, swear that there is a definite difference in taste between soil grown Cannabis and its hydroponically-grown counterpart. Hydroponic growers claim this is baseless. As noted earlier, this is subjective. Both techniques do benefit from reducing or eliminating fertilizer in the last few weeks of flowering to ‘flush’ excess nutrients from the plants, as it is beneficial to the curing process and taste if the plant has metabolized the nutrients.
Growing Cannabis takes effort, regardless of growing style. Hopefully it is seen as a labor of love. For soil growing, there is the procuring of mixes, potting and repotting the plants, and religiously checking the plants for water. The actual amount of effort needed for hydrating your plants varies in frequency depending on the size of containers as well as the temperature and humidity of the grow room. When the crop is finished, the soil mix must be disposed of or reused, and the containers cleaned and possibly sterilized. Soil mixes can be messy to work with.
For hydroponics, there are nutrient and pH levels to be monitored, equipment and, if used, media to clean after a crop, and checking for leaks and malfunctioning components like pumps. Due to the multiple ways hydroponics can be utilized, there is a wide range of effort associated with the different techniques. Some automated setups can operate for many days without any attention on the part of the grower, and some of the simpler methods may require daily or even more frequent attention as far as watering is concerned.
Both soil and hydroponic methods require some common tasks such as raising lights and checking plants for pests, pathogens and nutrient-related problems.
Let’s look at a few disaster scenarios and see how the two techniques fare. Power outages — depending on the length, these could be disastrous for the more highly automated hydroponic setups, especially ebb-and-flow, bubbler, and aeroponic systems that depend on water and/or air pumps to operate. If it is a long enough outage and the grower is away, the plants could dry out and possibly even die. Soil grown plants usually depend on the grower for watering, but not always — there are automated drip systems and even watering systems for plants grown in soil, and a power outage could be equally disastrous. No matter which method you’re using, the plants will still suffer the effects of light loss, which include slowed growth and stress-related flowering problems like sex reversal.
Equipment failures — systems that rely upon pumps, timers, float valves, switches and other components that could fail are vulnerable, and Murphy’s Law seems to have a particular affinity for mechanical systems. Leaks happen as well, as is illustrated by the grower who was away on vacation when mice gnawed through the water tubing and drained the whole system down. Since his lights stayed on, the entire crop dried to a crisp. Soil techniques, except for the automated cases noted earlier, are exempt from this concern.
Water/soil chemistry problems — pH swings and nutrient imbalances can happen quickly in hydroponic setups, sometimes resulting in a ‘system crash’ where one imbalance causes a cascade effect which causes the nutrient mix to become deadly for the plants. Soil mixes are not immune to this either, but because of the buffering effect of the soil, it is a much slower and therefore more easily remedied process. Some nutrients can substantially change the pH of soil which can in turn affect the ability of the plant to absorb nutrients. Both soil and hydroponic methods are susceptible to over-fertilizing which, in extreme cases, can be fatal.
So — soil or water? Ultimately, it boils down to personal preference. Both methods have their staunch advocates, precisely because they both have many strong points. As the peace-loving members of the tribe, let’s agree to each his own and change the “death match” to a love fest. And pass the Doritos.