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In the simplest terms, hydroponics is a method of growing plants, without any soil. All of the nutrients and resources needed for growth are provided via an aquatic solution that is flushed through the root zone for plant uptake. These alternative growing systems are quickly increasing in popularity due to their many benefits, and expand the possibilities for urban and indoor gardening exponentially. Plants grown in hydroponics gardening systems use fewer resources and they often yield better than plants grown using traditional gardening methods.
Hydroponics gardening is an intricate system that requires a basic understanding of how the overall system works, what environmental conditions need to be manipulated, how to properly feed plants through a carefully-monitored nutrient solution, and how to keep the system running flawlessly.
This guide is a comprehensive resource intended to provide helpful information on all aspects of hydroponics gardening.
Basics of Hydroponics
While it seems contradictory to grow plants without soil, hydroponics gardening is actually an intricate system that works very efficiently. Physiologically, plants require water, oxygen, carbon dioxide, sunlight, and essential plant nutrients for vigorous growth; the soil solely acts as an anchor to support plants and keep water, oxygen, and nutrients within the root zone. If the essential nutrients are provided in a water-based nutrient solution directly to the root zone and plants are provided ample structural support as they grow, there is no need for soil.
Hydroponic systems have been around for thousands of years, dating back to the Hanging Gardens of Babylon and the Floating Gardens of China. In the 1920’s and 1930’s, the term “hydroponics” was coined by William Frederick Gericks, a plant nutritionist working at the University of California Berkely in an attempt to reduce the need for constant replacement of greenhouse soils or addition of large fertilizer quantities to maintain soil quality.
As the interest in sustainable agricultural technologies has grown, modern scientific advantages couple with an increased knowledge in plant production practices has resulted in hydroponics gardening taking off in popularity in the last 60 or 70 years.
Hydroponics gardening can be accomplished on a small scale by a home gardener, all the way up to large, commercial operations that sell their harvestable goods for profit. Growing plants hydroponically works well for cannabis, flowers, herbs, and numerous fruits and vegetables such as strawberries, tomatoes, brassicas, lettuces, peas, beans, peppers, and tomatoes.
Advantages of Hydroponics Gardening
It’s been proven that gardening hydroponically has distinct advantages over the traditional gardening methods employed by many.
Studies show that when grown under the same conditions, plants in hydroponic gardening systems grow on average 30-50% faster than those sown in soil and have significantly higher yields. This enhanced growth is thought to be a result of the increased oxygen amount in hydroponic nutrient solutions. The extra oxygen stimulates root growth and encourages both easier and faster nutrient absorption; the energy saved is utilized instead for accelerated plant growth and increased yields.
One of the biggest benefits to growing plants via hydroponics is the year-round growing season. Indoor gardening can be accomplished at any time as long as ample light is provided for the plants to complete photosynthesis. In urban environments, the ability to grow plants indoors without soil is providing communities with fresh, local produce year round.
There are also environmental benefits over in-ground gardening. Even though plants are grown in aquatic environments, hydroponic systems actually use less water than traditional gardening. The aquatic solutions are reused in certain systems, keeping water usage lower. Weeds are not a concern in hydroponics, and insect pests are reduced as well — if growing indoors — this cuts down on the number of pesticides and herbicides applied to plants, reducing environmental impacts.
How Hydroponics Gardening Works
Before delving into the intricacies of hydroponics gardening a grower should familiarize themselves with the basic components needed for a hydroponics system, the different systems that can be utilized to feed nutrient solutions to their plants, the environmental conditions they will need to manipulate, and the plant essential nutrients needed for optimal plant growth.
Principal Components of Hydroponics
Being a fully contained system, hydroponics gardening requires more equipment than traditional gardening methods. Especially since many systems are enclosed indoors. Before embarking on a journey to learn the intricacies of hydroponics, a broad base knowledge needs to be understood of the overall nature of hydroponics gardening.
All hydroponics systems consist of a handful of fundamental, highly vital components. A grow system needs sunlight or supplemental light, growing media in which to anchor plants, growing trays/pots to hold the media and plants, a reservoir or reservoirs, nutrient solution to feed plants, an air pump to oxygenate the nutrient solution, and pumps or wicks to move the nutrient solution from the reservoir to root zone of the plants being grown.
Different Types of Hydroponics Systems
While all ll hydroponics systems exhibit similarities in their very basic nature there are differences between them as well. They all supply the three vital components needed by roots for plant growth: oxygen, water, and essential nutrients. The differences lie in how those components are supplied to the roots.
Hydroponic systems are classified based on two different characteristics: how the root systems of the plants receive nutrients via nutrient solutions and if the nutrient solutions are reused into the system.
The first type is passive systems; these systems require no pumps or moving parts making them easier and cheaper to maintain. For this reason, they are often recommended to beginners. These systems use a growing medium –rocks such as hydrocorn or expanded shale, sand, vermiculite, or perlite – through which the nutrient solution is passed. The roots come in contact with the solution, plants then absorb the water and nutrients.
Active systems, on the other hand, are more challenging to set up and maintain; they rely on pumps or other mechanisms to circulate solutions and deliver them to the roots. In active systems, the nutrient solution is typically cycled over and over through the plants’ root zone. The big drawback to active systems is their reliance on electricity; in the event of a power outage, the system quits working.
Passive and active hydroponics systems are then classified as recovery or non-recovery systems. Recovery systems collect the runoff, or leachate after the nutrient solution is supplied to the roots and reused for subsequent feedings. With a non-recovery system the nutrient solution is distributed to the growing media and taken up by the root systems with little to no runoff to collect, so there is no chance to reuse it.
While some variations occur, hydroponics systems fall under one of the following 6 types:
- Wick System – Nutrients are stored in a reservoir, and move into the root zone via capillary action using some sort of wick. This passive non-recovery system is easy to set up and maintain due to a lack of moving parts or pumps making it a great system for beginning gardeners, but it is not the most efficient.
A wick system often keeps the growing substrate wet; too much moisture in the root zone inhibits oxygen from filling the pore spaces, making it harder for roots to draw in what they need and plants have to work harder. It also doesn’t provide a steady stream of nutrient solution to plants so it works best with smaller non-fruiting plants such as herbs or lettuce.
- Drip System – One of the most frequently used systems in hydroponics — especially among commercial growers — a drip system incorporates a submerged pump that delivers the nutrient solution to the base of plants via a line emitter or drip line. Classified as an active system, a drip system can be set up as either a recovery or non-recovery system depending on if the grower chooses to implement the use of drip trays to collect leachate.
Drip systems are very flexible, allowing growers to carefully control the water and nutrient supply delivered to plants, and can easily be scaled up to accommodate a larger grow. They work well when growing a wide range of plants, using many different growing mediums.
Dialing in the drip lines or emitters and the irrigation timing can be tedious and time- consuming during the initial system setup; the grower needs to determine the flow rate needed for plants and how often to schedule irrigation to prevent stress from over- watering or not watering often enough.
- Deep Water Culture System – Commonly known as DWC, deep water culture systems are simple to set up and maintain. In these inexpensive systems plants are held up by a platform of sorts that suspends them above the surface of the nutrient solution; their root systems grow downwards and stretch into the reservoir beneath them to access nutrients. Air pumps and air stones then provide oxygen to the plants, much like in an aquarium.
The drawback to deep water culture systems is they do not work well for large plants or plants with a longer growing season; few plants other than lettuce do well in these hydroponics systems.
- Nutrient Film Technique (NFT) System – In this type of system plants are suspended in long channels — sans growing media — with nutrient solution constantly running along the bottom of the channel. The channels are angled slightly downward, allowing gravity to move the nutrient solution through the channel.
NFT systems are very popular in commercial operations, but require pumps and timers
to control the delivery of nutrient solution to plants. Larger, heavy plants are not suited for nutrient film technique systems and a reliance on pumps and timers makes the system susceptible to problems if a power failure occurs.
- Ebb and Flow System – In an ebb and flow system (also known as fill and drain), plants are grown in trays filled with the appropriate growing medium. On regular intervals, the trays are flooded with nutrient solution and then drained back into a reservoir until the next cycle.
The ebb and flow systems are very versatile systems but are not as popular as the other
designs. More so than the other hydroponics system designs, it has a higher risk for flooding if there is pump failure, salt buildup on roots occurs because of the draining of water, and the constant ebb/flow creates a situation of unstable pH levels in the nutrient solutions.
- Aeroponic System – An aeroponic hydroponics system is the most technical setup of the active systems. Plants are suspended in the air without any growing substrate and roots are periodically misted with a nutrient solution either on a timed cycle or continuously for non-recovery of the solution.
They are more expensive to set up than the others systems and aeroponic systems
obviously require more technical equipment such as pumps and misters. They are not recommended for first-time growers.
Environmental Conditions to Manipulate
It is true that most plants will grow if they are given adequate nutrition and water, but for optimal growth, it is important that they also have the perfect environmental conditions. The combination of a great environment and sufficient nutritional resources is what will encourage maximum growth and the highest resulting yields.
Many hydroponics systems are housed within some sort of enclosure, which creates a microenvironment that requires careful management. While the following conditions are rough guidelines it’s important to keep each component in mind when establishing your system, making tweaks to settings until you find the best growing environment for the plants you are growing and their needs.
Light — When it comes to lighting in the growing space, it’s critical plants have all of the light they need for optimal growth. Besides proper nutrient availability, light is going to be one of the key factors in how well the plants grow as sunlight drives photosynthesis, the metabolic process that provides glucose to grow and power plant respiration. The goal in hydroponics growing is to
mimic naturally occurring, outdoor lighting conditions; often with the help of supplemental lighting fixtures. To mimic outdoor conditions means providing plants with 12-16 hours a day of bright light.
Temperature — Behind lighting, the temperature is another critical condition in the grow tent that needs to be monitored. Most plants prefer temperatures within the range of 70 – 80°, or maybe even stretching to 85°F. Many plants prefer the upper range of this spectrum and will grow well if the conditions are slightly warmer. The most important factor in temperature is that it is consistent. Make sure the daytime temperatures (i.e. when the lights are on) is maintained within a fairly consistent range, and that the off-lighting temperatures drop no more than 10- 15°F. In this case, consistency is key.
Relative Humidity — Relative humidity (RH) should be set depending on the ambient temperature of the growing space to keep the vapor pressure deficit (VPD) at optimal levels; the prime relative humidity levels fall between 55-65%. Higher than 65% increases the risk of fungal diseases. Low humidity causes water vapor loss through leaf stomata and stresses the plants. To prevent further water loss a plant will close its stomata, but in turn, this halts photosynthesis as well, leading to a slowing in growth and resulting yield reduction.
Moisture can be added to the air by placing wetted sponges close to growing trays, adding trays/bowls of water close to the plants, or adding larger plants to the growing system that will transpire more.
Vapor Pressure Deficit — Also known as VPD, vapor pressure deficit is an advanced metric used in grow rooms, combining air temperature and relative humidity to express how these two inter-related components affect plants and their nutrient uptake. Vapor Pressure Deficit is the difference between the vapor pressure inside the leaf and the vapor pressure of the air. Low relative humidity (RH) equates to a high VPD: weed plants lose more moisture to respiration, increase their water uptake, and increase their nutrient uptake, often to toxic levels; leaf stomata, also close dropping CO2 levels and photosynthesis slows. High RH equates to low VPD: weed plants reduce water usage, nutrient uptake falls, and growth slows yet again.
To maintain optimal growth, growers need to monitor and manage air temperature and RH to find the VPD sweet spot that balances water usage, nutrient uptake, and stomatal aperture.
CO2 — Carbon dioxide is used by plants, in conjunction with sunlight, to create oxygen and glucose, the basic energy source for plant growth. This makes it an integral environmental component in hydroponics gardening systems.
The carbon dioxide levels in the atmosphere surrounding hydroponically grown plants are directly correlated to their growth rates so monitoring the levels is essential. Normal atmospheric levels of CO2 hover around 400pm (with a range of 300 – 500 ppm), establishing a minimum threshold for good plant growth. Levels below 350 will result in a reduction At levels of 1200 t0 1500 ppm CO2, growth rates are increased significantly and may be seen at some of the highest
possible levels. It’s important though to note that at higher CO2, there may be a corresponding increase in temperature that needs to be addressed.
Air circulation — Stagnant, unmoving air Indoor growing systems are not exempt from insect infiltration. One of the best wants to combat insects within a given space is make sure there is constant air circulation. Don’t point circulating fans directly at plants as this may cause them to dry out prematurely, but you want to make sure the fans are providing enough air the leaves on the plant being grown are always slightly moving. A gentle breeze will hinder fungus gnats and spider mites.
Plant Essential Nutrients
The theory of plant essential nutrients is a fundamental aspect of plant nutrition today. No matter the plant, there are certain nutrients needed for basic functions and growth. These nutrients are considered plant essential and have specific roles within the plant. If any of the nutrients are deficient plant growth will be affected in some capacity.
Plant essential nutrients are classified as either macronutrients or micronutrients, based upon the relative concentration within plant tissue. Regardless of their concentration within the plant, they are all equally important.
Found in larger amounts within the plants, macronutrients are often involved in major plant process such as photosynthesis or are key structural components at the cellular level. Plant essential macronutrients include nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.
Nitrogen is considered the most key nutrient needed for plant growth. Its main responsibility in the plant is regulating vegetative growth. Nitrogen is assimilated into amino acids, the building blocks of protein, it is a major component of chlorophyll, and it is necessary for many of the plant’s enzymatic reactions.
Phosphorus is a structural component in DNA and RNA and is needed for root growth and flowering.
Potassium isn’t a component of any plant parts, but functions by activating the enzymatic reactions that occur, making it imperative for the overall health of the plant.
Calcium holds together cell walls through the formation of calcium pectate, a pectin fiber. When deficient, new tissues exhibit distorted growth because of improper cell wall formation.
Magnesium is needed for many enzymes within the plant to function properly but its most important function is as the central, structural molecule in chlorophyll. Without chlorophyll, plants cannot photosynthesize.
Sulfur is only required within plants in small amounts, but that doesn’t make it any less important than the other macronutrients. Through metabolic processes, plants break down sulfur into forms used to build organic molecules such as vitamins and odoriferous compounds in onions and garlic.
The plant essential micronutrients are needed in much smaller quantities within plants, but their functions are just as critical as the macronutrients. Many of them function as activators of enzymatic reactions and include iron, manganese, copper, molybdenum, zinc, nickel, boron, and chlorine.
Even though these nutrients are needed in much smaller quantities, it’s important your hydroponics nutrient solution contains the correct ratio of micronutrients for plant growth.
Configuring a Hydroponics Gardening System
When setting up either a personal/small scale or larger, commercial hydroponics system, the first consideration to think about is whether to build a system piece by piece or purchase one that is prebuilt. Along with that comes the decision on whether to run a grow system in a grow tent or build a dedicated grow room.
For gardeners that are just starting or those who are looking at smaller systems, many prefer the simplicity of buying a prefabricated system that is already pieced together for them. Buying prebuilt systems takes the guesswork out of deciding on the components needed. Hydroponic gardening equipment is readily available online through sites such as Hydro Emporium; with many different kits available to meet the needs of new or inexperienced growers.
On the other hand, building a hydroponics system from the ground up allows growers to create a system that meets their needs specifically. This can also be a cheaper route, albeit more time consuming because of needing to decide on individual components. There are many resources available providing instructions on how to build simple, beginner systems.
No matter the type of system wanted, or the space available, every hydroponic system needs a quality water source to prepare the nutrient solution, and some sort of reservoir to contain the solution. Systems that do not have access to natural light will need artificial light sources. To make sure a system is operating at its optimal potential you may need some exhaust fans, box or oscillating fans to move air around, and equipment to test or monitor the pH of the nutrient solution, thermometers to check temperatures, a hygrometer to measure relative humidity, and a carbon dioxide monito
Nutrient Solution Elements
One of the most important aspects of a hydroponics gardening system is providing a correctly mixed nutrient solution to plants. To mix the correct hydroponics nutrient solution for a growing system, it’s important to understand the impact water quality plays on the solution, what options are available for fertilizer sources, and why parameters such as electrical conductivity, pH, and solution temperature are important. Awareness of these concepts provides the foundation to manage a hydroponics system successfully.
Since hydroponics gardening revolves around providing nutrients to plants through a water source access to a clean, consistent water supply is yet another crucial aspect of a successful growing setup. A lack of water or poor quality water will hinder plant growth from the beginning, making it extremely difficult to maintain plant growth and the nutrient cycling that needs to occur.
The most cost-effective water source to use is what comes from the taps in the growing area, but this might not always be the best-suited water for plants. Water containing high levels of dissolved solids, e.g. “hard water”, can create extraneous problems for a grower. The excess amounts of bicarbonates found in the water need to be neutralized before running it through the system to reduce the pH level. This is typically done by adding phosphoric acid; the problem is when adding enough to bring the pH to an appropriate level, the phosphorus level of the water often becomes high, creating other problems.
In areas of hard water, growers often choose to collect rainwater to use, they purchase purified water or install a reverse osmosis filtration system to reduce the dissolved solids. Never use mineral or spring water as it can unbalance the nutrients in the hydroponics system or potentially be toxic to plants.
There are many fertilizer sources on the market that will provide the plant essential macronutrients and micronutrients needed to mix a perfect hydroponics nutrient solution. When it comes to choosing what sources to use there are different options to choose from, depending on personal preference.
Conventional versus Organic Fertilizers
Conventional/inorganic fertilizers are made completely, or sometimes partially, from synthetic, manmade materials. These inorganic fertilizers contain nutrients that are quickly available for the plants; quickly available nutrients mean plant deficiencies are fixed more rapidly, minimizing long-term effects. Inorganic fertilizers are cheaper to buy, and readily available for purchase.
Organic fertilizers are made from natural ingredients. They consist of the broken down remains of organisms or are a byproduct (i.e. waste) of the organisms themselves. The downsides to
organic fertilizers are a higher price tag, and nutrients are more slowly available for plant uptake after application.
Wet or Dry Fertilizers
Fertilizers come in either a granular or liquid form, both have their pros and cons.
Dry fertilizers are more economical to purchase and ship because their formulations don’t contain water. They have a longer shelf life and can be purchased in bulk quantities. Many commercial growers opt for powder or granular fertilizers due to cost efficiency.
Liquid fertilizer sources are popular with new growers. They are easier to work with, but have a shorter shelf life and are more expensive to purchase.
- Part or Multi-Part
Fertilizers can be purchased as a “1-part” system that contains all of the nutrients needed in a single formulation or they can be purchased as a “multi-part”, meaning you may need to be two, three, or four different nutrient mixes to create a single solution.
New hydroponics growers like the ease and convenience of buying 1-part mixes that contain all of the nutrients they need for a solution. The drawback with using a single nutrient mix is the resulting nutrient solution cannot be tailored to the developmental stage of your plants, and maximum growth may not be obtained.
As growers become more experienced they often switch to a 2-part or 3-part system. These multi-part systems more precise customization of the nutrient ratio, to correlate with fluctuating plant needs, resulting in better growth.
Whether synthetic or organic nutrient sources are chosen, wet or dry fertilizers are used, or what kind of formulation is selected, it is imperative to look for products marketed specifically towards hydroponics systems. Fertilizers made for soil-based systems are not formulated to provide the same levels of nutrients, especially micronutrients and can result in plant deficiencies.
Solution Electrical Conductivity (EC)
Water, in its pure form, without any additives such as distilled water or reverse osmosis water, is a poor conductor of electricity. But as mineral salts in the forms of cations (positively charged ions) and anions (negatively charged ions) are mixed into water, a solution is formed. These salts will allow electricity to move through the solution, a capacity measured as electrical conductivity (EC).
The higher the concentration of solute (i.e. salts) in a solution, the greater the solution’s ability to conduct electricity.
The nutrients used to formulate a conventional hydroponic nutrient solution are mineral salts and the same concepts of electrical conductivity apply. Higher salt concentrations equate to a higher EC. By measuring the EC of a nutrient solution you can gauge the nutrient solution strength. Unfortunately, measuring the EC isn’t an accurate tool when using organic fertilizers; the components used in them don’t conduct electricity like conventional mineral salts.
As a grower, it’s important to check the EC of the nutrient solution on a regular basis. Levels that are too high or too low can both negatively impact plant growth and require adjusting.
If the temperature of the growing environment exceeds the preferred 75°, plants will draw water out of the root zone without absorbing nutrients, to try to remedy drought stress. This will cause the salt concentration to increase and the EC to rise. Water will need to be added to dilute the nutrient solution to a more appropriate level.
In certain plant growth cycles, especially periods of heavy flowering or fruiting, plants will absorb more nutrients from the solution and leave the water behind. This dilutes the concentration of the nutrient solution and the EC will drop, signifying a drop in solution strength. More fertilizers should be added to raise the EC to optimal levels.
The pH of a solution is simply a measurement of how acidic or basic/alkaline the solution is and is calculated based upon the number of hydrogen ions it contains. Solution pH is an important tool to growers as it gives an indication of how the water used to make a nutrition solution has been changed chemically. It also indicates the availability of plant essential nutrients found in the solution.
pH — the potential of hydrogen — measures the concentration of positively charged hydrogen ions (H+) and negatively charges hydroxyl ions (OH-). A higher degree of positively charged hydrogen ions creates a solution that is more acidic; more negatively charged hydroxyl ions produces a solution that is less acidic, or basic.
Acidity/alkalinity is measured on a scale ranging from 1- 14. Solutions with a pH of 0 – 2 are strongly acidic, a pH of 3 – 5 is weakly acidic, a solution with a pH 6 – 8, a pH of 9 – 11 is weakly basic, and 12 – 14 is strongly basic. pH is an algorithmic scale; values increase or decrease by a factor of ten when there is a change in one full unit.
If the pH of the hydroponics nutrient solution is either too acidic or too basic, the ability for plants to absorb nutrients is significantly influenced, depending upon the hydrogen ion concentration and nutrient interactions. At either end of the pH scale the plant essential macronutrients — those needed in larger amounts for plant metabolic processes — become tied up, making them difficult for the plant to absorb; the micronutrients needed become more available at these extremes, potentially becoming toxic to plants due to their abundance.
Therefore, when growing plants hydroponically, monitoring the pH of the nutrient solution is vital to ensure nutrient availability isn’t compromised. It’s imperative as a hydroponics grower to continuously monitor the solution pH, keeping it between 5.5 and 6.5 for optimal nutrient availability.
Not to be overlooked, or considered unimportant, the temperature of the nutrient solution directly affects plant growth, root health, and dissolved oxygen content.
Nutrient absorption is controlled by processes within the roots since plants cannot regular temperatures themselves they simply adapt to environmental changes.
Lower solution temperatures correlate to a decrease in plant growth, if not a complete standstill. Roots produce a phytohormone, auxin, that is responsible for cell elongation, i.e. growth. At cold temperatures, auxin transport out of the roots slows, slowing cellular growth.
As temperature increases, dissolved oxygen decreases, but root respiration rates increase in conjunction, thus increasing the need for higher oxygen levels.
Higher temperatures also increase microorganism activity/metabolism and an increased prevalence of diseases such as pythium and other infections. This can be combatted with silicate additions, UV filtration, and increased oxygenation.
There isn’t a specific, concise range of nutrient solution temperatures that work across the board for all hydroponically grown plants. Temperatures are dependent on the plant varietal grown, and its current growth or developmental stage. Keeping your solution reservoir between 63 and 72°F will meet the growing needs of most plants. Another over 85 severely lacks oxygen and can damage plant roots. Most plants prefer a warmer nutrient solution during germination, propagation, and early vegetative growth. As they mature the temperature can be dropped, providing more oxygen for increased respiration rates.
Oxygen starvation symptoms are very general and may be hard as a grower to notice. Wilting of plants during the warmest/brightest part of the day is the first sign. Low oxygen reduces the permeability of roots to water causing a buildup of toxins. Stress response (wilting) incurs photosynthesis and carbohydrate transfer decreases, reducing plant growth.
Some cool-season crops such as lettuces and carrots growth the best with solution temperatures around 68-70°F; cannabis prefers solution temperatures ranging from 60-75°F depending on the stage of plant growth;
If higher nutrient solution temperatures are utilized, keep solution aerated with an air stone.
Commented : Add technical info
Supplemental lighting is a critical aspect of hydroponics growing, especially if using an indoor grow tent. Grow rooms may have windows where natural light is allowed to filter in but plants still require supplemental lighting for vigorous growth.
There are many different grow lights available for purchase, varying in price and function. To help choose lighting appropriate for your setup it’s important to understand the following basic concepts about grow lights.
After choosing which hydroponics system (active or passive, recovery or non-recovery) to employ in a grow, and deciding on a light set up, a grower then needs to determine the growing substrate best suited for their system configuration.
Choosing a growing substrate is an important consideration that needs to be made when setting up a hydroponics system. There are many different options available and what works best depends on the kind of hydroponics system implemented, the plants being grown, and even personal preference to an extent.
Unless using a deep water culture system — where plants are suspended by platforms and float on top of the nutrient solution — the growing substrate has a critical function. Plants need a media in which to anchor their roots, which will in turn help to support them as they grow. In some cases too the substrate will retain some moisture from the nutrient solution, fostering healthier plants.
While they are many options available, the most important aspect is the media used allows oxygen and water to reach the roots while securing the plant.
- Coconut coir is similar to peat moss and can hold approximately 8-10 times its weight in water. It is composed of the brown and white fibers found between the shell and the outer coating of a coconut seed. Coconut husks are soaked in water to remove the coir, and then the coir is allowed to dry and formed into bales.
It is the substrate type that most closely resembles soil, making it a commonly used product in hydroponics gardening systems, especially those growing cannabis. Coconut coir also has many other benefits: it is a renewable resource, it has a high cation exchange capacity, it resists compaction and decomposition, it has a pH closer to ideal, neutral conditions (5.2 – 6.8 typically), it promotes the growth of beneficial bacteria due to the presence of lignins, it is rich in hormones and bio-stimulants to promote plant growth, and depending on the source it contains plant essential nutrients such as potassium, iron, copper, manganese, and zinc.
- Peat moss is popular as a growing hydroponics substrate in some countries because of its low cost and high availability. Peat moss and other peat materials form due to the accumulation of decaying plant materials in areas such as bogs that drain poorly.
Sphagnum moss is the most commonly used form of peat moss; it is light in nature and can retain 10 to 20 times its weight in water while simultaneously draining well.
Fungistatic properties inhibit the growth of fungi too.
Drawbacks to using peat moss relate to its organic nature: a naturally low pH requires amelioration before it is suitable for use in a hydroponics gardening system, and its
decaying organic matter creates a media that is chemically unstable as it continues to decompose.
It is most commonly used in growing systems that contain acid-loving plants such as strawberries, tomatoes, acid-loving ornamentals, and when starting seeds because of its sterile nature.
- Rockwool cubes are an excellent substrate choice in hydroponics gardening, especially when cultivating cannabis. They are a dense mat of natural fibers that have been spun together: basalt rock and chalk are mixed together and then melted at a high temperature to form a lava; the lava is then blown into a spinning chamber to create long, intertwined fibers of an inert nature. After the fibers are spun, they are mixed with a binding agent to hold them together and pressed into large mats. The mats are then cut into various sized slabs and cubes and sold as a hydroponics substrate.
When the fibers are spun in the spinning chamber a structure is created that is perfectly suited to retain water while holding more oxygen than typical soil-less mediums. It is a mainstay media for commercial tomato growers, especially those implementing a drip irrigation system. Due to the chemically and biologically inert nature, rockwool cubes are popular in systems regardless of the growing stage of plants: starting seeds, cloning plants, all the way through harvest.
The one drawback to rockwool cubes is the pH must be adjusted before they can be placed in a system. During the manufacturing process, an abundance of calcium carbonate (lime) is deposited on the fibers; calcium carbonate naturally neutralizes hydroxyl ions, reducing the acidity and raising the pH of the substrate.
- Perlite is a silica-based mineral with volcanic origins. To be used as a growing media, high-grade materials are crushed and then heated until the internal water is vaporized, creating a light, airy substance. Perlite is excellent at increasing aeration and drainage because of its light, airy texture.
There are many advantages to using perlite as a hydroponics growing substrate: it has a neutral pH level, it takes on the pH of the nutrient solution, there is an abundant supply, it is easy to recycle, and it doesn’t hold onto nutrients like other substrates making it easy to rinse off and reuse in another grow. Perlite was one of the first reliable substrates used extensively in hydroponics systems.
Growers do need to wash perlite before use — albeit a messy process — to reduce the amount of dust moving through a hydroponics system.
- Vermiculite is formed from mica, another silicate mineral, that has a distinctive layered structure. Massive heat is applied to the mineral causing the layers of thin plates to
expand into accordion-like structures. The expanded particles have a very high water holding capacity and help to improve structure and drainage.
This high water holding capacity acts as a disadvantage to solely using vermiculite as a growing media. Holding on to high levels of water pushes oxygen out of the pore spaces between particles, and plant suffocating may occur. Most growers opt to use a 50:50 vermiculite and perlite mix to avoid low oxygen levels.
- Expandable clay pellets are typically used to increase the large pore space in a potting media, improving drainage and aeration by reducing the water holding capacity. Montmorillonite clay minerals are heated to a high temperature creating pottery like particles. The pellets are typically the size of marbles but can be purchased in a variety of sizes to accommodate the type of plants being grown.
This substrate is one of the best-known products in the cannabis industry and is used in many hydroponics growing systems. The large pore space created between the roots allows for a high degree of oxygenation; irrigation scheduling can be more continuous than other substrates, providing frequent feedings that promote a healthy, vigorous root system. In turn, plants grow very quickly and flower abundantly.
- Rock can be a viable option to use for a substrate in hydroponics systems, depending on the system you choose to use. It is easy to come by and if using a passive system such as ebb and flow where a substantial amount of substrate is needed it is quite cost effective. Pea gravel, lava rock, and river rock are good choices but care needs to be taken as lights/sunlight can warm the rock, in turn raising the temperature of the nutrient solution.
- Commercial potting mixes aren’t used very often in hydroponics systems, as the purpose is to grow plants without soil. However, some commercial mixes are a combination of “soilless” materials made with peat moss or coconut coir, perlite and vermiculite. This can be an inexpensive way for beginners to get a system up and running with fewer costs.
Since these mixes will soak up some of the nutrient solution, and hold on the nutrients, specific nutrient formulations have been developed for this system of gardening.
Setting up a Grow Tent or Grow Room
When growing indoors, there are many benefits to creating a dedicated space for your hydroponics gardening. Some growers choose to opt for a smaller grow tent, while others will create a full-fledged growing room for the gardening. Both options have similar benefits, and choosing the best one will depend on the operating you are running and its scale.
Benefits of an Enclosed Grow Tent or Grow Room
Energy efficiency — Creating a space with definitive boundaries allows the grower to carefully control the microenvironment within the grow tent or grow room. In turn, they are only lighting, heating, cooling, and ventilating that given area, maximizing the resources they are utilizing. This allows for better energy use and lower operating costs.
Optimal lighting — The insides of growing enclosures are constructed with a reflective material that diffuses and reflects light back towards plants, maximizing light intensity. Fully utilizing the light sources within the grow tent or grow room not only benefits the plants but also saves energy and reduces overall operating costs for a hydroponics grower.
Continuous ventilation — Having a dedicated, enclosed space for a hydroponics gardening system allows the grower to incorporate proper ventilation into the design. Continuous air movement through plants will help to circulate warm air caused by grow lights, distribute carbon dioxide through the plant canopy, strengthen plant stems, and reduce the incidence of insect pests.
Lower pest problems — ask any gardener/grower and they will tell you one of their biggest headaches when trying to grow plants is keeping insect pests at bay. Having an indoor grow tent or grow room for your hydroponics garden will drastically decrease the number of pests in your plants, especially if you keep doors securely closed.
Deciding on a Grow Tent or Grow Room
Different growing situations warrant different hydroponics gardening setups. When weighing the options between setting up a grow tent or building a grow room, evaluate the following considerations.
Growing plants hydroponically, indoors, can benefit immensely from setting up a grow tent to house the system. A grow tent is a good option when working with a small growing operation that doesn’t need a large amount of space or a great deal of ventilation; grow tents are also cheaper and can be taken apart and moved, a benefit for beginning growers or growers working with a rented space.
If the intent is to create a sizable hydroponics garden it would be better to build an indoor grow room, or convert an existing room into one if space allows it. While the initial cost outlay is higher than associated with a grow tent the environment variables are easier to maintain in a larger space.
Constructing an Indoor Growing Space
Commented : Rework this section, so that it is applicable to both tents and rooms.
Building a grow tent isn’t a difficult process, but it’s important to follow some steps in a specified order to get the best possible finished product.
- Gather all the supplies and any tools needed — Like any other project, it’s best to start off by having everything you need pulled together. Read through all of the instructions for the tent, lighting, ventilation, etc. and make sure you have all the tools you’ll need — screwdrivers, wire cutters, a box cutter or scissors — and any extra parts that didn’t come included. Don’t forget that you’ll need a power strip with a surge protector, perhaps a humidifier (if you live in a dry climate and need to increase the relative humidity), and it’s never a bad thing to have a roll of duct tape handy.
- Assemble the grow tent — Tents can be purchased in many different sizes with them typically being either square or rectangular to make them easier to fit modularly into a space. One key thing though is before you even begin to assemble a tent, double check the final location to ensure it will actually fit in the space.
- Construct the outer frame — Start off by unpacking all of the pieces, laying them out, and making sure everything was included in the package. Assemble the frame per the instructions and move the frame to its final location. Remember your plants need water and there is a chance this water can splash or spill onto the flooring. If you’re going to be placing it on a carpeted area protect the carpet with some sort of mats or plastic.
- Cover the frame with cloth — Once the frame is constructed and set in its place, it’s time to add the cloth covering. Most tents are constructed or lightweight nylon or a heavier canvas depending on the system purchased. Check to make sure the zippers work freely and all seams are sewn tightly without any defects. Sometimes it takes a little finesse to get the cloth securely over the frame.
- Install grow lights — Lighting is one of the most critical components of growing plants indoors. If the lights/lamps chosen are inadequate the plants will falter and struggle to grow; if the lights are too big for the system, they will generate too much heat that will need to be controlled. Consider installing a pulley system to allow you to easily adjust the lighting height as plants grow.
- Set up holders — Most lights will come with mounting hardware to attach lighting to the crossbars of the frame. Follow manufacturer’s instructions to hang lighting at the appropriate heights for the lamps used and plant needs.
- Attach hood — After the mounting hardware is secure, attach the lighting hoods to direct the light emitted downwards towards the plants.
- Organize wiring — Bundle all of the wirings together and make sure it is safely out of the way of the water, to prevent any electrical hazards. Then run all of the cords out of the grow tent through the closest power cord hole.
- Determine ventilation setup — Determine the best placement for the fan and carbon filter. Optimally, it is recommended that both the fan and filter to be hung inside the tent. Hanging them from the frame, closer to the top of the tent is ideal because it maximizes your growing footprint, removes the hottest air that rises to the top of the tent, and increases the odor removal effectiveness.
- Install ventilation — After figuring out the best place(s) to have the filter and fan, it’s time for installation. Start by hanging the carbon filter from one of the tent’s crossbars using the hanging equipment provided. Then hang the exhaust fan so the intake is pointed towards the carbon filter and the exhaust is directed towards the grow tent ventilation opening. Measure the distance between the carbon filter flange and the exhaust fan intake, then using the box cutter and wire cutters, cut ducting at the desired length. Install ducting between the filter and the fan, and then from the fan exhaust through to the ventilation opening in the tent. Run power cords through the nearest power cord hole in the tent.
- Hang temperature gauge — In order to keep an eye on the environmental conditions within the tent, you need equipment to monitor the temperature, humidity, etc. It’s best to install all of your monitoring equipment level with the plants you will be growing. If you mount it too high or too low it won’t provide an accurate reflection of the growing zone and your plants may suffer.
- Configure timers — Set up the timers that control when your lights come on/off, and anything else that you plan to run independently.
- Perform a safety scan — Check to make sure your electrical connections are secure, cords are up off the floor where they could possibly get wet, and nothing else could be a safety hazard.
- Dial in the entire system — Now that you’ve got everything set up, it’s time to turn it all on and see how it works. This gives you the chance to work any kinks out and make sure everything is running correctly.
- Start growing — Now that the tent is fully constructed, and your entire system is running well, it’s time to add the plants and get started growing! After adding plants keep an eye on the levels inside the tent as the plants will affect humidity, temperature, CO2 levels, etc. You may need to tweak your environmental settings as time goes on.
Propagation of Hydroponics Plants
Unlike conventional gardening methods most hydroponic growers choose to start their plants from seed or through propagation techniques such as cloning instead of buying plantlets to use. Purchasing plantlets from a nursery or garden center limits the varieties available to be grown, has the potential to introduce pests or diseases into the hydroponics system, and if using a soilless system all the soil must be washed from the roots before transferring them into the setup.
While it is more time consuming to grow from seeds or propagate from existing plants the negatives benefits of buying plantlets far outweigh the additional time and effort.
After a hydroponics system is initially up and running it’s crucial to perform regular maintenance to ensure everything is running at an optimal level. While the maintenance needs are slightly different in hydroponics there isn’t any one aspect that is particularly difficult or challenging.
- Monitor solution EC, pH and temperature.
As mentioned before, making sure the nutrient solution is within optimal electrical conductivity, pH, and temperature is key to nutrient uptake and plant growth. Using an EC meter, a pH meter, and a thermometer these parameters should be monitored daily and adjusted if necessary.
- Check substrate pH.
Some types of growing media (coco coir, peat moss, and rockwool, specifically) have been buffered or ameliorated during the manufacturing process, to bring their pH to an appropriate level for plant growth and to resist changes in pH when an acid or alkali is introduced. Over time these added components leach out causing the substrate pH to drift back to its natural level and render nutrients unavailable for root uptake.
Checking the substrate pH periodically with a pH meter will indicate if the buffering capacity is decreasing and the substrate needs to be ameliorated to the correct pH level.
- Test leachate pH.
Measuring the pH of the leachate collected after plants have been fed, and observing any drift that occurs, gives the grower a good look at plant nutrient uptake. Nutrient solutions are made up of cations (positively charged ions) and anions (negatively charged ions) and are always balanced to have the same number of positively charged ions as negatively charged ones. As the plant absorbs nutrients from the solution, they will replace them with a corresponding ion (hydronium cation or hydroxide ion). This replacement will cause the pH to adjust up or down, giving an indication of what nutrients that plant is absorbing.
- Keep the system clean.
Remove decaying or diseased plant material and dispose of it properly to minimize the risk of pest problems, fungal diseases, or simply the spread of disease to other healthy plants.
- Check nozzles/drippers.
If using a drip or aeroponics system, over time mineral deposits from the nutrient solution can build up and clog the nozzles and drippers, affecting the output or ceasing flow completely. To circumvent this, keep extra parts on hand and regularly check the nozzles and drippers for build up. When mineral scale starts to clog openings, switch them out for a new, clean part and soak the clogged one in vinegar to remove the build- up.
- Change solution weekly.
Topping off the nutrient solution reservoir with water and adjusting the EC/pH needs to be done daily, but over time the solution becomes depleted of vital micronutrients and may incur bacterial growth. It’s recommended to empty the nutrient solution reservoir weekly, clean it out with a diluted bleach solution, and mix a new solution.
- Scout for pests/diseases.
As mentioned previously, the incidence of pests and diseases is generally decreased when gardening in an indoor, enclosed hydroponics space. Unfortunately, this doesn’t mean the problems are non-existent.
- Keep detailed records.
Create a written log to keep records of the entire hydroponics system. This can be done with a notebook and pen/pencil, one of many smartphone apps, or on a computer.
Having a well-documented record of the system, including problems and successes, allows the grower to go back and revisit what he/she did before in a certain situation.
Detail maintenance records, when nutrient solutions were changed and the exact amounts of nutrient mix added, how environmental changes impacted plant growth, what nutrient solution EC/pH/temperature worked best for specific developmental stages, daily CO2 and light levels.
Hydroponics gardening — gardening in soil-less systems — has many advantages over traditional gardening methods: faster plant growth and higher yields, year-round growing seasons, and decreased, more efficient use of inputs. These systems are intricate and to be successful the grower should understand the basic concepts of hydroponics gardening, why nutrients are important for plants, how to provide essential nutrients through nutrient solutions, and how to correctly manipulate and maintain the environmental conditions needed for growth, as well as the overall system in general.