Growing cannabis plants using hydroponics means you are growing without soil, but it doesn’t necessarily mean that you are growing plants without a soil replacement. While not strictly necessary it is usually advantageous to use some form of growing medium. One very good reason to use a growing medium in your hydroponics garden is to ensure that the roots of your plants are adequately supplied with oxygen. In a traditional garden plant roots gather oxygen from the air trapped in the soil. A growing medium serves the same purpose for plants grown with hydroponics. Growing media are designed to trap air that can then be processed by the plant roots.
Another reason for using a growing medium is to provide a food reserve for the plants. Like air, nutrients from the feeding solution are trapped in the pores of the growing medium and are then available to the plants if needed. This can help to prevent crop failures. Here’s a quick rundown of the kinds of media available to you when gardening without soil.
Types of Growing Media
Made from basalt rock and chalk, Rockwool is probably the most popular growing medium used by hydroponics gardeners. This porous material can trap large quantities of air and water at the same time.
Perlite and Vermiculite
Perlite is a pebbly volcanic rock that provides excellent drainage and aeration when used as a growing medium. It has a good drainage characteristic which means it does not hold much water and limited ability to trap nutrients. Vermiculite is a mineral that acts like a natural wick and is able to absorb large quantities of water. The combination of Perlite and Vermiculite is a natural for hydroponics system: one holds air and oxygen, the other holds water and nutrients.
Made from the outer husks of coconuts this growing medium is becoming increasingly popular with organic growers. Some hydroponics growers feel coconut fibres are superior to Rockwool in their ability to retain air and water.
Expanded Clay Pellets
This medium is made from baked clay. The pellets are porous and retain both air and water very well. They can be reused as long as they are first sterilized.
This is the same colored gravel that is used in fish tanks. The main reason for its popularity is expense as it is inexpensive compared to other growing media. The downside is that it does not hold water, and therefore plant nutrients, very well at all. If you choose to use aquarium gravel you will need a constant water supply for your plants to avoid root drying.
Hydroponic Nutrients – The Essential Elements
There are 17 essential elements needed for plant growth. Three of them (hydrogen, oxygen, and carbon) are non-mineral elements and are absorbed by plants through the air or water. The other 14 essential elements must be provided by the soil or fertilization. Since hydroponic gardening bypasses the soil, all 14 essential mineral elements must be furnished in the hydroponic nutrient solution.
These essential mineral elements are broken into two categories: macronutrients and micronutrients. The macronutrients are the nutrients used in higher concentrations relative to micronutrients which are absorbed in smaller amounts. When shopping around for hydroponic nutrients, a gardener will quickly notice three numbers on the nutrient solution’s label. These numbers represent the N-P-K values or ratios of nitrogen (N), phosphorus (P), and potassium (K) in that particular formula. Nitrogen, phosphorus, and potassium are the primary macronutrients. In other words, they are absorbed in higher ratios than any other essential mineral element. This is why it is important for fertilizer labels to disclose the N-P-K ratio. A closer look at all of the macronutrients found in hydroponic fertilizers will give growers a better understanding of how each element affects plant growth.
A basic component of proteins and chlorophyll, Nitrogen is the main nutrient responsible for vigorous growth and luscious green coloration.
Plays an important role in root stimulation and establishment for young plants. Phosphorus also promotes flowering, fruiting, ripening, and respiration.
Promotes movement of sugars and other nutrients (via osmosis). Potassium is directly linked to stem strength and rigidity. Potassium increases a plant’s overall resistance to cold, drought and pathogens. Much like phosphorus, potassium plays an intricate role in the formation of flower buds and fruiting/blooming processes.
Builds and becomes part of the cell walls. Calcium is vital to plant structure and strength and promotes growth of young shoots and roots. Calcium is needed for ripening and seed production.
Reinforces cell walls and is an important component of chlorophyll. Magnesium promotes the absorption of phosphorus, nitrogen, and sulfur. It also plays a vital role in the ripening of fruit and the germination of seeds.
Contributes to chlorophyll production and is a necessary component of several proteins, enzymes and vitamins. Sulfur aids the plant’s absorption of potassium, calcium, and magnesium.
Micronutrients, although absorbed in lower amounts than macronutrients, play an equally important role in overall plant health.
Involved in the stimulation of photosynthesis.
Assists in biochemical processes, including the manufacturing of chlorophyll. Iron also contributes to the formation of some enzymes and amino acids.
Essential for tissue growth within the plant. Promotes the absorption of water and helps regulate a plant’s metabolism. Boron also assists in the formation of fruit.
Plays an essential role in nitrogen assimilation and protein formation. Manganese can speed up a plant’s maturity and helps promote seed germination. It is also necessary for chlorophyll production.
Helps the development of enzymes and growth hormones.
Plays a role in chlorophyll production and helps activate various enzymes.
It is needed for the production of nitrogen-based proteins and is essential for nitrogen assimilation by plants.
Regulates mineral metabolism, enzyme activity and other metabolic processes in plants.
Hydroponic Base Nutrients
There are many choices and it can become overwhelming trying to choose a brand of hydroponic nutrients (fertilizers). The first thing a hydroponic horticulturist should do is choose a base nutrient formula. A base nutrient formula will contain all the essential mineral elements, therefore providing all elements necessary for plant growth. Depending on the manufacturer, the base nutrients may be a one, two, or three part formula. Regardless of how many parts it is all base nutrient formulas do the same thing: provide the plants with the essential mineral elements. A good hydroponic base nutrient is all that is needed to get started growing hydroponically.
Can I Use my Hydroponic Nutrients for Soil Gardening?
Hydroponic base nutrients are designed specifically for use in hydroponic systems. Although they can be used in a pinch to fertilize plants in soil containers, they are designed for hydroponics which means the ratio of some elements will differ from fertilizers designed specifically for soil.
pH in Hydroponics
In order for the plants to absorb the essential elements in a hydroponic system, the pH of the solution must be in a particular range. A pH of 5.5 – 6.0 is the desired range for most hydroponic systems. If the pH gets above or below that range, the plants will be unable to absorb certain nutrients. This will eventually lead to a deficiency. Hydroponic growers will need to have pH buffers (pH up and pH down) on hand to make adjustments when necessary.
Finding a hydroponic nutrient formula can be overwhelming for new growers. Just remember, a good base formula and pH buffers are all you need to get started. Once you feel comfortable with your base formula, you can begin experimenting with the plethora of hydroponic nutrient additives available at your local hydroponic retailer.
Hydroponics System Daily Maintenance Check List
Once a growing system is up-and-running, to successfully grow hydroponic plants, there are only a few tasks required. Check the system daily or every other day and do the following keeping in mind the 5 basic requirements of plants (light, water, nutrients, temperature and oxygen).
- Most plants love humidity so mist them continually and they will be happy.
- Watch the system and make sure it is performing properly. If it floods the plants and drains at a specific time – verify this. Small bits of growing medium can clog the tubing of a system in no time flat and either leave your plants ‘high and dry’ or continually flooded. This happened to me once.
- As your nutrient solution evaporates, add tap water to refill it to where it should be. Do not ever add a touch more of nutrient powder to replace what you think has been used up. This is a really good way to kill your plants.
- Keep an eye out for pests and disease as well as nutritional deficiencies.
- Take care of any problems as fast as possible or they will grow into large problems faster than you will believe.
- Take a look at the plants. Are they wilting and is the growing medium completely dry? Or is it continually soaked? Adjust the amount of nutrient solution accordingly (this is for systems that periodically receive nutrient solution most likely through a timer).
- Dead growth saps the energy of a plant and can be a good beginning for a disease or pest problem so keep the dead matter pruned.
- Keep track of the temperature if you are in a greenhouse and ventilate if necessary by opening doors, windows and turning on a fan.
- In an enclosed area like a greenhouse, let some bugs and breezes get in. This not only helps with pollination but some bugs will actually protect your plants by eating the bad ones.
- Learn to identify the good vs. bad bugs. Dragonflies, spiders and ‘daddy long legs’ are good to have around – they eat the bad bugs so encourage them. I personally love dragonflies – I’ve seen them dive-bomb horse flies and moose flies and eat them.
- Keep a log. What becomes second nature to you now will probably be completely forgotten in a few months so write it down.
I know this seems like a lot of effort but once you get a routine down you may not need more than a few minutes a day to perform these tasks. Keep up the vigilance and you will grow hydroponic plants that are healthy and you will be amply rewarded with a large amount of vegetables and herbs.
Choosing a Hydroponic Fertilizer is Kind of Like Buying a Car
Upon entering a hydroponic retailer, a consumer will quickly notice the seemingly countless options available. There are many choices when it comes to choosing a brand of hydroponic nutrients (fertilizers) and this can be overwhelming for a novice hydroponic enthusiast. Choosing a hydroponic fertilizer is kind of like buying a car. There are many options but, at the end of the day, they all get you from point A to point B.
The base nutrients of a hydroponic nutrient solution do just that, get your plants from the beginning to the end. The base nutrients will contain all the mineral essential elements and will provide all that is necessary for plant growth. The essential elements found in hydroponic nutrients can be derived from a variety of sources. The varying sources will affect the formula’s stability. This leads to different types of formulas for the horticulturist to choose from. Typically speaking, there are three types of formulas produced by manufacturers of hydroponic nutrients. One-part formulas (stand-alone grow and bloom), two-part formulas (grow A and B and bloom A and B), and three-part formulas (micro, grow and bloom). A hydroponic grower will usually first choose from a one-part, two-part or three-part formula and then choose which brand of fertilizer he or she wishes to use.
A one-part formula consists of one individual grow formula and, if it is for growing a plant that produces fruit or flowers, one individual bloom formula. One-part formulas are great for beginner hydroponic growers as they only require the dosing and mixing of one product. The stage of growth of the plant(s) will determine if the gardener uses the grow or the bloom formulation. The type of crop and stage of growth will determine the dilution rate for the particular product. One-part formulas will contain all of the essential elements needed to sustain plant health. However, one-part formulas will usually contain less than optimal levels of some of the essential elements in order to make the overall formula stable. For example, many one-part formulas contain only small amounts of calcium and rely on calcium contained within the grower’s water to make up the difference. Horticulturists using one-part formulas may, in some cases, need to supplement additional sources of certain essential elements.
A two-part formula consists of two parts for both the grow and the bloom stages of plant growth. In other words, during the vegetative stage of growth, both a grow A and a grow B formula will be required. If the horticulturist is growing a particular plant variety with a fruiting or flowering stage of growth, he or she will be required to use both a bloom A and a bloom B during that period. Two-part formulas offer an advantage as they are able to separate some of the elements that would otherwise create an unstable formula when mixed in the concentrated forms. More specifically, two-part formulas are able to separate particular compounds containing concentrated calcium and phosphorus which could react poorly when mixed. A two-part formula allows the horticulturist to dilute the concentrated calcium before adding the phosphorus. This is why the part A of a two-part formula will usually contain the calcium. Generally speaking, two-part formulas can contain a higher concentration of calcium and a more ideal ratio of all the essential elements than a one-part formula.
A three-part formula consists of separate micro, grow and bloom formulas. Unlike the one-part and two-part formulas where the “grow” is used exclusively in the vegetative stage and the “bloom” is used exclusively in the fruiting or flowering stage, three-part formulas use all three parts throughout the entire life cycle of the plants. The ratio of the three parts (micro, grow, and bloom) will change depending on the particular dietary needs of the plant and the stage of growth. For example, a pepper plant in its vegetative stage will receive different ratios of each of the three parts than a pepper plant when it is producing peppers. As the names suggest, the “micro” contains most of the micronutrients (and usually the calcium), the “grow” contains nutrients more specific to growth and the “bloom” contains nutrients more specific to blooming. Although growers will use all three parts throughout the plant’s life cycle, they will typically use a higher ratio of “grow” during the vegetative stage and a higher ratio of “bloom” during the fruiting or flowering stage. A three-part formula offers heightened control to the horticulturist and gives the ability to more quickly correct deficiencies.
After a hydroponic gardener has established an effective base fertilizer program, he or she can begin to experiment with the various nutrient additives available on the market. Micronutrient supplements, carbohydrate formulas, enzyme formulas, plant vitamins, plant hormones and beneficial microorganisms are just some of the options a hydroponic gardener can experiment with. Each garden is different and the best way to determine if a nutrient additive is truly beneficial is by way of experimentation.