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Fertilizing Cannabis Plants in a Hydroponic System

Fertilizing Cannabis Plants in a Hydroponic System

The United States continues to legalize the use of marijuana for medicinal and recreational use. As a result, more individuals are choosing to grow their own cannabis for personal consumption. There are a number of ways to grow this diverse plant, even in small spaces. One way that many people are choosing to grow their own supply is with the help of a hydroponic system.

What are the benefits of using a system of this type and how does one ensure the plants receive the nutrients they need?

Hydroponic systems are a great way to grow marijuana without the need for soil. Water-soluble fertilizers serve as the only source of nutrients for the plants. These systems supply oxygen and nutrients directly to the root of the plant and produce plants with bigger buds in less time.

One thing to know about a hydroponic weed system is that there is no buffer between the nutrients and the plant. As a result, any mistake can be disastrous to the crop. Why would someone choose to use a hydroponic system rather than simply growing their crop in soil? Read on to find out!

The Benefits of a Hydroponic System for Cannabis Growers

Cannabis growers choose a hydroponic system if they wish to have bigger yields. The growing time is much faster as well. The person growing the marijuana finds he or she has more control over the nutrients provided to the plant. In addition, plants can’t be starved of oxygen and, in fact, receive more oxygen at the roots where it is required.

These benefits are seen as the necessary amount of food is delivered directly to the roots of the plants. The plants do not have to search for it. Furthermore, the pH and fertility of soil can be difficult to measure. This issue is removed when a hydroponic system is used. This leads to the plants having the food they need to eat and grow bountifully.

Humans may water plants in the soil only to have the basic elements dissolve in the water before ever reaching the marijuana plant. As moisture remains present in a hydroponic system for an extended period of time, this is less of a concern.

Finally, pests are rarely an issue when cannabis is grown using a hydroponic system. The growing mediums used in the hydroponic system are inert and sterile. This means the environment is hygienic for both the plants and the grower.

The Drawbacks of Soil

When cannabis plants are placed in soil, they obtain the necessary nutrients through biological decomposition. As the soil breaks down organic matter, it turns it into nitrogen, potassium, and phosphorus salts. The plants then feed on these salts, doing so by absorbing the salts through the roots.

Cannabis plants need a well-balanced diet. As a result, all components in the soil need to be in perfect balance. Unfortunately, this is rarely the case. Organic matter may not be left on the soil’s surface, contamination remains an issue, and biological imbalances may be present. As a result, soil cannot produce the volume of nutrients needed for a good cannabis crop. This isn’t an issue when a hydroponic system is used.

Plant Composition

Marijuana plants are mostly water. In fact, 15 to 20 percent of the plant is carbon, oxygen, and hydrogen. The rest is water. The plants pull the carbon, oxygen, and hydrogen they need from the air and water. As a result, the plant’s atmosphere is what must be controlled to ensure the plant obtains what it needs. The grower is responsible for knowing what the plant needs to survive and thrive. One major benefit of a hydroponic system is that little water is lost to evaporation. This makes it the perfect choice for growing weed in areas where drought remains a problem, and this is only one of the benefits.

Fertilizing the Plants

Growers ultimately determine which nutrients their cannabis plants receive through the feeding solution. Rockwool by itself is not sufficient for the needs of the plant. In actuality, this substance is an inert growing medium. As a result, it doesn’t provide the plant with any nutrition and any mistakes that are made during the making of the feeding water could lead to disaster for the growing plant.

While plants don’t require soil to survive, certain elements are required. The macroelements needed for plant life are calcium (Ca), magnesium (Mg), nitrogen (N), phosphorus, (P), potassium (K), and sulfur (S). Microelements are also required for plant life, including boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn).

When using a hydroponic system, growers need to enrich the water with these nutrient salts. Doing so requires the right balance to be obtained for the plants being grown. Many people choose to use an all-purpose hydroponic nutrient solution, one that contains the microelements. However, there are advantages to adjusting the fertilizer based on the growing stage of the plant.

Knowing how to read a fertilizer label is of great importance. If the label says 15-15-15, it means the solution is made of 15 percent nitrogen, 15 percent phosphorus, and 15 percent potassium. In contrast, a 20-10-5 solution is made up of 20 percent nitrogen, 10 percent phosphorus and five percent potassium. The remaining solution is made up of trace elements and inert material. In the first example, 55 percent would be trace elements and inert material. In the second, it would be 65 percent.

When purchasing nutrients for a hydroponic system, pre-mixed solutions will be offered along with a powder that the grower mixes with water. Most men and women prefer the powder as it is much cheaper over time.

The Difference Between Hydroponics and Traditional Cannabis Growing Methods

When cannabis plants are grown out in the open, the soil determines the elements that are provided along with the age of the soil. Additionally, certain buffer capacity is built into the soil. The cannabis plant pulls the nutrients it needs from the soil while leaving the rest behind. They remain in the soil until they are needed, and the soil replenishes the nutrients over time. As a result, the grower has fewer decisions to make, and fewer mistakes will be made. This isn’t the case with a hydroponic system.

The grower must handle all aspects of feeding and watering the plants, and accuracy is critical at this time. Continuous monitoring is needed so adjustments can be made when called for, and the grower must be knowledgeable when it comes to knowing what the plant needs to thrive.

Hydroponic systems make use of a growing medium like Rockwool or coco coir in place of soil. To ensure the cannabis plants receive the sustenance they need, store-bought nutrients designed specifically for hydroponic systems must be obtained. These nutrients do not contain organic materials, as the minerals provide this material. When choosing a fertilizer, be sure to look for the optimum NPK ratios.

During the plant’s vegetative stage, high nitrogen and potassium are needed along with medium phosphorus. When it reaches the flowering stage, high potassium and phosphorus are required while the nitrogen needs to be lower. Additional micronutrients may also be found in these fertilizers, including boron, copper, iron, magnesium, manganese, and sulfur.

The pH levels in the system must be kept between 5.8 and 6.2 to ensure optimum bud growth. However, the strength of the fertilizing solution needs to be monitored to make certain it won’t exceed what the plants can reasonably handle.

Growers need to take into account the electrical conductivity, the parts per million (PPM), and the Total Dissolved Solids (TDS). This information is required to ensure the plant’s roots don’t burn and the crop isn’t starved. Sadly, this remains one of the most common challenges for people who choose to grow cannabis in a hydroponic system. For this reason, it is crucial to follow the manufacturer’s instructions when preparing the fertilizer.

Creating the Ideal Nutrient Mix

When temperatures drop below 80 degrees during the vegetative stage of growth, more nitrogen will be needed. Choose or create a solution with a 20-20-20, 23-19-17, or 12-6-6 blend. Any solution with similar proportions that contains trace elements will benefit the plants. However, if the temperature will remain higher than 80 degrees in the grow room, extra nitrogen isn’t required.

During the flowering stage, more phosphorus is required. This is true regardless of the room temperature. Choose a 15-30-15, 5-20-10, or 2-4-3 solution or something that is very similar in terms of the blend. Make certain the solution also contains trace elements.

Take care not to overfertilize the plants. Doing so could kill them. Although not providing enough fertilizer for the plants will slow their growth, they won’t be harmed. When mixing the solution, be sure to follow the directions on the package. If there is any uncertainty, less is better.

Water will evaporate from the system but at a slower rate than it would when the plants are being grown in soil. As this water evaporates, the level in the water reservoir drops. Add tap water only after it has been aged three days or longer. There is no need to add more nutrient solution to the reservoir when topping up the tank, although some growers choose to do so.

One thing to know when adding nutrients to the hydroponic system is to always add the mix to the water. Never add the water to the mix. When water is added to nutrients, the nutrients lock up and the plants could end up starving. Furthermore, monitor the pH and PPM of the water to make certain it is suitable for the plants.

When adding anything to the water, give it time to dissolve before taking a reading. If the nutrient has not fully dissolved, the reading may not be accurate. Use a separate bucket for mixing the nutrients and test the PPM first. Once this is correct, then the pH should be adjusted.

Ensuring the Nutrients Reach the Plants

Plant roots need to be submerged every twenty minutes or so. No grower wishes to have to handle this task manually, and a timer is of great help in ensuring the solution is delivered when needed. Once the roots have been submerged, the pump shuts down. If the process takes more than 20 minutes, the roots will grow longer as they attempt to find the source of the nutrients.

This can become a problem. There are times when the roots grow so long and so thick that the solution can no longer reach all the way up the grow cups. In addition, the root material may be ripped out and lead to one or more clogs in the system.

If the system becomes clogged by roots or other materials, the entire garden must be taken apart and cleaned. To prevent this from happening, examine the length of the roots every few weeks. This is of importance because the cups are difficult to remove as the roots anchor to the internal channel when they grow too long.

Keep the roots short enough that they do not touch the narrow point when the solution enters the cut holder. If the roots have become too long, a pair of scissors may be used to trim them. However, take care not to cut more than is required. Any solution that is lost during this process may be used for watering plants in your home or garden. Doing so allows these plants to benefit from the nutrients and grow at a more rapid rate.

Fixed Fertilizers

Hydroponic systems don’t make use of fixed fertilizers. In fact, when a grower is making use of Rockwool for the plants, the fertilizers and water are put directly on the plants. As a result, they must be quickly absorbed. Fixed fertilizers aren’t soluble enough for the plant to receive nutrition in a timely manner. In addition, if the fertilizer isn’t very soluble, blockages may occur in the water system. For this reason, liquid fertilizers tend to be the preferred choice of growers.

Liquid Fertilizers

What benefits do liquid fertilizers offer? First, they tend to be purer than their siblings and contain only what is needed for the plant to thrive. This ensures the plant receives what is required at that specific time. Some liquid fertilizers leave behind no residue, and the plants directly absorb the nutrition thanks to the fertilizer’s solubility in water.

However, liquid fertilizers need to be handled with care. They are a blend of nutritional elements essential to the plant. When these elements are combined with oxygen, water, and CO2, the plant is able to create the hormones, vitamins, and cornerstones needed to grow, produce flowers and become THC.

Are Organic Fertilizers Required?

Growers often assume organic fertilizers remain the best choice, but this is actually not the case. They are no healthier than chemical fertilizers, and all products of this type serve the same function. Biological fertilizers, as they are often called, contain a mix of organic compounds. These compounds, when viewed from a molecular standpoint, provide a chemical fingerprint for the fertilizer. Therefore, organic fertilizers are chemical just as other fertilizers are. The plant ultimately decides which substances are needed from the compound.

Which Fertilizers Should Be Used with Cannabis Plants?

Individuals new to cannabis growing often purchase a pre-packaged fertilizer. However, as the grower’s knowledge increases, he or she might wish to make their own solution and add various substances to the fertilizer to improve the yield. A number of substances may be used for this purpose.

Human Urine

Urine from a healthy human being is a great fertilizer for cannabis plants. Fresh urine from humans is high in nitrogen, a substance that serves as one of the key nutrients for cannabis plants. For individuals following the typical Western diet, the NPK ratio of urine is 11-1-2. Compare this to blood meal which has an NPK ratio of 12-2-1.

However, this does not mean men and women should be encouraged to urinate directly on the plants. Salt is removed from the body in urine, but too much sodium can be harmful to cannabis plants. Dilute the urine to a ratio of one part urine for every ten parts water. When using the urine on potted plants or seedlings, such as those being grown in a hydroponic system, the ratio should actually be 1:20.

Perlite and Vermiculite

Perlite and vermiculite are two substances that may benefit a marijuana crop. While both are sterile inorganic materials, they do look and act differently. Perlite is created by the heating of volcanic glass to a very high temperature. This process results in a substance that is porous and hard. In contrast, when mica is heated to an extremely high temperature, it creates vermiculite, which is a soft and spongy material.

To distinguish between the two, simply look at the color. In most cases, vermiculite is brown or tan while perlite is white. Vermiculite absorbs water and has a pH that is almost neutral. Perlite, on the other hand, traps water and has a pH that is slightly alkaline. While they are different, they are often sold together, as the combination of the two absorbs water up to four times its weight.

When used, the combination provides the plants with calcium, potassium, and magnesium, all substances cannabis plants need. Growers making use of a hydroponics system should use a fertilizer that includes 50 percent perlite and vermiculite and 50 percent peat moss and water.

Wood Ash

Growers who have a fireplace, wood stove, or outdoor fire pit and grow cannabis for personal consumption have an excellent fertilizer on hand. The ash from a wood fire contains potassium and lime that is perfect for cannabis plants. Lightly scatter these ashes over the plants or include them in a compost heap when growing the plants in soil. Be aware, however, that wet ash produces high amounts of lye and salt.

The type of wood burned plays a role in the number of nutrients available to the marijuana plants. Maple and oak, for instance, contain more nutrients than other wood species. One reason many traditional marijuana growers choose to use wood ash is it is a natural pesticide that keeps soft-bodied invertebrates away. However, this isn’t a concern for those who are growing their cannabis in a hydroponic system.

How Often Should the Fertilizer Be Changed?

Growers need to know how often to change the fertilizer. The nutrient solution must be changed at least once every 14 days. If the reservoir dries up, this task should be completed sooner. Whenever changing the fertilizer, be sure to clean the pumps and reservoir after discarding the old solution. Use hot water to remove any residue that has accumulated in the equipment.

When replacing this water after cleaning, use tap water that has been aged a minimum of three days or longer. Add the nutrient solution after adding the water. The cups and tubing for the plants only need to be cleaned when a new crop is started.

Tips for a Successful Crop

Don’t panic if yellow leaves appear at the base of the plant right before harvest time. This is normal. Nutrient burn does occur but does not mean the plant is a complete loss.

When using a store-bought solution, begin with half the recommended dose. Continue with this dose unless or until the plant shows signs of a nutritional deficiency. Different strains require different amounts, and this method helps to ensure the plant does not receive more than it needs.

If organic fertilizer is used, start with a small amount. Only increase the dose when needed. Many growers find a small dose is more than enough to provide the desired yield.

Keep learning. As more people begin growing cannabis, the knowledge base will increase. Learn from others and share what you know. Growers who do so find they get more from their hobby when they connect with others.

If you have been thinking about growing your own cannabis supply, now is the time to do so. Thanks to the many providers offering seeds and supplies necessary to achieve this goal, you’ll find you can have a crop growing in no time at all.

Once you feel confident growing this plant, don’t hesitate to try new things. With slight modifications to the fertilizer, the lights, the plant setup and more, you will find you can increase the yield and get more for your efforts. Starting with seeds from an online cannabis seed bank like will ensure a solid start to your personal growing experience!


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