How To Grow The Best Cannabis

How To Grow The Best Cannabis

How To Best Grow Legal Cannabis In The USA

By far and away the best way to grow legal cannabis in the USA is to do it in a state where it has been legalized. Prison time is not conducive to to growing a booming business. Well… duuuuhhhh! Seriously, there are many “best practices” when it comes to growing cannabis successfully and profitably. However, we are here to discuss what growers can do to increase their yields and profitability by growing cannabis with high quality water.

Not surprisingly, water is frequently overlooked as a critical component of growing cannabis. After all, many people feel that if water is safe to drink, it must be safe for growing plants. Before we can decide how to treat the water, we must first understand the role that water plays in growing any plant, and especially cannabis. Cannabis is approximately ninety percent (90%) water, so it would be difficult to overstate the important role water serves in growing the plant.

I can’t write it any better than the Royal Queen Seeds Blog, so here is how they phrased it:

“Water transports nutrients, gives the plant its stiffness and lushness or "turgor," and plays a major part in photosynthesis. During the day, water travels up the stem to the leaves where it evaporates through tiny holes called stomata and is then exchanged for carbon dioxide. This is called transpiration. The exchanged carbon dioxide is then used to in combination with light to create sugars which are the plant’s food; this is called photosynthesis.”

Poor water quality means that these natural processes may be impeded greatly or even stopped altogether which greatly affects the production, which ultimately impacts the bottom line profitability. Let’s look at some of the chief water quality problems facing cannabis growers:

Chemicals & Heavy Metals

Often overlooked, chemicals and heavy metals are almost always detrimental to any plant, especially cannabis, as well as people who use the product. These include arsenic, nitrates, nitrites, chlorine, chloramine, PCB, TCE, dioxin, glyphosate, lead, cadminum, mercury, chromium, and many, many others. Heavy metals accumulate in parts of the body, and are not easily eliminated. Arsenic contaminantion is much more common than most people believe and small amounts can be deadly. Plants naturally absorb arsenic and store it in their tissues.

When nitrates enter a human body, some of them can change into nitrites. The combination of nitrite with specific organics can produce substances with great carcinogenic potential, known as nitrosamines. Other chemicals, even chlorine and chloramine (produced by municiplaities by the addition of ammonia to chlorine to stabilize it) can greatly impede the growth of plants.

SOLUTION: A successful water treatment system will usually include carbon filtration to reduce or remove chemicals and heavy metals. The systems should also include catalytic carbon which successully removes chloramine added by municiplaities. Many growers utilize two columns of carbon:

#1 – Coconut shell granular activated carbon (GAC); and
#2 – Coconut shell catalytic granular activated carbon

This two-step method removes the widest spectrum of chemicals and other heavy metals, but is usually just a part of a larger system.

UV SystemBacteria

Water, even city water, can contain bacteria which can be deadly to humans as well as very detrimental to the cannabis plant. Healthy plants (i.e., plants not subject to bacteria in the water supply) can produce up to 35% more than plants subjected to bacteria. Even if your water test shows no bacterial contaminantion, you still need to disinfect due to potential contaminantion on any given day.

SOLUTION: Ultraviolet Disinfection (“UV”) and Quantum Disinfection (“QD”) are two of the most widey used methods. Disinfection is typically the final stage of any cannabis water treatment system. UV works by destroying the DNA of the bacteria while QD works by relieving bacteria of electrons which causes the cell to implode and cease to exist.

Total Dissolved Solids

Defender ROTotal dissolved solids, called “TDS” for short, is a measure of the levels of cations and anions in the water. Cations (positively charged ions) are sodium, posassium, calcium, and magnesium, while anions (negatively charged ions) are carbonate, bicarbonate, chloride and sulfate.

Many experts believe that rainwater is the best type of water to using in growing cannabis, however do not believe that rainwater is totally pure. Chemical and bacterial contaminantion is common in rainwater. Rainwater is low is TDS and is usually slightly acidic, often in the 5.6-6.0 range range. Cannabis thrives at a pH around 6.5. Some feel that as low as 6.2 is ideal. Whatever level you choose, you should try and keep it consistent.

SOLUTION: Reverse osmosis (“RO”) usually removes 98-99% of the TDS and leaves the water with a pH of 6.0 to 6.5, but after it sits in a tank it will generally raise to neutral. Reverse osmosis strips out all the minerals (cations and anions) leaving just pure H2O. At that juncture, you must add all the nutrients your plants will need into the water, before giving it to your plants. Mineral-free water will suck the vital minerals away from your plants. This is usually does with chemical injection pumps are by manually adding the minerals to a tank.

Odds are, the water profile you have is not the profile you need to successfully grow cannabis, so the most successful growers start by removing all of the minerals and then building their own water profile bt the addition of the exact amount… consistently, day-in-and-day-out.


Again, some growers feel that a pH of 6.2 to 6.5 is most conducive and others may want higher or lower levels. The fact is: pH is a real thing and must be controlled. Plants seem to thrive after a rain, which is slightly acidic.

SOLUTION: pH can easily be adjusted and monitored with a pH controller (pictured to the right). There are numerous forms of acid that can be added depending upon what water profile you might desire. Frequently, RO water is very close to the profile many growers desire.

InfusionIron, Sulfur, and Manganese

These contaminants, even in small concentrations, are deletrerious to plants… especially the cannabis plant, as they coat the leaves, plug the pores and clog the root system of plants. There is simply nothing beneficial about having iron, sulfur and/or manganese!

SOLUTION: If you have iron and sulfur, it should be oxidized and the most successful method of oxidation is usually hydrogen peroxide. Manganese, on the other hand, is difficult to oxidize and is frequently best removed by ion-exchange. In any event, the water should be free of irin, sulfur and manganese. While this can be difficult to accomplish by conventional means, it is easy to do with broper oxidation.


A system may look like this:

Cannabis System

Be sure and get a detailed water analysis like THIS and rely on someone who is a Certified or Master Water Specialist to recommend a system that will help you grow the best cannabis this side of heaven.


Peace out...


February 4, 2020
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