The importance of magnesium in the production of CBD rich hemp

What is magnesium?

There are three groups of plant nutrients: primary, secondary and micro. The three primary nutrients are the ones represented by the numbers on the front of all fertilizer containers:  N-P-K, Nitrogen-Phosphorous-Potassium. The three secondary nutrients are Calcium, Magnesium and Sulfur. Their symbols are Ca, Mg, S. There are eleven micronutrients to be concerned with when growing, and we will not be discussing those  in this post.


Most farmers and gardeners focus only on the primary nutrients, NPK. However the secondary nutrients are just as important and either too much or too little of one of them can seriously decrease your yields.  In fact, there is a school of thought championed by Albrecht, Kinsey and others that the ratio of Ca:Mg:K is more important to pkant/soil health and yields than NPK. This known as the Basic Soil Cation Ratio.  The subject and focus of this blog post is the secondary nutrient Magnesium.


Plant leaves are nature’s solar cells. Through the process of photosynthesis, green plants use solar energy to convert water and carbon dioxide into carbohydrates and then release oxygen as a waste product. The green pigment in the leaves that  allows photosynthesis to take place is called chlorophyll. AT the very center of each chlorophyll molecules sits one magnesium atom encased in what is known as a chlorin ring.  Four nitrogen atoms in the chlorin ring surround and bind the magnesium atom. Nitrogen is well known for the nutrient that promotes deep green leafy growth, and now we understand why…because 4 nitrogen atoms are in the chlorophyll molecule binding to the sole magnesium atom. This arrangement also tells us something about magnesium. Magnesium is also essential to get than deep green leaf color. Without magnesium, chlorophyll does not exist. Without chlorophyll, most life on earth does not exist.


You would think magnesium’s presence being require for chlorophyll would be enough, but magnesium is a classic over-achiever. Magnesium also acts as a phosphorous (the “P” in NPK) carrier in plants. Without magnesium phosphorous uptake could not occur. This is very important information for cannabis growers as phosphorous demands in cannabis increases as it passes from the vegetative stage to the bloom stage. This is the reason bloom fertilizers have a higher amount of phosphorous. If your plants lack sufficient magnesium to make use of that expensive phosphorous then your yields are lower and you have wasted money.  But wait, there’s more! Magnesium is also essential  for plant respiration and the activation of several enzyme systems. What a workhorse for a secondary nutrient.

How do you identify a magnesium deficiency?

Magnesium is one of the nutrients that is mobile in a plant. That means that when a deficiency occurs the plant is able to move magnesium from older growth to support new growth. So a magnesium deficiency will first show in the older leaves. Visually it appears as interveinal chlorosis…the loss of color between the leaf veins, beginning at the leaf tips and margins and working its way to the center. So the edges and tips of the leaves will yellow and the veins and center of the leaves will be green. When you see this you want to take quick action to correct the deficiency, especially if your plants have already entered the bloom phase.

magnesium deficiency in cannabis
This cannabis plant has a severe magnesium deficiency caused by use of a high potassium bloom fertilizer
closeup of magnesium deficiency in cannabis
In this closeup you can clearly see the interveinal chlorosis. Note the yellow margins and green veins and center of the leaves.

The two photos to the left show a cannabis plant 8 days after the first symptoms of a rather serious magnesium deficiency showed itself. The classic yellow margins and tips with green veins and venters of the leaves. You can see the flower buds at the tips of the stems so this plant is at a  very critical stage in its development and this magnesium deficiency needs immediate attention.

How to correct a magnesium deficiency:

The quickest, easiest and most cost effective way to correct a magnesium deficiency is with magnesium sulfate…Epsom Salts. I live in a rural farming area so I can just go to an agronomy center and purchase a 50lb bag of solution grade Epsom Salts for under $25.  That 50lb bag will last me several years and will be used on CBD rich hemp as well as the solanum family: tomatoes, peppers, eggplant and tomatillos.

You can apply magnesium sulfate in several ways. 1) sidedress, scatter a small handful of Epsom Salts right on the soil surface around the outside of the effected plant.  2) add it to your nutrient solution at a rate of 1 pound/100 gallons of water. 3) as a foliar spray, which is the quickest acting method.  This plant is well into the bloom stage though so we don’t want to use a foliar spray that might leave a residue that will give a harsh or off flavor to the final product. So in this case we used the sidedress method and scattered a small handful of Epsom Salts on the soil surface and watered it in well…until now granules were visible on the surface.

Sidedressing and watering it in was still very quick acting. The plant was noticeably greener in 3 days. Within 6 days the plant was looking very healthy and growing again.

magnesium deficiency cured using epsom salts
This photo is of the same plant take 6 days after being treated with Epsom Salts. Green, healthy and growing again

This plant was one of a planting of 52 cannabis plants in a licensed, legal medical marijuana grow. About 12/52 plants developed symptoms of the magnesium deficiency when the grower changed over to his “bloom nutes”. We went ahead and gave every plant the same treatment. After seeing the results in 5 days, the grower went ahead and gave all of the plants a second treatment at 14 days.

When you make your fertility plan for a grow whether it is cannabis, or any other crop, be sure to include magnesium. I this case, it was the grower’s first outside grow. He had been growing for years indoors and had been taught that he only needed to concern himself with calcium and magnesium when using a coir based growing medium.

This case study illustrates the importance of having soil tests done well before you plant the first seed. Get the full soil test with NPK, secondaries and micronutrients. Also %organic matter, base cation ratios and cation exchange capacity. The cost isn’t that much more and the possible increase of yields by making your fertility decisions based on more complete data will pay for the tests many times over.


If you need to buy some CBD please click on the “ONLINE STORE” button on the menu at the top of the page and buy a bottle of Della’s Garden High Potency, full spectrum CBD oil. It’s vegan, it’s organic, gmo and gluten free. Owned and grown by a US Navy veteran. Be sure to use the coupon code JORGE35 at checkout to get $35 off the price of each bottle.  Shipping is always free within the USA.



THC in hemp…time to dispel a huge myth.

All hemp is cannabis. Not all cannabis is hemp. What is the difference? You can’t tell by looking or smelling. You can tell by smoking…if you get high then it isn’t hemp. There is where the difference lies…hemp, by definition has less than 0.3% THC. There is no limit on the other cannabinoids, in fact we want them sky high!

The difference between marijuana and hemp then is not a natural one, but a legal definition assigned by the government. In the United States hemp must have a total THC of under 0.3%. ” Total THC” means “the molar sum of delta-9 THC and THCA [tetrahydrocannabinolic acid].”  In the European Union the number is 0.2%.  In practice, at least in Oregon where we grow hemp, you are allowed up 0.35% total THC to allow for testing errors.

So here is a picture of cannabis that I really hope tests as hemp when flowering begins.

You see, it is not actually hemp until it has gone through a Compliance Test by a 3rd party laboratory.  The grower submits a written request for a compliance test to an accredited laboratory. The lab sends a technician out at the appointed time who fills out a “Chain of Custody” document with the grower and then proceeds to sample the field.  When the lab finishes its test, the results are emailed to the Oregon Department of Agriculture. At the moment the ODA signs off on the compliance test, the cannabis in the field magically transforms into hemp.

For compliance sampling to proceed the field must be in the early flowering stage like this:

After the compliance testing is completed, in 2020 we have 28 days to complete the harvest. If we don’t meet the 28 day window for harvest, we must compliance test again.

Next year the harvest window is going to be cut in half to 14 days. This is a very big deal because you want to test early enough that there is a very low probability of “going hot”. “Going hot” means having a THC level that exceeds the total legal limit. That is the worst thing that can happen to a hemp grower. If your compliance test comes back above the legal limit your crop must be destroyed. Starting next year, a hot compliance test must be forwarded to the federal Drug Enforcement Agency…so really a grower needs to not go hot.

So this is where “The Myth” I referred to in the title comes into play. Because cannabis has been illegal for decades and listed as a schedule 1 narcotic, very little research has been done into how cannabis grows. People were putting out their best guesses as to how and why a hemp plant goes hot. While the intentions were good, the guesses based on almost no data turned out to be bad.

The guess that seemed to be most plausible and gained traction was that “CBD develops first and then after CBD peaks THC starts to rise.” Several scientists, including my friend Clint Shock put that myth to rest last year

What really happens is that the genetics of the plant determines a set ratio of CBD:THC, and both CBD and THC develop at the same time. In fact, Dr Shock has made the case to the USDA that the definition of hemp needs to be changed from 0.3% or less THC to cannabis having a minimum of a 20:1 CBD:THC ratio. In other words if you have 20% CBD you will have 1% THC. 1% THC isn’t going to get you high, especially with 20% CBD which interacts with THC in the body to reduce the psychoactive effects of THC.

Clint’s research at his facility in Ontario, Oregon last year which he released on  November 22, 2019 in a report titled: “Hemp and its regulation: the small background of THC in CBD hemp” At this point I am just going to copy and paste from Clint’s document so I do not change his meaning:

He starts by describing how the new USDA Draft rules will cripple the nascent hemp CBD industry and offers this solution:  “The potentially detrimental USDA policies can easily be averted by the
following: 1. For hemp flowers with greater than 6% CBD, edit the 0.30 % total THC rule to permit hemp flowers grown for CBD that have a ratio of 20:1 or more of total CBD to total THC, regardless of the THC content. 2. Allow growers six weeks to harvest their crops after approved sampling for potency.”

Here is the abstract of his research:

In 2019 we grew thousands of genetically different CBD hemp (Cannabis sativa) plants as part of our breeding and selection program to create and identify lines of hemp beneficial for
growers. Plants were grown in Ontario, Oregon. Between September 23 and 29 we sampled flowers from 273 unique hemp plants. All the germplasm tested had been designed to provide CBD. The 273 samples were submitted to laboratory analysis along with 5 check samples from the same field with known cannabinoid content. The 278 samples were analyzed for cannabinoids by Integrity Labs, LLC, 2747 Pacific Ave SE B21, Olympia, WA 98501 (WA State
I502 Certification #09). The results were used to evaluate the amounts of CBD, THC, and other cannabinoids that can be expected in CBD hemp. Repeated weekly flower samples were taken
from 28 clones, submitted to Integrity Labs, and data from one clone is presented to show the trends over time of total CBD, total THC, and the ratio of total CBD to total THC.

I have heavily edited Clint’s results to just the parts that dispel the myth of ‘CBD develops and peaks 1st, then THC starts to develop. The emphasis was added by me.

No Delta 9 THC was detected in any of the 278 flower samples (Figure 1). A low background of THC was detected in all of the flower samples. The background THC concentration increased with the CBD concentration. The ratios of total CBD to total THC ranged from 22.4:1 to 32.1:1 among this set of germplasm The ratio of total CBD to total THC was not enhanced by early harvests. Due to the relative stability of the ratio of total CBD to total THC over time, there is no point in restricting growers to a narrow harvest interval following potency testing.

My data from last years crop lines up nicely with Clint’s:

9/23/19     THC=ND    CBD = 1.82%…compliance test

10/04/19   THC=0.15  CBD = 4.49…preharvest potency test of buds

10/23/19   THC=0.34%   CBD = 9.88%..preharvest potency test

11/25/19   THC=0.49%  CBD = 13.18%  post harvest flower buds

11/25/19   THC=0.23%  CBD = 6.8%  post harvest biomass (all buds + leaf)

02/27/20  THC=2.52%  CBD = 59.8% filtered and decarbed crude after extraction

You can see from my test data that THC developed at the same time as CBD and the ratios stayed in a tight range of 27:1 – 30:1, that carried through to the extracted crude oil as well.

So the data clearly shows that THC and CBD develop concurrently, not separately. Additionally, the data shows that the CBD:THC ratio is set by genetics and varies little over the lifespan of the plant. Unfortunately some writers have published the myth of CBD 1st then THC later. Even presented with the science on multiple occasions they refuse to update their knowledge to match the current science.

All hemp is low THC, both by definition and by genetics. By politics and by science. Breeders are pushing hard to increase the ratio which is typically in the range of 25:1 to 40:1. Some breeders are claiming 50:1 or higher, but I am skeptical until I see independent data.

The new darling of the industry is CBG rich cannabis. CBG plants have an even higher ratio than CBD plants…80:1 CBG:THC and higher. This higher ratio makes it easier for the grower to stay legal while still producing enough CBG to profitably extract.


Regenerative Farming

Regenerative farming is a marketing term that was coined in the 1980s by Robert Rodale of the Rodale Institute and publisher of Organic Gardening and New Farm magazines. He felt that the term “sustainable” was a poor choice because it felt like just trying to maintain where we are now without striving for improvement.

Robert Rodale defined Regenerative Agriculture as follows: “the term “regenerative organic” to describe a holistic approach to farming that encourages continuous innovation and improvement of environmental, social, and economic measures.” For him, the continuous innovation and improvement was key.

Regenerative farming and Organic farming were both the standard way of farming before the advent of chemical fertilizers and pesticides…what is now called “conventional agriculture” Before the chemical revolution, regenerative and organic were just called FARMING. For example, my mom Della, grew up on a 100 acre farm outside of Nampa, Id which incorporated many of the components of regenerative ag. First, there was a mix of crops and livestock and poultry. Up to 10 different crops were rotated through the fields with the livestock. The manure was all returned to the fields to build soil health, fertility, and that elusive quality we refer to as “tilth”

On my little 20 acres in the Willamette Valley I rely pastured pigs and geese to turn and fertilize the soil. There is no money to be made on pigs, but they add so much to the health of the soil, and that is always number one consideration for me. They graze, they turn the soil over, they root up weeds and in time leave a pasture comprised of the vegetation they find most palatable. I have beautiful pastures of mixed clovers and ryegrass that I did not plant…the pigs cultivated them to suit their palates.

A key thing about pigs is that they are not ruminants like a cow or sheep. Their digestive system is much closer to a humans, with a single relatively small stomach. While they love to graze greenery and munch roots and leaves they need to be fed a concentrated ration everyday. As those pigs work through their pasture they spread the feed I provide across the fields in their manure. Pigs have a plow on the front and a manure spreader on the rear. When I take a pasture from pigs and make it a field for growing veggies, or hemp, the soil is incredible!

Here are 2 photos of one such pasture being disced up to ready it for planting vegetable seed…just the 1st pass with the disc and it is beautiful, crumbly and well aggregated. Outstanding looking Willamette Valley silt loam, after 14 years of organic management.

As you can see in the above photos, I always let some weeds grow. The tall ones a Queen Anne’s Lace, which is a wild carrot. Carrots are “umbelliferous”. A botanical term meaning: belonging to the Umbelliferae, a family of herbaceous plants and shrubs, typically having hollow stems, divided or compound leaves, and flowers in umbels: includes fennel, dill, parsley, carrot, celery, and parsnip. Umbels are the preferred nectar source for many beneficial insects…ladybugs, lacewings, tiny parasitic wasps. They need the sugar from the nectar for energy so they can chase down and devour their protein source, the bad bugs that damage crops.

Also, being a little sloppy on the landscape gives habitat to beneficial insects, many different species of birds, amphiibians, snakes, pollinators. I let them use the ground until I am ready to use it for a crop. It is a symbiotic relationship.

Just a quick taste of the vast subject of regenerative farming, and in future posts I will go deeper. I will also relate it to how it ties into producing high quality CBD rich hemp for our Della’s Garden high potency CBD products.

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