Increasing interest in CBD-rich cannabis driven by preliminary research suggesting its efficacy and mounting anecdotal evidence has led patients to seek cannabis with known ratios of CBD to THC with the highest possible total CBD levels.

Driving the search have been patients whose serious medical problems —Parkinson’s, ALS, Autism, Epilepsy, Cancer, MS, various inflammatory conditions, and others— have not been amenable to conventional treatments.

Through our work at Pure Analytics Lab, we have developed a body of information illustrating phenotypic and thus genotypic relationships and distributions of the various desired CBD:THC ratios across multiple generations of CBD-rich varieties.  Of special interest to patients are strains with CBD:THC ratios of 1:1, 2:1, and 20:1.  These observations can hopefully aid the progression of the development of even more Ultra High-CBD cannabis, UH-CBD.

Through 2011, all known commercially available CBD-rich cannabis seed —Cannatonic, Sour Tsunami, et al—produced CBD-rich seedlings at a rate of 25%.  Meaning 3 out of 4 seeds produced THC-dominant seedlings.  As of 2012, some commercially available seeds have been demonstrated to produce CBD-rich plants at a rate of 50%.  These include the Harle-Tsu and Canna-Tsu from Southern Humboldt Seed Collective.

In 2010 the breeding of 2:1 CBD:THC plants with a THC-dominant parent resulted in a few seed populations with a  reliable occurrence of 25% CBD-rich seeds.  Among the CBD-dominant seedlings, a mix of both 2:1 and 1:1 CBD:THC ratios were consistently observed in multiple varieties.  These ratios were first identified in the seedlings and then confirmed through repeat analysis of the final flowers.  In 2011 came reports —validated by lab tests— of plants containing twenty times more CBD than THC.   The unique find was termed “ACDC” by those who possessed isolated female plants. This ACDC strain, also known as C-6, consistently exhibited 16-20% CBD and 0.5-1% THC by weight.  This “ACDC” cultivar was later identified as a variant of Cannatonic, a strain distributed by Resin Seed Co. of Spain then in its second generation of breeding development.

CBD:THC ratios are apparent through lab testing within two weeks of emergence of the seedling from the surface of the soil. 

In 2012, through our vegetative stage testing program, Pure Analytics recorded the distribution of cannabinoid ratios from the cross of 2:1 CBD:THC parents. Seedlings grown from seed stock with a 25% frequency of CBD-dominant phenotypes from different varietals were germinated by independent breeding groups and grown to adequate size for sampling and testing to verify CBD:THC ratios during the vegetative stage.

Seedlings containing 2:1 CBD:THC in the highest levels were isolated from other plants by the growers and allowed to mature until adult flowers were present for breeding and thus seed development. Pollen from 2:1 CBD:THC males was used to pollinate 2:1 females.

Approximately 25% of the resulting seeds (n=40) developed a cannabinoid ratio nearing 20:1 CBD:THC.  ~25% were observed to be THC-dominant; the remaining ~50% were observed to have a cannabinoid ratio of 2:1 CBD:THC.  None of the seedlings in this most recent test population were found to have a cannabinoid ratio of 1:1 CBD:THC.

All vegetative stage identifications were followed with confirmation analysis of the final flowering product from the plant to verify cannabinoid ratios. All results comparing vegetative and flowering cannabinoid ratios were consistent.

Growers can take a strategic, directed approach predicting and isolating desired ratios.

The basic observations of the frequency of THC versus CBD phenotypes in the various generations of the seed populations examined are consistent with the basic genetic model for THC and CBD as it is currently understood with the 20:1 CBD:THC plant representative of the double-recessive condition.  It has now been demonstrated in multiple varieties that this pattern of the distribution of phenotypes occurs with regularity.  Understanding the resulting ratios and potential cannabinoid levels from the various generations of in-breeding can assist the skilled grower/breeder in rapidly developing and isolating the desired ratios within them in a more effective and rapid manner.

The increased availability of cannabis varieties with varying ratios of CBD:THC and ultra-rich in CBD gives a measure of hope to many patients seeking a therapeutic alternative for chronic and difficult to treat conditions.

If you’re interested in learning more about rapid high CBD-strain isolation or other cannabis-related laboratory services provided by Pure Analytics, please visit the company website: or blog: For contact, please Email: 


2 Responses to The Spread of Ultra High-CBD Cannabis

  1. […] The Spread of Ultra High-CBD Cannabis […]

  2. jeffrey p. says:

    CBD rich strains tend to be sensitive. I have had excellent success with T5’s for veg and outdoors for finishing. ACDC produces a beautiful bluish soft flower with a taste and smell rivaling some of the spicy skunks out there. The immediate body reaction to CBD is amazing!!! Swelling. Aches. Tension all alleviated with the use of CBD.

Leave a Reply

Your email address will not be published. Required fields are marked *

Connect with Facebook