Medical Cannabis – M A Nichols – November 2017



LINK – MEDICAL CANNABIS Dr Mike Nichols 07.11.2017

Medical Cannabis   – 7 November 2017

  1. M. A. Nichols1

110 Newcastle St, Palmerston North 4410, New Zealand.


The medicinal use of cannabis is not a new, as until the 1930’s cannabis was a regular component in the chemist’s arsenal against pain. At about that time cannabis use was essentially banned in the USA, and eventually throughout the world. Things have now changed, and there has been a general relaxation of the law, particularly in the USA and Canada. Australia and New Zealand are likely to follow the general world-wide trend, but how best to grow the crop for medical purposes has yet to be determined. In this presentation I will provide an introduction to the various types of cannabis, examine some of their different medical properties, suggest how they might be best grown for medical purposes, and consider possible methods by which the cannabinoids are ingested.


Keywords: cannabinoids, thc, cbd, medicinal


There has been considerable interest recently in both Australia and New Zealand regarding the possibility of using cannabis for medicinal purposes. Early in 2015 the Norfolk Island Government approved the growing of medicinal cannabis on the Island, but this decision was rapidly countermanded by the Australian Federal Government in Canberra. It now appears that it is only a question of time before the Federal (and State) Governments in Australia will approve the growing and selling of cannabis for medical purposes. In November 2015 it was announced by the Turnbull government that they will introduce a national scheme to legalise medicinal cannabis by licensing growers, which could pave the way for a local industry. Health Minister Sussan Ley said that the government had drafted legislation to establish a single scheme for growers in all states and territories, which would be introduced in Parliament’s early in the next year. Both the Victoria and NSW State governments have previously indicated they want to legalise medicinal cannabis, and are waiting on a federal regulatory scheme.

The medicinal use of cannabis is not a new use for the plant, as until the1930’s cannabis was a regular component in the chemist’s arsenal against pain. At that time cannabis was banned in the USA, although the true reasons are unclear but suggestions are that:

  • the hemp fibre was too competitive with the new artificial fibres developed by Du Pont
  • The psychoactive drug was resulting in the rape of nice white American girls by Mexican emigrants
  • It was to find employment for the many inspectors who had previously been employed with the alcohol prohibition.

Whatever the reason, it is clear that during the 41-45 war the USDA strongly promoted the growing of cannabis (as hemp) for the fibres as anchor ropes etc, but as soon as the war concluded all the booklets on how to grow the crop were pulped, and the USA (via UN) promulgated the banning of cannabis world-wide for all purposes. A move which New Zealand went along with, and essentially only a few countries particularly those behind the “iron curtain” did not.

So what is cannabis?



Arguments still exist regarding the precise botanical classification of the plant, as to whether it is Cannabis sativa or Cannabis indica (or even Cannabis ruderalis) but for the purpose of this article we will only classify it according to uses. Essentially these are:

Industrial Hemp

A low THC type which is used for fibre (it is the world’s strongest natural fibre) or for the oil produced in it’s seed or as a “mop crop” for absorbing waste water nutrients from sewage plants or freezing works.

Medicinal cannabis

A high THC type which is used for pain relief or a high CBD type which is used for epilepsy (and other nervous) problems.

Recreational cannabis (marijuana)

A high THC type which is used recreationally as a psychoactive drug.

All the above types are generally considered to be either the species Cannabis sativa or Cannabis indica, or a cross between the two species.


My involvement with cannabis started in 2001 when I was invited to become the Research Team Leader for the NZ Hemp Industries Association (NZHIA), and as a result I found myself learning now only about hemp, but also about medicinal and recreational cannabis production, leading to a meeting with the management team of GW Pharmaceuticals in London, and a visit to the Bedrocan medicinal cannabis growing operation in the Netherlands. The only 2 organisations legally growing medicinal cannabis in the world at that time.

Recently there have been major changes, with about half the States in the USA allowing the growing of medicinal cannabis, and some (4 at present) allowing the legal growing and use of cannabis for recreational purposes

It is to be hoped that if we (Australasia) are to develop an export industry with medicinal cannabis, that the necessary research will be undertaken in order to establish the most efficient method to produce a high quality product.

The Australian Scene

No doubt this has been stimulated by the donation of $AU 33.7 million by Joy and Barry Lambert to fund medicinal cannabis research at Sydney University. Clearly in the future Australian medicinal cannabis research will become mainstream with that sort of backing.

The New Zealand scene

In a recent survey there was general agreement that recreational cannabis use should be decriminalised, however the water in relation to medicinal cannabis use was not considered, and government is against any relaxation of the current laws regarding cannabis recreational use.

Research on medical cannabis

In fact there has been very little research worldwide on either the production of medicinal cannabis, or on the medicinal properties of the different cannabis strains.  GW Pharmaceuticals (, are probably the leading company in terms of researching the clinical aspects of cannabis, but they do not appear to have undertaken much in terms of cannabis production research. The other major company (Bedrocan – are really a production company and did not appear to have a research arm. Their production is in a plant factory with lighting provided by fluorescent lights (young plants) and by High Pressure Sodium lights (HPS) for mature plants. The only published research work on the production of non hemp cannabis (ie medicinal/recreational) in a “plant factory” has been by a research group in Belgium who demonstrated that plant density played a role in productivity, and that there were some genetic differences, and that in general terms 1 g of dried cannabis head was produced for every 1 watt of HPS electrical light used. (Vanhove et al., 2011; Vanhove et al., 2012.) The project undertaken by ESR in New Zealand was more in the realm of lets grow some high THC cannabis and collect some data. (Knight et al, 2010).

Apart from these three studies there are not any peer review scientific papers on how best to produce medicinal cannabis, although the web offers a huge amount of information (of uncertain reliability) on the growing of cannabis either for recreational or for medicinal purposes. No doubt the commercial producers of medicinal cannabis in both Canada and USA have research programmes, but these results are likely to remain in-house.

What is cannabis

Essentially cannabis is a complex plant in terms of it’s medicinal properties as it contains both THC (Δ9 tetra hydrocannibinole) and CBD (cannabidiole) along with a large number of other cannabinoids and terpenes, which may also have medicinal properties.

In very simplistic terms the level of THC determines the pain relief properties of the plant, while the CBD level has a major influence on the effect of cannabis on the nervous system. However, it is clear that both have a synergistic effect on the other, along with the effect of the many other cannabinoids. There are strong opinions that cannabis can have valuable effects on a wide range of medical conditions, and there is a real danger of it being considered a panacea for all human ailments. We have a lot to learn.

Dravet’s syndrome (a severe, intractable, and eventually fatal, childhood form of epilepsy) appears to be ameliorated to some extent by the use of high CBD cannabis types, of which the selection of the variety called “Charlotte’s Web” appears to have a strong following. This one plant is believed to be one of the tipping points in the decision to make medicinal cannabis an acceptable medicine in USA, and thus open the door to similar decisions in other countries. In fact, 23 US states now permit the use of medicinal cannabis, and 4 states actually permit its use for recreational purposes.

Professor Lyle Craker of the University of Massachusetts has argued strongly for over 20 years for approval to grow cannabis for medicinal purposes, but has continually been turned down by the US Federal Government. A decision was then made to allow the plant to be grown under local (State) law, with it still being a prohibited plant under Federal law!!! Funny old world. The genie is well and truly out of the bottle.

It is now generally considered that cannabis is a far safer “drug” than alcohol, and that if alcohol was invented now, it would certainly be on the prohibited list!!!  Note: this is NOT a suggestion to legalize recreational cannabis use, or to promote alcohol prohibition simply a known fact.  It is an interesting fact that in New Zealand the producers and purveyors of alcohol may receive knighthoods, while the equivalent cannabis suppliers may receive a prison sentence!

In Canada, where medicinal cannabis is now legal, one producer (Aphria) in Leamington (Ontario) already has 2/5 ha of greenhouses growing high quality medicinal cannabis, and has plans to double this area in the near future. Currently they grow 12 different varieties which range in drug content from 22% THC and 0% CBD to 1.4% THC and 9% CBD. This is sold for about $NZ9.00/g, substantially lower (about half) than the price of illegal high THC cannabis in New Zealand.

Medicinal tests of cannabis

For most (all?) medicinal drugs there is a standard procedure for testing which involves, initially animal tests, followed by human tests. With the objective of determining the sort of response the population will have to different levels of the drug.  These are then followed by blind and later double blind clinical tests in which the patient does not know whether they are receiving the drug or a placebo, or the more robust double blind test in which the doctor does not know also.  This is the procedure used by GW Pharmaceuticals for their research.

I am not aware of any such tests being undertaken in USA, and as GW Pharmaceuticals produce only a single THC based medicine (Sativex) and a high CBD based experimental medicine (Epidiolex) and some (many?) North American medicinal cannabis growers provide a wide spectrum of THC/CBD levels in their product, it is difficult to see the North American situation fitting into the Australasian medicines requirements. It appears to be more similar to that of a herbal medicine.

Delivery of the drug

Aphria have recently received approval to develop a cannabis oil, which will allow the production of capsules containing precise quantities of THC and CBD. In this respect they differ from the UK producers (GW Pharmaceuticals) ( who dispense their medicinal cannabis via a buccal spray, or the Dutch producers (Bedrocan) who use a vaporizer. Generally in North America smoking (as in recreational cannabis) appears to be the norm.  Aphria ( are developing a cannabis oil for oral consumption.

Growing medicinal cannabis

If we are to establish a medical cannabis industry in Australasia we have to establish sound horticultural growing methods to maximise the yield of the desirable chemicals. Growing medicinal cannabis in a greenhouse has significant cost advantages compared with plant factory production, but requires considerable specific skills to ensure freedom from pests and diseases (an important factor in any medicinal product). In addition it is essential to have the sort of knowledge of day length control (such as the year round chrysanthemum growers have), as flower production in cannabis requires short days. This is much easier to achieve in a plant factory, fully lit by artificial lights, but the current knowledge is mainly with using High Pressure Sodium (HPS) lamps, and knowledge on how best to make use of LED lights for cannabis production is still to be fully explored..

For example we know that the drug content is likely to be enhanced by the use of UV B light close to harvest, but it could well be that other specific wavelengths could also have a marked effect on the level of drugs produced in the plant.

Plant factories also have the advantage that (potentially at least) they can be made relatively free from pests and diseases, by ensuring that only filtered air enters the factory, and that there is always a positive pressure inside the room. The use of any pesticides is a not a good idea for any crop to be used for medicinal purposes!!

So what are the basic principles to consider when growing medicinal cannabis?


Growing medicinal cannabis 101

For a start it must be noted that although it is possible to grow medicinal cannabis from seed it is very important to have the right variety, and this means that clonal propagation is essential. This means that it is necessary to grow the plants from cuttings, which must be produced on “mother” plants which are grown under a non-flowering (long day) regime. The second important factor is that the drug content is found predominantly in the un-pollinated female flower heads. Fortunately with very few exceptions cannabis plants are dioecious (it has distinct male and female plants), so if you take cuttings only from selected female plants you will have only un-pollinated flower heads.  The third fact to note is that cannabis is similar to chrysanthemums, in that it remains vegetative under long days, and requires short days in order to flower, and remains vegetative in long days (over 12 hours).

This means that we need to have two distinct sets of plants, namely: –

  • Mother plants, which are grown in long days to ensure that the cuttings they produce are vegetative
  • Cropping plants which start off initially as cuttings and then at some later stage in growth are given short days to ensure that they produce flower heads.

In the field, cannabis will only flower in the autumn, and so we will only obtain a single crop per year. If we grow in a greenhouse it is possible to achieve 3 crops per year, by using artificial lighting to give the required long days (for vegetative growth) during the winter months, and black out curtains to provide short days (for flowering) during the long days in the summer. Thus we can make the plant believe that it is whatever season we wish. This is similar to the production of year round chrysanthemums.

Of course if we grow in a plant factory, entirely under artificial lights, then these conditions can be applied simply by means of a time clock.

The next question is how best to grow the plants, after the cuttings have been produced (and rooted)?  Soil is not a good medium in which to grow plants, and the New Zealand police actually categorize the intensity of an illegal cannabis crop in terms of whether it is soil grown or hydroponic. Growing hydroponically is considered to demonstrate greater skill, higher yield and therefore greater culpability.  Nutrient film technique (NFT) is considered to demonstrate the greatest skills, although personally I suspect that an ebb and flow system using a growing medium might in fact be superior.

There are a very real number of questions that still remain unanswered in relation to medicinal cannabis production, such as:-

  • What is the optimum plant density?
  • How long should the plants be grown vegetatively before initiating flowers?
  • What is the optimum temperature?
  • What is the optimum lighting? Intensity, wavelength
  • And of course is greenhouse production more efficient than using a plant factory.

It should be noted that plant factories for cannabis really only developed in order to hide the operation from the police.

Medicinal cannabis production research

The only published high THC cannabis research carried out in New Zealand was by Knight et al (2010) of the Crown Research Institute of Environmental Science and Research (ESR), who grew 3 crops. Because of their acknowledged lack of horticultural skills they used a previously convicted cannabis grower as a consultant. Only the first crop performed to a reasonable standard, as the second crop succumbed to spider mite, and the final crop also had some problems. The value of her research from a scientific point of view is doubtful, as little (no) information is provided about the growing environment or even in fact the actual plant density being used. All the results are only of the yields per plant. This was at the request of the police.

The two Belgium studies, undertaken at the University of Ghent at the request of the Belgium police is much more forthcoming. They provide us with information on different cultivars and plant densities, and of course the yield of dried heads from the different treatments. Undertaken from a recreational drug view point, the information obtained is likely to be relevant not only for high THC medicinal cannabis production, but also for the production of high CBD medicinal cannabis. All the results to date suggest that the yield of dried cannabis head approximates to 1g for every watt of power used in lighting.

The downside of the Belgium study is that the light source was High Pressure Sodium lamps (HPS), and these are being rapidly supplanted with LED lights, which are cooler, much more efficient and with far long life. With our present state of knowledge LED’s should be used at a 4:1 ratio of red/blue, along with a small amount of “white” light, but this is something that I am sure our North American friends are investigating under the legal production regime that exists in much of North America.

Literature cited

Knight G, Hansen S, Connor M, Poulsen H, McGovern C & Stacet J (2010). “The results of an experimental indoor hydroponic cannabis growing study, using the `Screen of Green’ (ScrOG) method–Yield, tetrahydrocannabinol (THC) and DNA analysis”, Forensic Science International, 202(1-3), 36-44

Vanhove, W, Van Damme P, & Meert, N. (2011) “Factors determining yield and quality of illicit indoor cannabis (Cannabis spp.) production” Forensic Science International, 212 (1-3), 158–163

Vanhove, W, Surmont. T, Van Damme P, & De Ruyver, B.  (2012) “Yield and turnover of illicit indoor cannabis (Cannabis spp.) plantations in Belgium”. Forensic Science International. 220 (1-3), 265–270



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