Sterilization in the Cannabis Industry

Sterilization in the Cannabis Industry

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Written by: Dan Butler

Public perception of cannabis has dramatically changed over the past decade, with two-thirds of Americans now in favor of legalization, and an entire industry has sprung up around. In fact, Grandview Research valued the global legal cannabis market at $13.2 billion USD in 2021, with a projected compound annual growth rate of 25.5% from 2022 to 2030.

As the demand for safe, legal cannabis products increases, growers face new challenges, including adopting new cultivation methods, navigating a constantly changing regulatory landscape, and ensuring quality control at every stage of the growth cycle. Proper steam sterilization is integral to all of this.

In this article, we’ll explore the role sterilization plays in cannabis tissue culture cultivation, and why an autoclave is an essential piece of equipment in any grow facility.

Table of Contents

What Is Micropropagation?

In years past, producers of medical and recreational cannabis relied on a method of reproduction and propagation known as hydroponic cloning, or simply cloning. With cloning, growers cut a piece off of a living marijuana plant — known as the “mother plant” — place it into a growing medium, and give it a hormone to encourage growth. Once the new plant, or “clone” — which has the same genetic makeup as the mother plant — grows roots, it’s transplanted into a pot or the ground, where it proceeds to take root and grow.

Although cloning is an effective propagation method, it does present certain challenges:

  • Yields are ultimately limited by spatial constraints.
  • Pests, pathogens, bacteria, fungi, and other harmful microorganisms can pass from the mother plant to the clone.
  • Although mother plant specimens are selected for their desired genetic traits, there’s no guarantee that all clones of that mother plant will have those same traits.

That brings us to tissue culture propagation, also known as micropropagation.

The American Phytopathological Society explains that micropropagation:

“[…] involves the use of small pieces of plant tissue (explants) which are cultured in a nutrient medium under sterile conditions. Using the appropriate growing conditions for each explant type, plants can be induced to rapidly produce new shoots, and, with the addition of suitable hormones, new roots. These plantlets can also be divided, usually at the shoot stage, to produce large numbers of new plantlets. The new plantlets can then be placed in soil and grown in the normal manner.”

According to the Cannabis Industry Journal, this approach to cannabis cultivation is gaining traction due to its ability to:

  • Take up less space than hydroponic cloning propagation
  • Isolate viable plant tissue in a controlled, sterilized environment
  • Allow for the standardization of quality strains free of contamination and disease
  • Prepare plantlets for indefinite storage, allowing for the creation of Maitri genetic libraries for future cultivation
  • Preserve plant genetics, particularly for in-demand and heirloom strains

Additionally, micropropagation enables growers to engineer better strains of cannabis, supports the rapid dissemination of new strains, and allows for mass production at a limited cost. These benefits make micropropagation better suited for the mass, commercial production of marijuana plants for medicinal and recreational purposes than the hydroponic cloning method.

The Role of Steam Sterilization in Tissue Culture Cultivation

In order to use the micropropagation method for cannabis cultivation, growers must first have an aseptic environment in which they can isolate viable plant tissue and grow new plantlets. This requires the setup of a cannabis testing lab, including sterilization equipment.

Though growers have a few options available to them, using an autoclave for steam sterilization is by far the most efficient and effective way to achieve sterility, and can be used on:

  • Lab equipment
  • Glassware
  • Growth media, including soil/compost, Rockwool, hydroponics, coco/perlite, and vermiculite

Check It Out: The Beginner’s Guide to Autoclaving Soil >>

How to Use an Autoclave for Micropropagation

The process for using steam sterilization for tissue culture cultivation is fairly straightforward:

  1. Select a mother plant based on desired genetic traits, including physical characteristics, terpene profile, chemotypes, and phenotypes.
  2. Prep glassware culture vessels for sterilization.
  3. Prep growth media, which should consist of a variety of nutrients, vitamins, and hormones; agar, a solidifying agent, is often added as well.
  4. Sterilize glassware and media using an autoclave. If sterilizing glassware and growth media at the same time, use a liquids cycle to prevent boil-over. If sterilizing glassware alone, use a gravity cycle.
  5. Store autoclaved glassware and growth media in a sterile environment.
  6. Find the healthiest part of the mother plant at the apical meristem and make precise cuts to remove it from the plant. The apical meristem is the ideal place to make cuts because it is actively dividing cells and forming new tissue. Precision is essential here; although small cuts are best for removing potential viruses, diseases, and fungi, they make it difficult for the plantlet to root.
  7. Sterilize the cannabis plant clipping using chemicals similar to isopropyl; this is known as the inoculation phase.
  8. Place the plantlet in the growth media inside the glassware with the cut piece facing downward. This is known as the incubation phase.
  9. The plant will then grow roots after several weeks during what’s known as the rooting phase. Once the roots have grown, it’s possible to further culture the clipping to multiply the plant, at which point the entire process is repeated.
  10. Once the roots have grown, transplant the plantlet into a soil pot.
  11. Acclimate the cannabis plant in a controlled, moist environment. This is incredibly important because the environment inside the culture vessel is near 100% humidity, and transferring the plantlet from an environment that is 100% humidity to one that is 50% humidity can be very damaging.

How CSS Supports the Legal Cannabis Industry

Consolidated Sterilizer Systems provides autoclaving equipment to some of the largest commercial growers in the United States and Canada. The most common models are the SSR-3A and SR- 26A:  20x20x38”  and 26x26x39” chambers, respectively.  These units are typically supplied with on-board, integral, steam boilers (because house steam is not available.)  The sterilizers are provided with turnkey-installation where an authorized CSS installation team will set the unit in place, make final connections, start it up, and provide end-user training – all of which happens in about 1 – 2 days, depending on location of utilities. After all of this takes place, the Cannabis facility is off and running.

To learn more about our autoclaves and how we can support your growing facility, contact us today to schedule a free consultation.

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