Dynamic Accumulators - Nettle Nutrient Analysis


The Cannabis Horticultural Association (CHA) has embarked on a mission to re-analyze the potential of dynamic accumulators. Dynamic accumulators is a term used in the permaculture and organic farming literature to indicate plants that gather certain minerals or nutrients from the soil and store them in a more bioavailable form and in high concentration in their tissues, then used as fertilizer or just to improve the mulch layer. The first to use the term dynamic accumulator in the above definition was probably Robert Kourik in his book Designing and Maintaining Your Edible Landscape—Naturally (1986).

There are people claim there is no scientific data supporting it, and the definition itself varies quite depending on the author. The closest thing with a proven scientific base is Dr. Duke's Phytochemical and Ethnobotanical Databases that is compiled on a USDA website.

CHA is in the process of testing a variety of plants considered dynamic accumulators and then comparing our data with Dr. Duke's Phytochemical and Ethnobotanical Databases. So far CHA has tests results for Nettle, Yarrow and Comfrey. This blog post will cover the results of Nettle and show that there are some very interesting correlations between the two datasets. In this authors opinion, these results provide decent analytical proof that different types of plants do accumulate higher levels of specific nutrients.


If you appreciate our work here, please consider joining CHA. All these analytical tests are funded by our members, and your support can help us continue the research to bring ecological methodologies to the world.


Ecological Concerns Build Over Rockwool Manufacturing and Health


For many decades now, Rockwool has been the cornerstone of the clone and hydroponic industry. Providing a sterile media with excellent oxygen retention, even while fully saturated, rockwool has always been a go to for many. But in light of the changing industry dynamics and ecological calamity of corporate pollution, it is now important to look closer at its manufacturing processes and waste stream and make hard decisions about changing our ways.

Environmental Hazards

As growers and farmers, trying to utilize capitalism while keeping the ecology in mind can be a daunting task. It can be a whirlwind of conflicting views and it’s important to understand how the companies we support impact our environment. Right now there is a big storm brewing over West Virginia and it’s highlighting the environmental problems. The Danish insulation company Rockwool announced its plan to construct a factory that is permitted to release a total of 310,291,620 pounds of regulated air pollutants annually in Jefferson County, WV and Loudoun County, VA. (FORBES). And what are some of the pollutants being emitted into the environment?

CO - Carbon Monoxide. Plays a role in ground-level ozone creation.

NOx - Nitrogen Oxide. Reacts with VOCs to form photochemical smog. Significant amount ends up polluting waterways.

PM 2.5 - Inhalable Fine Particulate Matter. Extremely dangerous, causes cancer, heart and lung problems, and premature death.

PM 10 - Inhalable Coarse Particulate Matter. Larger than PM 2.5, not quite as hazarous, but effects still ranging from respiratory irritation to cancer.

SO2 - Sulfur Dioxide. Associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death. Acid rain precursor.

VOCs - Volatile Organic Compounds. Reactive carbon compounds that are precursors of photochemical smog. Rockwool is permitted to emit 6 VOCs that are known or suspected to cause cancer, including Formaldehyde, which is also a neurotoxin that damages memory, learning, behavior, and physical dexterity.

H2SO4 - Sulfuric Acid Mist. "Occupational exposure to strong inorganic acid mists containing sulfuric acid is associated with increased risks of laryngeal and lung cancer." - U.S. NIH

Lead - Heavy metal neurotoxin. While Rockwool's airborne lead emissions are small compared to other pollutants, no amount of exposure is safe for children and this must be fully vetted.

CO2e - Carbon Dioxide Equivalent. Not harmful.

HAPs - Hazardous Air Pollutants. WVDEP Fact Sheet/Preliminary Findings

Health Hazards

The main health issue for working with rockwool is that it may pose an inhalation hazard when dry. When it is wet, there is no inhalation hazard. The EPA has this to report: “Most studies in humans have not shown an increase in cancer from exposure to glasswool, glass filaments, rockwool, and slagwool. Animal studies have reported an increase in lung tumors in animals exposed to ceramic fibers by inhalation, while no increase in tumors was reported from exposure to glasswool, rockwool, or slagwool. The EPA has classified refractory ceramic fibers as probable human carcinogens. The International Agency for Research on Cancer (IARC) has determined glass filaments, glass wool, rock wool, and slag wool to not be classifiable as to their carcinogenicity to humans (Group 3).” EPA

HOWEVER, research from the Mesothelioma Justice Network has found other past research has linked several diseases with the inhalation or ingestion of some forms of mineral wool. Based on this research, mineral wool health risks include:

“The effects of the fibers of glass wool and stone wool can be compared to those of asbestos. In the past, we did not know asbestos was very dangerous. The results of the effects of fibers in glass wool and mineral wool are only being seen right now, so we must deal with it carefully,” said Dr. Marjolein Drent, professor of interstitial lung diseases at Maastricht University.

How To Protect Yourself From Mineral Wool

The National Institute for Occupational Safety & Health (NIOSH) treats mineral wool like a hazard and still maintains the recommendations that were put into place in 2000 before mineral wool was determined “safe.”

According to NIOSH, workers should protect themselves by wearing:

  • Breathing protection

  • Eye protection

  • Safety gloves

  • Protective clothing

NIOSH also tells workers not to eat, drink, or smoke anywhere near a work site with mineral wool, and to prevent dust from dispersing. Just remember, ROCKWOOL POSES INHALATION HAZARDS WHEN DRY


While the Cannabis Horticultural Association (CHA) has never promoted the use of rockwool for horticultural purposes, it does recognize its widespread use and would like to at least draw awareness to the fact there are methods of composting rockwool. The next section covers 2 methods of composting and 1 trial result provided by a industry representative to provide a framework of understanding how to recycle rockwool via composting. ***The biggest concern we have with rockwool, is that it poses a VERY DANGEROUS INHALATION HAZARD WHEN DRY. It is important for anyone wishing to engage in these practices to understand this. It is of grave concern that farming practices that till the soil with composted rockwool might be exposing themselves to potential inhalation hazards.

1. Generator (Grower) Preparation

• Spent rockwool must be free of all potential contaminants including plastics (no clips, no

twine, no plastic sleeves), trash, etc.

• If spent rockwool has excessive moisture, it should be allowed to dry out for a few days

(dependent on climate conditions and weather). However, excessive dryness is not

desired since the rockwool will eventually turn into a dust or powder which can

become airborne. Ideal condition is "not too wet, not too dry".

• If the grower has a tub grinder or even a wood chipper, the spent rockwool can be

ground up (size reduced) with other green waste and organic materials. This is not

required of the grower but will help in reducing the volume and weight of the material.

2. Green Waste Processor (Composter)

• Spent rockwool can be sized to a 1/4 minus screen using your existing compost

grinders, augers etc.

• Composters should incorporate 10% rockwool to 90% green waste ratio by weight. The

product breaks apart quite easily, and at 10% mixture, the rockwool will not be visible.

• By adding additional granulate (up to 25%), it can also lighten the bulk density of the

compost product depending on the level of compaction. In general, large particles (>1

cm) will ventilate the compost while finer particles (<1 cm) may increase the water

retention capacity.

3. Results from Composting Trials Using Spent Rockwool

• End of life Grodan rockwool, along with vegetation, including roots is an acceptable

feedstock for windrow composting at the 10% rate.

• The compost from the Grodan windrow was indistinguishable from other compost

produced at this facility.

• This feedstock met our quality standards and would fall under the definition of

Agricultural Materials in Title 14(California).

• Process: Windrow composting. Equipment Used: Vermeer TG7000 tub grinder and

Doppstadt 720 trommel screen

b. University of California, Riverside, Department of Environmental Sciences, Contact: Dr.

David Crohn, E-mail:

• The addition of rockwool to green waste during the composting process did not have

any negative impacts.

• In all cases, the addition of rockwool had no significant effect on either germination or

plant growth.

• Used rockwool can be safely mixed with green waste feedstock at low volumes and can

be composted.

• Process: Open windrow. Equipment used: medium sized commercial tub grinder

(Morbark Model 1100) and further screened to 3/4" fines


CHA would like for people to comment on this article and share how they feel regarding these practices. Only when we come together as a community, can we decide how to impact large industries disrupting the ecosystems and our health. Based on the current breadth of knowledge regarding rockwool, it is advisable to begin seeking alternative solutions, like coco base hydroponic media and the bark based cloning media or soil based cloning techniques. We will begin to cover these topics more in depth as time goes on, like the sustainability of peat and the binding agents in the other plugs, but for now, hopefully a few eyebrows have been raised as the butterfly continues to flap its wings…

Want to try something other than rockwool? Give these Root Riot or iHort plugs a test drive….

Companion Planting for Cannabis

Companion Planting for Cannabis

Companion Planting for Cannabis - Examining the Management of Ecological Habitats for Beneficial Insects

Product Spotlight - Baseline

If there is one liquid ingredient worth having around, it’s baseline. Baseline is:

A soluble liquid supplement that feeds beneficial microorganisms; an excellent source of humic and fulvic acids.

It can be used in conjunction with an existing organic or synthetic liquid fertilizer program. It:

•Increases nutrient cycling

•Is an excellent ingredient in compost tea

•Can be used as a stand-alone foliar spray or root drench

•Can be used in drip irrigation systems without clogging emitters

While more expensive than other powdered humics, baseline has many benefits. First off, it is of the highest quality humus and will not create nutrient deficiencies, lockouts or other irregularities sometimes observed with powdered humics. Additionally, its liquid nature makes for rapid tank mixing, unlike other humic powders that get caked onto tank sidewalls and congeal into black clay like dots all over your equipment.

Baseline is basically like plasma for your plants and is a key component to the health of mother plants or any plants that spend many months root bound in containers. Root bound plants can be continuously regenerated by weekly applications of baseline and other microbial products.

Here is a short vimeo video demonstrating the use of baseline in a small nursery in Humboldt County:


Dynamic Accumulators Overview

Dynamic Accumulators planted nearby also function as companion plants, attracting beneficial insects and building soil biology through chop and drop layering and moisture retention through shading on hot summer days.

Dynamic Accumulators planted nearby also function as companion plants, attracting beneficial insects and building soil biology through chop and drop layering and moisture retention through shading on hot summer days.

Dynamic accumulators (DA) are plants that gather certain minerals and nutrients from the soil and store them in higher concentration in their leaf tissues. The leaves of the plants can then be used as compost, mulch or liquid fertilizer.  The truth is that most plants, in a way, are dynamic accumulators in some way because they translocate the soil minerals into their leaves. The difference however, is that certain plants, like horsetail, nettle or buckwheat, for example, tend to pull specific nutrients up in greater amounts.  Horsetail is well known for silica, nettle is well known for iron and buckwheat is known for accumulating phosphorus. Other DA”s like comfrey or yarrow are more all purpose accumulators and pull out more proportional balanced NPK ratios.  DA’s are traditionally thought of as a class of plants associated with nutritive and medicinal herbs. But please don’t confuse DA’s as a specific class of plants, for they can also include other types of flowers and cover crops as well.


Dynamic accumulators (DA) can really be viewed as nutrient miners. They use their root structure to mine nutrients. They can have deep tap roots or an extensive underground network of rhizomes which translocate those minerals into their leaves.  Sometimes they are used to try to repair soil, whereby a DA that has a deep tap root can pull up nutrients, and when the leaves are dropped and mulched over the surface, they breakdown and become bioavailable near the soil surface.


Comfrey - Plant near compost bins or greenhouses for easy mulching and/or compost building.

Comfrey - Plant near compost bins or greenhouses for easy mulching and/or compost building.

Typically though, people are using DA’s to mine nutrients from nearby soil and then apply those nutrients to another area of a farm or garden. So imagine you have a farm and there’s edges of fields or gardens just sitting there covered with grass. So one would plant a row or swath of, let’s say, comfrey in that area.  Then the comfrey would mine the nutrients from that unused area and then the leaves could be mulched into the pots, beds or fields or amended into the compost pile. The comfrey could also be turned into liquid fertilizers or foliar sprays through the extraction processes of fermentation or sun teas.


Chamomile Sun Teas have been tested to be high in Ca, Mg, P, K, Na, S. This chamomile fermented plant extract was drip fed to these plants.

Chamomile Sun Teas have been tested to be high in Ca, Mg, P, K, Na, S. This chamomile fermented plant extract was drip fed to these plants.

One of the contended variables of DA’s is the technical science behind quantifying how much nutrients are actually stored. If nettle is good at accumulating iron, but there is no iron in your soil, hypothetically, then it won’t really store that element because it wasn’t there in the first place! Also, it is apparently unknown to science precisely how long it takes for nutrients to become bioavailable.  Once the leaves store the nutrients, and the leaves return to the soil, there is little science to quantify how quickly or how much is returned into bioavailable nutrients. Science tends to overanalyze everything and want’s answers before proceeding. So while the scientific community is trying to find the answers to DA’s, the biodynamic and regenerative cannabis communities are embracing DA’s and seeing very positive empirical results. The complexities of DA’s are just beginning to be understood. There are a number of charts online to view which DA’s accumulate specific elements. Even if some of the research is anecdotal, it can still provide a general understanding for those wishing to engage in this practice.

By: Russell Pace – President of the Cannabis Horticultural Association



~Humboldt Earth Technologies~

As growers we always seem to be searching for the next level. Larger yields, higher quality and ways to cut costs are the general directives we aim to achieve. Within this industry however, there seems to be an overuse of synthetic fertilizers with little understanding of the biological systems involved in nutrient uptake and disease control. Many inexperienced growers overuse synthetic fertilizers, hoping that more nutrients means higher yields. All that really happens is a massive salt buildup, which leads to dead microbes, nutrient lockout, a lot of flushing and heavy fungicide spraying.

Marijuana Venture - Eastern Washington farm goes green on a commercial scale

Walden Cannabis takes advantage of its massive property by reserving thousands of square feet for insectary beds and cover crops.

The farm’s size also allows Walden to utilize a system of crop rotation — somewhat of a rarity in the cannabis space. After each harvest, the company rotates its grow site to a new section of the property in order to maintain healthy soil....

Pesticide Article in Marijuana Venture

Pesticide Article in Marijuana Venture

We recently wrote an article fro Marijuana Venture Magazine on the problems with pesticides. Click this link to read about the potential health impacts of residual pesticides and why systemic pesticides might be lurking in your municipal compost.



Within the world of Permaculture we often find reference to plants known as Dynamic Accumulators. In brief, this is the idea that certain plants (often deep-rooted ones) will draw up nutrients from the lower layers of the soil, and these nutrients will be stored in the plants’ leaves. When the leaves fall in autumn and winter and are broken down, those stored nutrients are then incorporated into the upper layers of the soil where other plants will benefit from their deposition.

Making the most of an efficient HVAC system for Greenhouses

Great article from Cannabis Business Times...

A greenhouse brings a grow closer to the elements, but the same sun that feeds the plants can also push the temperature far past the comfortable range for cannabis.

One main consideration is whether the greenhouse will be “open” or “closed,” says Nadia Sabeh, agricultural and mechanical engineer for consulting/engineering firm Guttmann & Blaevoet. An open greenhouse has some form of air flow from outside the structure, while a closed greenhouse is structured more like an indoor grow and mostly sealed. But even though an open greenhouse has more interaction with outside air, it doesn’t mean the cooling strategy is ... just to open a window, she says.

Depending on the location of the greenhouse, natural, passive ventilation is an option with ridge vents or open side walls, which can be manual or automated, says Sabeh....



While regulators scratch their heads trying to figure out how to best
approach this topic, it’s clear that “business as usual” may turn into
“business unusual.” Many farmers groan as engineering fees, soil
tests, and permitting costs raise the price of going “legal”, but some
growers and professionals are nodding their heads in approval.

Shilajit - An Ayurvedic Powerhouse

Shilajit - An Ayurvedic Powerhouse

Often times I get the question, “How do I prevent my plants from getting sick?”. The
answer is simple, and that is through plant immunity. In short, there are two primary
factors that contribute to plant immunity:
1. Adequate Mineral Nutrition
2. Having that nutrition delivered in the form of microbial metabolites...

Product Spotlight - Grass Roots Grow Mats

Product Spotlight - Grass Roots Grow Mats

The CHA is happy to provide a spotlight on Grass Roots Grow Mats. They’re made from Hemp, which has been cultivated for fiber and food for over 10,000 years around the globe. The beautiful thing about Hemp is that it helps our planet and people throughout its entire life-cycle and then some! 

Grass Roots Grow Mats are now making hemp fiber grow plugs.  The CHA will be running experiments with them over the winter to determine the optimal parameters. Check out Grass Roots Grow Mats at:

One Bad Apple... Plant Growth Hormones and You. By: Luke A. Besmer

One Bad Apple... Plant Growth Hormones and You.  By: Luke A. Besmer

I am sure you’ve heard the old saying about how one bad apple spoils the bunch? Well it’s true, and of all things it’s due to a hormonal imbalance. Who’da thunk? So it turns out that in nature, the first ripe apple of the season drops to the ground and begins to decompose. During the decomposition process, the apple releases a gas called Ethylene. Ethylene is a Plant Growth Hormone (PGH) that triggers the nearby apples to fall to the ground and start the decomposition process. The sweet smell of all those decomposing apples attracts foraging animals who eat the apples and spread the seeds far and wide, often with a little fertilizer to boot (or conversely, to overwhelm scavengers so that some seeds are left undisturbed and able to safely germinate). Ethylene and other Plant Growth Hormones are vitally important to all aspects of plant growth and development, understanding them and their uses can improve any gardener’s yield.