Rockwool the book


The number of people who grow cannabis for themselves keeps increasing. Some of them raise it in a small, modest garden for their own use; others for commercial reasons. A great deal of experimentation has been done with cannabis in The Netherlands, and through the years, further improvement took place.

Dutch weed can measure up to the best foreign varieties. After growing only in soil for years in The Netherlands, other growing methods can expect new interest. Some people grow on hydro-culture (granules), but also, growing on rockwool substrate occurs more and more. It is a clean, efficient way to raise cannabis. Relatively little has been written about growing on rockwool. Surprising, on the face of it, because in professional horticulture rockwool is being used since long. Growing cannabis on rockwool appears to go very well.

Who would have expected anything else from this indestructible weed? For this book, we have drawn from the experience of growers of the produce we ordinarily buy from the green grocers. The specific expertise of professional weed-growers is also used. Their advice is appreciated; - without mentioning any names. This book is meant for everyone who wants to grow cannabis at home. The emphasis is on growing on rockwool substrate, and on (semi-professional) climate control in the grow space. The first section takes a look at to the wanderings of cannabis throughout the world, and to how plants, in general, are cultivated. The second part is principally concerned with what is needed for growing cannabis indoors, and about the details of climate control. The third section deals with growth itself, with attention paid to plant diseases and insect pests.

We wish the reader enjoyable reading, lots of success at growing, and again, much pleasure with use

Middelburg, August, 1994

Luuk ter Aarde

Table of Contents

Foreword 3

glossary 7

Part I: Introduction<BR>
1. The history of cannabis 15
1.1. Preface 15
1.2. The journey 15
1.3. Marijuana in the Netherlands 16

2. Physiology of plants 19
2.1. Preface 19
2.2. Principles of growth 19
2.3. Osmotic processes 23
2.4. Intake and circulation of materials 26
2.5. Factors influencing the growth of plants 29

Part II: Necessities and climate control
3. Necessities and basic installations 30
3.1. Preface 30
3.2. The growing space 31
3.3. Shopping list 32
3.4. Growing space layout 35

4. Light 41
4.1. Preface 41
4.2. Choice of lamps 42
4.3. Using high-pressure gas lamps 46
4.4. Proper lighting for cannabis 47

5. Air 49
5.1. Preface 49
5.2. Influencing air quality 49
5.3. Relative humidity 53
5.4. Temperature 55

6. Water 57
6.1. Preface 57
6.2. Water quality 57
6.3. The irrigation system 64

Part III: Growing cannabis<BR>
7. Plant growth 70
7.1. Preface 70
7.2. Cloning hemp 70
7.3. The vegetative phase 77
7.4. The generative phase 79
7.5. Harvesting and drying 81
7.6. Skuff 83
7.7. Setting up the garden again 84

8. Diseases and insects 86
8.1. Preface 86
8.2. Diseases 87
8.3. Pests 90
8.4. Summary 96

Index 97


Acidity - Defines the measure for the uptake of nutrient salts by the plant. Acidity is indicated by the pH value.
A pH value of 5.8 is ideal for the cultivation of cannabis.

B - Abbreviation for boron, a material necessary in very small quantities for the growth of cannabis.

Blue light - Light given out by mercury-iodide lamps which is necessary for the formation of chlorophyll in plants.
Blue light has a wavelength of approximately 445 nanometers

Ca - Abbreviation for calcium; necessary for osmotic processes in the plant

Chlorophyll - The official name for 'leaf-green'. Chlorophyll gives the plant its green color,
and is important in the conversion of CO2 and H2O into glucose.

Clones - Weed-growers' jargon for cuttings.

CO2 - The chemical formula for carbondioxide; next to water, the most important basic material for the growth of plants.

C6H12O6 - Chemical formula for glucose, the basic material used by plants for growth and flowering.

Dark Part of photosynthesis. During response, the dark reaction, the actual formation of glucose from water and
carbondioxide takes place.

Deficiency Plant disease brought on by the disease-application of too little of a certain fertilizing material.

EC - Electrical conductivity. The electrical conductivity standard of water, which can be measured with an EC meter,
tells whether or not the composition of the fertilizer is correct

Fe - Abbreviation for iron; an element in the nutrient solution.

Generative phase - The flowering phase of plants. When cannabis is cultivated indoors, this phase begins, at maximum,
one week to ten days after a clone with roots is planted, and continues, depending on the variety,
two to three months.

GH - Abbreviation for 'German hardness', a scale for the hardness of water
(namely the quantity of calcium) indicated in degrees.

High- Cultivation under artificial light pressure makes use of high-pressure gaslamps.
They give out the desired quantity of light with the desired wavelength.
(High-pressure sodium lamps - red light for growth, mercury-iodide lamps -blue light for the formation of chlorophyll.)

H2O - Chemical formula for water, consisting of two parts hydrogen(H), and one part oxygen (O).

Hygrometer - A meter with which the relative humidity can be established<P>

Hygrostat - An apparatus which maintains correct relative humidity. A good hygrostat keeps the relative humidity constant in a room.

Internode - The distance between the leaves and the tops of a plant.
When light only from the red spectrum is applied during the generative phase, the internodes become longer.

K - Abbreviation for potassium, which is, next to nitrogen and phosphate, one of the primary nutrients for plants.

Light Part of photosynthesis in which response photolysis takes place.
Photosynthesis also includes the dark response, in which the actual formation of glucose occurs.

Lumen - The international measure for luminosity from a light source.

Ma - Abbreviation for manganese, an element used in very small quantities by plants.

Membrane- Membrane allowing small molecules to pass through but not the larger ones.

Mg - Abbreviation for magnesium, an element plants need for the build-up of chlorophyll, and for osmotic processes.

Micro-element - Nutrients the plant only barely needs; for example, copper and zinc.

Millisiemens- The international measure for electrical conductivity.

Nanometer - Measure of length used to express the wavelength of light.
Red light travels at a wavelength of approximately 650 nanometers(nm), blue light at approximately 450 nm.
A nanometer is one thousand millionth of a meter(10-8m).

NPK - Abbreviation for nitrogen (N),phosphate (P), and potassium(K), the three primary nutrients for plants.

Osmosis - The phenomenon in which water containing a dissolved substance of a low concentration is absorbed
via a membrane into water which contains substances of higher concentrations (for example in plants).
Osmosis is very important to plants for sturdiness, and for the transport of water and nutrient materials.
Pressure is built up by osmosis, making the plant sturdy. If this pressure falls, the plant loses its sturdiness.

P - Abbreviation for phosphate, one of the three primary nutrients.

pH - The pH is a measure of the acidity of a solution (for example, water with nutrients).
The pHscale goes from 0 to 14.
The lower the pH value, the more acidic the solution

Photolysis - Part of photosynthesis, in which water (H2O) is split up into hydrogen (H), and oxygen (O).
This occurs during the light response.

Photosynthesis - The chemical process in plants, in which carbondioxide and water are converted into glucose
by the influence of light energy

Phototropism- The inclination, which plants have, to grow towards light<P>

Physiology - The science of growth. (Plantphysiology is the science concerned with the growth and flowering of plants)

ppm - 'Parts per million'.
The amount of material in the air, of CO2, for example, is expressed not only in percent,
but also in ppm. 0.03% CO2 in the air is equivalent to 300 ppm.

Predator - A predator is an insect that protects plants against other insects such as spider mites, white flies, and thrips.

Red light - Light needed by plants in order to grow. Red light has a wavelength of approximately 650 nanometers.

RH - Abbreviation for relative humidity. The relative humidity is expressed in %, and measured with a hygrometer.

S - Abbreviation for sulphur, a nutrient which plants need only in small quantities.

Salts - Nutrients, such as NPK, but also other materials (Ca, Mg, etc.) which are dissolved in water so
they can be fed to the plant. We call the solution of such materials salts.

Semi-permeable walls/membranes permeable - Play a role in osmotic processes in plants by which the transport of water
and nutrients takes place, and the plant gets its strength.

Skuff - Sifted tops, from which you get as-pure-as-possible THC.

Stoma - An organ in the leaves of plants. The stomata allow the plant to breathe. Oxygen and excess water are
released through the stomata.

Substrate - The 'soil'. Thus rockwool substrate means 'soil of rockwool'; the growth medium.

T-44, T-77 - Measures for sieves with which you can sift out THC resin.

THC - tetra-hydro-cannabinol.

Trace-element - Another name for micro-element, nutrients the plant needs in only minute quantities, such as boron and manganese.

Vegetative- The growth phase of plants.
This lasts phase - only a short while in the cultivation of cannabis;
from one week to ten days maximum.

Zn - Abbreviation for zinc, a nutrient which plants need in small quantities.

PART I: Introduction


Chapter 1: A Short History of Hemp in the Netherlands

1.1. Preface

This book is not about the enjoyment of smoking or eating marijuana and hash. We can conclude that the home grower knows how to estimate the value of his or her own product, can't we? We'll just leave those stories about the nice feeling for what they are. We spend no time on the effects of cannabis products. Everyone knows what a good 'high' feels like; what you have to do, and what you sometimes have to allow to happen. This first chapter deals with the history of cannabis in the Netherlands. This way, you get a little insight into how the plant has come about in the Netherlands, and what purposes the cultivation of cannabis has served in the last centuries.

1.2. The journey

China is known principally for its tea and opium, the great number of its people, and the hughe amount of Chinese restaurants. also hemp originates from China. The Chinese were already cultivating cannabis 4500 years BC. They were able to spin yarn for clothing, and make fishing nets and rope with it. The first medicinal applications were described two thousand years later. It was used for rheumatism, gout, malaria, and a number of other disorders.

overfertilized plant

From China, hemp travelled to Arabia, and appeared in the writings of the Greek philosopher Herodote. He describes ritual use of burning hemp by the Syrian Skytes.
Hemp grows everywhere. It came to Europe via India and the Roman Empire. In the Middle Ages, hemp's intoxicating effect was described by Boccaccio and Rabelais, among others. Later, it was used by Victor Hugo, Honoré de Balzac, and Alexandre Dumas in the Latin Quarter in Paris.

Scholars do not agree as to whether the Spaniards were the original importers of cannabis to America. It is certainly true that Colombus' ships were outfitted with hemp rope, and sails made from hemp cloth. The plant spread quickly in America, and at the beginning of the seventeenth century, large-scale hemp plantations proceeded in order to supply the needs of the ship- and clothing industries.

1.3. Marijuana in the Netherlands.

It wasn't any different in the Netherlands. It's not exaggerated to suggest that a considerable portion of the wealth of the Golden Age came from the cultivation of hemp. Some 11,000 ships sailed at that time, rigged with rope and sails made of hemp. Hemp was the leading agricultural product in the Netherlands; the stalk was primarily valued. The stalk, only from the male plant, was processed into hemp fiber. The female plants were used for other purposes. These were harvested later, and then threshed. The seed was used as bird feed, or was processed into oil, green soap, and raw material for paint. For the latter application, a thick pulp remained which served as animal food. After the Golden Age, less and less hemp was cultivated in the Netherlands. Competition arose from cheaper Russian hemp, along with other fibrous materials such as coconut and sisal. The steam engine made its entry, so less rope and sails were needed in the shipping industry.

Just as in other countries, the medicinal effects of the plant did not go unnoticed by its growers. Rumours had it that witches used hemp in their witches' salves. The effects of hemp had already been described in "The Herb Book" by Rembert Dodoens in the sixteenth century.

Using cannabis products for pleasure really didn't come about in the Netherlands until after the Second World War. After jazz, and later the hippie influences, marijuana smoking blew over from America. In 1962, Simon Vinkenoog a Dutch liberated poët, wrote: 'In ten years, this will be as common as drinking whiskey or beer, or just as normal as an ordinary cigarette. And it doesn't give you lung cancer'. In the first decades, youbetter smoked imported hash than 'Nederweed'. Still, growing at home was so energetically pursued, that, thirty years later, Dutch weed ranks as the best in the world. There has been improvement, cross breeding, and cloning; fighting the currents, at first. Until the mid-Seventies, growing, possessing, and use of soft drugs was still punishable. Not until after the mid-Seventies tolerated points of sale originated - the coffeeshops.

CO2 intake in the leafs Light, air and water, the bare necessities

And now it seems there's no stoppping it. more and more of people use soft drugs, and more and more people try to hold down the costs of soft drug use by going to work for themselves. Sometimes, purely for their own use, sometimes to earn a few cents, sometimes to get rich.

This book has been written for the growing group of people who want to apply themselves to home cultivation. Now, this is the place to give a few warnings. In the first place, it may be generally presumed that smoking is not considered the best thing for your health. In the second place, even though the Dutch government has become more open-hearted in its tolerance of the growth, possession, and use of cannabis, the substance still stands on List 2 of the law on narcotics.

That doesn't pose a problem anymore, if it's for your own use, but for large-scale growing, possession, and dealing - it still does. Grow-gardens, green-houses, and plantations are still searched out and destroyed, and a considerable fine usually follows. Ultimately, every home grower has to gain knowledge and experience before there can be talk of a good yield. So, don't get discouraged too quickly if it doesn't go perfectly in the beginning

Next  Chapter

Back to Rockwool Index

Back to BC Growers Main Page

Link to the Authors of this Book