(The following is for educational purposes only.  The author in no way
endorses nor condones the cultivation of controlled substances.  I do,
however, condemn narrow-minded legislators and law inforcement agencies
who continue to punish those who do.  Fro m my own experience, alchohol
and tobacco use are inherently more harmful and dangerous than is the
occasional recreational use of naturally-occuring psychoactive plants,
such as marijuana and psylocybin mushrooms.)


ROCKWOOL

Rockwool is inert, sterile, porous, non-degradable and offers plant
roots firm support and good oxygen access!  It also is lightweight and
ideal for hydroponic growing - where the grower has complete control of
pH levels and nutrients at all times.

Horticultural rockwool has been used for hydroponic growing in Europe
since 1969 and produces 50% of all their greenhouse grown vegetables. 
Yields have been recorded of up to 160 tons per acre, crop after crop,
with greenhouse tomatoes grown in rockwool.


Rockwool is an inorganic mineral product that was first discovered on
the islands of Hawaii in 1840.  These rockwool formations were created
as a natural by-product of volcanic activity.  For today's
horticultural industry it is either produced from rock  alone, or from
a combination of rock, limestone and coke.  The components are melted
at temperatures exceeding 2,500 degrees F.  This molten solution is
poured over a spinning cylinder.  As the molten solution flys off the
cylinder, it elongates and cools to form fibers.  These resultant
fibers (rockwool) are then pressed into sheets, cubes, blocks and/or
are granulated.  Granulated rockwool can be used as a soil mix
amendment or placed in plastic bags for bag culture.

Like all inert (with few or no active properties) media, rockwool acts
only as a temporary reservoir for nutrients supplied through the
irrigation water.  This allows the grower a tremendous amount of
control over plant growth through nutrition.  Also, ro ckwool's fibrous
structure contains a high percentage of air space; approximately 20%
even when it is fully wet.  There is little danger of overwatering
plants!  Since the fibers cannot bind nutrients or water (like peat
media can), all nutrients and wate r contained within the fibers are
available to the plant.  pH is also controlled by the irrigation water
and may be easily changed.

The basis of the nutrient solution used in a rockwool system begins
with the chemical composition of the existing irrigation water.  Once
the original water has been analyzed, fertilizer rates and pH additives
are determined.  A complete water breakdown ( specific levels of
chemicals) is necessary to make these determinations.  Because the
existing irrigation water forms the basis of the ultimate nutrient/pH
solution, any changes in water quality during the crop cycle may
require nutrient and pH adjustment s.  Contact your local agricultural
extension agency and they will inform you where to send your water to
get it tested.  They are familiar with the water in your area and will
give advice if there are any specific problems.  Testing is a must if
you are  taking water from a well.

It is recommended that you keep a daily record of your growing
environment, including the nutrient solution quality, for your first
crop using the rockwool system.  Monitor the air temperature, humidity
and carbon dioxide levels.  In the nutrient solution , monitor
temperature, pH, dissolved salts and fluid depletion levels.  This will
give you a "feel" for the needs of your plants and will enable you to
optimize conditions.  An inert media cannot buffer a growing mistake -
errors will be magnified and wil l appear much sooner than they would
if the crop were grown in peat or soil; growing in rockwool is much
more precise.

High temperatures during the manufacturing process make rockwool
disease, weed and insect free.  The process also creates a
non-degradable, long-lasting media.  Barring disease problems, rockwool
can be used for several successive crops.  However, residua l roots
from the previous crops decompose and can harbor pathogens.  In
commercial vegetable production, rockwool is usually discarded or steam
sterilized after two or three uses.

The key to growing record yields in rockwool is a matter of combining
its remarkable areation and nutrient holding capabilities with the
proper nutrients, temperature, lighting and CO2 levels to obtain the
ultimate growing environment for the crop.

GENERAL GUIDELINES FOR ROCKWOOL USE:

Prepare rockwool by thoroughly soaking it to capacity with the proper
nutrient solution.  Always apply nutrients to the rockwool before
handling the product.  If handling rockwool in a dry state, and working
in confined spaces, use a nuisance mask.  (Thes e cautions should also
be applied to perlite and vermiculite horticultural products.)  Keep
the rockwool growing medium moist - do not let the media dry out!  The
soluble salt levels will be thrown out of balance if the moisture
levels in rockwool are too low.  A good rule of thumb is to keep the
rockwool wet enough that nutrients will squeeze out easily.  Irrigate
20% to 30% more than needed to leach out excess soluble salts.  If
using a floor or capillary type irrigation system; the medium should be
tho roughly leached every two weeks - or sooner if salt build-up
appears to be causing problems with growth.

Soluble salts should be measured after the nutrient solution is added
to the rockwool media.  The propagation stage should be maintained
within the range of 450 to 650 P.P.M. (Parts Per Million) and the
growth stage should be kept between 1100 to 1425 P.P .M..  The
flowering (or fruit production) stage of plant growth requires that
enough nutrients will be available at the onset to produce maximum
yields.  Soluble salt levels should be between 1175 to 1300 P.P.M. at
the start of the bloom stage, tapering o ff on the concentration of the
nutrient solution gradually (over a few weeks) to a level of 975 P.P.M.
at the end of the flowering period.

The pH levels of the nutrient solution should be maintained at 5.3 to
5.7 pH in the reservoir.  When applied to the rockwool the pH will
raise to the range of 6.0 to 6.5, which is the ideal level for plant
growth throughout the cycle.

Temperatures need to be monitored in several different places to
accurately determine what is happening in the growing environment. 
Rockwool and air temperatures need to be in the 60 to 85 degree F
range, with the lower temperature at night (dark cycle).

If carbon dioxide and light levels are high; temperatures can be
increased to 85 degrees F during the day with a ten degree drop in
temperature at night.  These are guidelines and specifics will depend
mainly on the type of crop.  Temperatures for plant propagation are
generally maintained in the 70 to 75 degree F range until rooted. 
Seedlings are very specific and should be treated accordingly. 
Marijuana seedlings do well at temperatures from 75 to 85 degrees F.

Containers for rockwool can be of almost any size or shape.  A good
container for loose rockwool is the new root pruning pots in the one
gallon round or the three gallon square sizes.  Rockwool slabs come
wrapped in plastic and can be used as is.  After r ooting the seedlings
in a small cube, cut out a square of plastic the same size as the cube
and place the seedling on that spot.  Its roots will grow down into the
slab.  A slab 3 feet long will support 3 or 4 mature clones (plants
started from cuttings).

Horticultural tools to assist you in adequately monitoring your
hydroponic garden include a good pH meter (or paper strips), PPM gauge
(E.C. meter or dissolved salts meter), light meter, microscope or a
hand magnifying lens and a quality sprayer.

When applying insecticides and fungicides directly to the rockwool, cut
down the rate to 15% - 20% because of the lack of buffer activity (no
interaction with applied chemicals).

For hydroponic nutrients, a good hydroponic GROW and BLOOM formulation
is recommended.  Use these formulas at 1/2 strength for the propagation
and seedling stages of growth and the full strength nutrient solution
during the growth and bloom stages.

The following is a list of suppliers of rockwool, and many also carry a
full line of indoor horticultural products, including metal halide and
high pressure sodium light systems, hydroponic systems, CO2 injector
systems, vent fans, nutrient supplies, time rs, etc.  Beware of some
companies you may see advertised in magazines such as High Times. 
Although most are reliable firms, there have been some cases of DEA and
law-enforcement agencies putting ads for phony mail-order supply
houses, and after getting  your address, they set up surveillance of
you!  A good rule of thumb is to note how long they have been in
business (ads are expensive and most law enforcement agencies do not
continue these sting operations forever).  The firms listed below have
supplied my friends and I for a number of years and are legitimate.

SUPPLIERS:

Hydrofarm West
3135 Kerner Blvd.
San Rafael, CA 94901
(800) 634-9999 or (415) 459-7898

Berkeley Indoor Garden Center
844 University Ave.
Berkeley, CA 94710
(800)523-1367 or in Calif (415)549-2918

Hamilton Technology Corp.
14902 S. Figueroa St.
Gardena, CA 90248
(800) 458-7474

Energy Savers Unlimited, Inc.
22138 South Vermont Ave.
Building C
Torrance, CA 90502
(800)421-2994 or (213)328-6732

----------------------------------------
Mail order seeds (discretion assured)- BEST QUALITY from:

Seed Bank
Postbus 5, 65762A
OOY (UBB), Netherlands
(catalog free, shipped from within the U.S., so no customs search)

SSSC (Super Sativa Seed Club)
Postbus 1942
1000 BX
Amsterdam, Holland
(catalog $5, cash only - very informative also, shipped domestically as well)


SUGGESTED READING:

Marijuana Growers Handbook: Indoor/Greenhouse Edition by
Ed Rosenthal (1984) 251 pgs. $16.95

Indoor Marijuana Horticulture, Revised Edition by
Jorge Cervantes

Marijuana Botany by
Robert Connell Clarke  (220 pgs, $12.95)

           These books are available in most Tower Book stores, but
           if not, can be ordered from:
                Quick Trading Company
                P.O. Box 477
                San Francisco, CA 94101
                (800)428-7824 x 102


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