By Get Edukated
Gardening, once considered a hobby of the older generations, has
come back into vogue. The increasing sales of houseplants in recent
years has been attributed to millennials discovering the joys of
easy-to-care-for miniature succulents and choosing houseplants over pets.
Trends in organic farming practices and locally-sourced produce, along
with a concern for the environment, have aligned with a renewed interest
in the cultivation of cannabis in the ten states where it has become legalized.
The market has become increasingly crowded as new companies
produce innovative new products that allow hobbyists access to the type
of technology once available only to professional growers. In this article, we
provide some basic advice for Kurple readers on how to get started with
cultivating cannabis as a hobby.
Look for the lesser-known strains that can
often be found at reasonable prices. The
higher-priced offerings offered by reputable
seed companies often reflect years
of careful breeding to stabilize a strain’s
scent, growth pattern, maturation rate,
and other traits. Less-reputable breeders
may offer similar genetics, but there will
be more variation among the individual
plants.
Cannabis seeds are now available in
many forms including regular, autoflowering
and feminized. Seeds labeled as “regular”
result in male and female plants. Autoflowering
and feminized seeds will result
in all-female seedlings. The autoflowering
varieties have the advantage of finishing
within 90 days. Autoflowering seeds have
improved in quality over the last decade.
Their uniform height, compact size, and
automatic flowering response makes them
ideal for beginners.
Cannabis seeds are also classified as indica
or sativa. Indica strains originated from arid,
mountainous regions like Pakistan, while
sativa strains have adapted to tropical
climates. Although the great majority of
strains are hybrids of both subtypes, often
one set of genetic features predominates.
Beginners should avoid selecting pure
sativa or predominately sativa seeds. The
tall lanky sativa-dominant strains require
precise training and pruning. In addition,
they often require longer periods of brighter
light and a slightly bluer light spectrum
compared to indicas. Prolonged flowering
cycles often exceeding 13 weeks, sensitivity
to cooler temperatures, and sensitivity
to excess nutrients further adds to the challenge
of successfully cultivating sativadominant
strains.
By contrast, many pure indicas complete
their flowering within 6-8 weeks. Their shorter
plant height, resistance to heat and cold,
and overall vigor make indicas a suitable
selection for newbies.
CONTAINERS & POTS
The ever-expanding selection of containers
available for growing can be intimidating
– especially for new growers. Plastic
pots, taller than they are wide, are still the
most popular and economical choice.
Their non-porous nature allows for easy
disinfection and superior moisture retention.
Because plastic pots retain moisture, seedlings
and small plants raised in plastic pots
should be watered sparingly.
Those with a tendency to overwater would
be advised to select pots made from clay, perforated plastic, or fabric pots. Fabric
pots are made from a synthetic fabric that
is permeable to water and air. They are
enjoying a period of rising popularity as
environmentally-conscious growers seek
alternatives to plastic containers. The sturdy
fabric promotes cooling of the soil through
evaporation. One drawback of fabric pots
is that it can be difficult to dislodge a rootbound
plant from the fabric sleeve. It may
be necessary to remove the stitches from
the fabric. Look for fabric pots that are
slightly tapered toward the base to allow
for easier transplanting.
The newest offerings in growing containers
include plastic pots that disassemble
and have walls made from a perforated
material. These perforations allow air to
circulate around the mass of soil to a much
greater extent than is possible in solid plastic
pots. The increased evaporation along
the surfaces of these types of pots allows
the soil to dry at a faster rate and promotes
healthy roots.
Clay pots have an even greater cooling
capacity and have the added benefit of
insulating the pot from extreme heat or
cold. In areas with very high summer temperatures,
clay pots provide a cooling effect
at the roots. Even as ambient temperatures
rise, the clay pots can keep the soil
up to ten degrees cooler. The porous nature
of the clay allows the roots to receive
increased amounts of oxygen through air
circulation in much the same manner as
plastic pots.
SUBSTRATE SELECTION
The bulk ingredient in most growing substrates
consists of coir or more commonly, peat moss. Coir is a substrate made from
the pithy outer layer surrounding the coconut.
Bark or compost may also be added
as bulk ingredients in many potting mixes.
For increased aeration and lightness, many
mixes incorporate perlite, vermiculite,
pumice, or coarse sand. While it is best to
choose a mix that contains added nutrients,
mixes that use timed-release pellets of
chemical fertilizers are less desirable than
those that use organic nutrients. Organic
amendments include compost, worm castings,
seaweed, and fishmeal, among others.
Some brands do not include fertilizer,
and it will be necessary to begin feeding
with a mild liquid fertilizer shortly after transplanting.
While brands of soilless substrates vary in
price and in nutrient amendments, one
particularly important factor is the soil
particle size. Particle size is related to bulk
density. Soils with larger particles are desirable,
but it is difficult to discern the size of
soil particles from the packaging. One general
rule is to choose mixes that feel light
within the bag and feel fluffy in consistency
through the bag. Heavy or dense mixes
tend to have smaller particle sizes and a
higher bulk density which means they will
retain far too much moisture. Lower quality
mixes tend to have a higher proportion of
dense components such as sand, topsoil,
or bark. Finely-ground peat will retain large
amounts of water and therefore must be
watered with great discretion. Coarse peat
is ideal, but it is rarely encountered in mixes
due to its high cost.
One renewable, earth-friendly alternative
to peat is coconut husk. Commonly called
coconut coir, it resembles coarse coffee
grounds in texture and tends to have the
moisture-retaining benefits of peat while
allowing for more air circulation. Because
of the chemical charges present on coir,
it requires a specialized pre-treatment
process and an adjusted fertilizer solution
higher in calcium and magnesium. Coir
can be tricky for beginners. An ideal compromise
would be to incorporate treated
coir into mixes that also include bark, peat,
or compost to minimize the effects of the
coir. Such a substrate can be treated as an
all-purpose mix.
LIGHTING
Light-emitting diode, or LED lights, have
dominated the market in the last decade.
Older LEDs were red and blue in color, but
the newer types provide a brilliant white
light. Newer COB-type LEDs are increasingly
common for their reliability, efficiency, and
lumen output. The prices of LED fixtures are
now comparable to other lighting systems.
Despite their seemingly cool temperature,
LEDs are still capable of burning the foliage
of plants if the lamp is too close to the
canopy. LEDs also produce a large amount
of heat, and ventilation is still necessary.
Smaller LEDs with a screw-in base have effectively
replaced CFL (fluorescent) bulbs
for raising seedlings and cuttings. Compact
LEDs produce minimal amounts of heat and can be conveniently positioned to
illuminate a small group of seedlings. Most
LEDs will last several years longer than the
HPS or metal halide lamps which usually
need to be replaced every 2-3 years.
HPS, or high-pressure sodium lamps are
nearly as efficient as LEDs and often more
affordable. The characteristic yelloworange
glow of an HPS lamp is due to the
high proportion of red light. Flowering cannabis
plants require red light and respond
favorably to HPS lamps.
Metal halide, ceramic metal halide, and
double-ended HPS lamps are among the
higher-priced fixtures and are usually reserved
for use in larger gardens. The efficiency
of double-ended HPS and the color
spectrum of ceramic metal halide lamps
are comparable to the best LED fixtures.
For younger seedlings and cuttings, a coolwhite
LED lamp is preferable to an HPS as
the blue light encourages lush leafy growth
and strong stems. Seedlings and cuttings
require the lights switch on for 16-18 hours
and off for 6-8 hour intervals. Flowering
plants require 12 hours of light and 12 hours
in complete darkness. For flowering cannabis,
choose a warm-white LED over a coolwhite
light to help ensure plenty of red light
is included in the spectrum.
TEMPERATURE
All lamps, particularly the HPS and metal
halide types generate large amounts
of heat and can quickly raise the temperatures
to dangerous levels within an
enclosed space that lacks adequate ventilation.
An ideal temperature range is between
70˚F and 84˚F. Cooler temperatures
will result in slowed growth and possible
nutrient deficiencies. Higher temperatures
cause all manner of problems from plant
stress to stunted growth and infestation by
spider mites. The effects of high temperatures can be
ameliorated by using oscillating fans to
circulate the air around the plants. An
in-line exhaust fan should be used to vent
the heat generated by the lamps from the
enclosed space. Increased air circulation
results in faster drying of the soil and
thereby reduces the incidence of root disease.
Ventilation also helps prevent mold
from forming within the floral clusters and
makes it difficult for pests like spider mites to
reproduce.
PH
The PH scale ranges from 0-14 and refers
to the acidity of a substance. A value of 7
is considered neutral and anything below
7 is acidic. Values above 7 are considered
basic. The ideal range is between 6.3 – 6.6.
The complexity of the chemical interactions
that give rise to a pH measurement
can be intimidating to a new grower. Yet
pH is of such fundamental importance
because it affects the ability of the plant
to absorb nutrients where the roots meet
the soil. Most nutrient deficiencies are not
caused by lack or fertilizer, but by a pH in
the substrate that is far too acidic or basic.
PH is mainly determined by three factors:
• The pH of the water used. Tap water
here in the desert Southwest tends to
be alkaline, that is it has a pH above
7 due to dissolved calcium and
bicarbon ate salts.
• The amount of lime used to amend the
soilless substrate. Most soil companies
use dolomite lime, which contains both
calcium and magnesium, to offset
the acidity of peat and to provide
the plant with enough calcium. Most
professional soilless mixes are prepared
with the
correct amount of lime to adjust the
pH to an ideal range.
• The type of fertilizer used. High-nitrogen
fertilizers, often used in the seedling
and early growth stages, tend to have
higher proportions of ammonium and
urea fertilizer. These fertilizers have an
acidifying effect on the substrate.
Fertilizers labeled as “hard water”
fertilizers take advantage of this
acidifying effect to compensate for
the high pH of most tap water. While
mostly used in hydroponic
applications, these types of fertilizers
have proven quite effective in main
taining an adequate level of acidity.
Most all-purpose or cannabis fertilizers
have balanced proportions of nitrogen
and ammonium and are therefore unl
ikely to affect pH drastically.
Since most high-quality soils and fertilizers
have a balanced pH, adjusting the pH
is mainly a matter of adding acid to tap
water to obtain a pH in the ideal range. A
color-indicator pH test can be easily obtained
for a few dollars from any aquarium
supply store or a garden shop
Using a one-gallon container, measure one
gallon of tap water, allow the water to sit
overnight in an open container to dissipate
the chlorine. Take a pH reading of the tap
water and slowly add citric acid, vinegar,
or a store-bought pH-down solution — a
quarter teaspoon at time. Stir the water
gently and allow it to rest for a couple minutes
before taking a pH reading. Repeat
the process until the pH reads just below 7.
Take note of the amount of acid used per
gallon. Thereafter, use the pre-measured
amounts to mix all solutions that will be used for irrigation. Agitating the water or allowing
it to rest several hours will likely raise
the pH back to the original reading, but it is
not necessary to add more acid.
WATERING
AND FERTILIZING
It is considered best to use at least some
proportion of tap water in the solution
used to irrigate plants. Tap water contains
many trace minerals such as calcium,
magnesium, copper, and zinc that may
not be fully provided by the fertilizers being
used. Some tap water is naturally high
in dissolved salts which can be verified by
testing the conductivity. Tap water in New
Mexico ranges from about 600-1200 ppm
which is considered higher than average.
A good compromise in places with very
hard tap water is to blend equal portions
of reverse-osmosis purified water and tap
water.
Overwatering is the most common mistake
made by beginning growers and even
some experienced gardeners. It leads to
symptoms like wilting and yellowing which
resemble nutrient deficiencies or dehydration.
A general rule is to water when the
top 1.5 – 2 inches of soil at the surface of
the pot are dry to the touch. Lifting the pot
and weighing the pot is also an acceptable
method of determining when the soil
has dried sufficiently. Using an accurate
scale to weigh the growing containers is
recommended for this method.
Determining the watering schedule requires
experience and skill. Both the total
amount of water applied and how often it
is applied will be different for each plant.
Among the factors that affect the watering
frequency are the porosity, drainage,
and moisture retention properties
of the substrate, the intensity of the
light source, the air temperature and
its relative humidity, the amount of
air circulation, the size and type of
pot, and the size, stage, and health
of the plant. Moreover, these factors
interrelated and dynamic — meaning
they will vary with time, season and
location. Be patient learning each
plant.
Peat-based mixes tend to retain large
amounts of water, so it is best to water
these using pre-measured amounts of
solution and allow a sufficient time interval
between watering events. It is best to experiment
using a specific soil and container
type to determine the adequate watering
schedule before germinating seeds. Large
plants in relatively small containers, outdoor
plants, or rootbound plants can dry quickly
and can therefore be watered more
generously and frequently. Transplant a
rootbound plant as soon as possible into a
larger container if this is feasible. Seedlings,
sick and recovering plants, or small plants
in large containers must be watered with
extreme care and allowed a good drying
period afterwards for best results.
Nitrogen, phosphorus, and potassium, or
NPK, are the main ingredients in fertilizer.
These are required in relatively large quantities
by all plants. Sulfur, calcium, and magnesium
are needed in moderate amounts.
Lastly, elements like iron, zinc, and copper
are needed only in trace amounts. Most all-purpose fertilizers supply all the nutrients
required for cannabis growth. Tap water
provides calcium and magnesium which
are not typically included in most all-purpose
fertilizers. Specialty cannabis fertilizers
often do include calcium and magnesium.
They are typically offered as a high-nitrogen
“vegetative formula” and a “bloom
formula” that has a reduced nitrogen content
and higher proportions of potassium
and phosphorus.
If a rootbound plant is transplanted into
properly amended soil, the roots will be
able to access the nutrients in the fresh
soil and additional applications of fertilizer
become largely unnecessary. While pelleted,
time-release fertilizers can be used
to amend soil, there is less risk of burning
the roots if organic amendments are used.
A high-quality organic fertilizer such as
Amigo Bob’s organic plant food is ideal
for amending store-bought soilless mixes.
The organic nutrients should be thoroughly
incorporated into the moistened soil. The
mixture should then be placed into a bag
or a bin and allow to rest for at least a
week. During this rest period, the organic
nutrients begin to break down and the
communities of beneficial microbes will
have the time to become established.
The only nutrient deficiency that is considered
acceptable in otherwise healthy
plants is a gradual yellowing of the oldest
leaves. This indicates the nitrogen reserves
of the soil are being depleted. If a cannabis
plant is already in the flowering stages,
such a deficiency is desirable and should
not be treated. In younger seedlings, this
usually indicates the soil used was not
amended with nutrients and a light feeding
with an all-purpose or vegetative formula
fertilizer is advisable.
Aside from a slight yellowing as described
above, a healthy plant should show no
evidence deficiencies such as cupped or
wrinkled leaves, stunted growth, yellow or
brown spots, burned tips or other abnormalities.
Often these symptoms are caused
by overwatering, over-fertilizing, extreme
temperatures, or most likely, inadequate
pH levels.
Most nutrient deficiency problems are
not caused by a lack of fertilizer. Nutrient
deficiencies arise when a plant becomes
rootbound, when it is overwatered, overfertilized,
or if the pH drifts due to the salts
present in untreated high-pH tap water.
In coir, deficiencies may arise if the water
used to irrigate the crops lacks adequate
amounts of calcium. Using a soil mix that
has not been amended with nutrients is
also a common cause of deficiency symptoms.
Adjusting the pH will resolve most
nutrient deficiencies that cannot be attributed
to extreme temperatures, inadequate
soil, or overwatering.
A FINAL WORD
Raising cannabis seedlings to maturity is a
rewarding experience, but it is not without
its challenges. Even experienced gardeners
encounter factors beyond their control
in the form of spider mites, mold, excess
summer heat, humidity, cold weather, or
power outages. Experience is the best
predictor of success, and the only way to
gain a bit of experience is through practice.
Beginning the process by learning to
grow a few easy houseplants or herbs is
an affordable and effective way to gain
confidence.
An indoor garden can be as simple as a
couple plants on a windowsill supplemented
by a small LED lamp, or a sophisticated
hydroponic operation with timers and
automatic watering systems. When managed
successfully, both have the potential
to bring equal amounts of satisfaction and
a sense of pride to the grower.
