" pH And Marijuana (Cannabis) "
pH is measured
on a scale from 1.0 to 14.0. Pure water has a pH of 7.0 and is
considered pH neutral. pH below 7.0 is considered to be acidic and pH
higher than 7.0 is considered to be alkaline.
A substance that
decreases pH (pH-down) is called an acid while a substance that
increases pH (pH-up) is called a base. A substance that helps nutrient
solutions resist pH changes when an acid or base is added, is called a
A pH difference of 1.0 is equal to a ten times
increase or decrease in pH. That is, a nutrient solution with a pH of
6.0 is ten times as acidic as a nutrient solution with a pH of 7.0. A
pH difference of 2.0 is equal to a hundred times increase or decrease
It is very important to keep the pH level within
certain limits when growing marijuana. Even first time marijuana
growers need to monitor the pH of their nutrient solution or soil and
keep it within optimum levels.
The pH level of your hydroponic
nutrient solution or soil will determine how well your plants are able
to absorb nutrients. If the pH level is out of the proper range, the
growth rate of the plants will slow down or stop.
"Checking The pH Level Of Marijuana"
There are several means of checking the pH level of your hydroponic or soil garden. See this for information about obtaining pH measuring and adjusting equipment.
--- pH Meter: used to measure the pH of water, hydroponic nutrient solution, hydroponic media, and soil.
--- pH Test Kit: used to measure the pH of liquids like water or hydroponic nutrient solution.
--- Soil pH Meter: used to measure the pH of soil.
--- Soil Test Kit:
used to measure the pH, nitrogen, phosphorus and potassium levels of
soil. There are also soil pH test kits available that just measure the
pH level of soil.
First time hydroponic
marijuana growers should get a simple pH test kit to check pH levels.
They are cheap, easy to use, and can be used multiple times. However,
you will eventually run out of pH test liquid and have to buy a new
They work by putting a small amount of nutrient solution
in a container then adding a few drops of pH test liquid and mixing
them together. The combined mixture will turn color. This color is then
matched with the color on a pH chart (included with the test kit) to
determine the pH level of the nutrient solution.
A pH meter
can be used to measure the pH of water, hydroponic nutrient solution,
hydroponic media, and soil. If you have been growing hydroponic
marijuana for a few years and you are tired of buying and re-buying
test kits, it might be best to invest in a pH meter.
meter is long lasting, and in general they give more accurate results
than other methods of measuring pH. But the price may make them out of
reach for first time growers on a budget. They also have probes and
batteries that eventually will need to be replaced.
accurate measurements always follow the manufactures instructions for
calibrating, cleaning, and using a pH meter. Calibrating the meter is
especially important because all measurements will be wrong if the unit
Because pH meters can measure the pH of
water, hydroponic nutrient solution, hydroponic media, and soil they
are strongly recommended for growers who use hydroponics to grow
indoors and soil to grow outdoors.
should get a soil pH meter to measure the pH level of soil in their
garden. They work by inserting the probes of the unit directly into the
soil you are growing in, and taking a reading. Follow the manufacturers
instructions included with the soil pH meter you use, and you will get
years of accurate measurements.
An alternative for soil
growers is a soil test kit. These are easy to use and reliable kits
that contain separate tests for pH, nitrogen, phosphorus, and
potassium. They give instant results on the soil conditions in your
A single soil test kit will have a certain number of
tests that can be preformed before you run out and have to buy another.
For example, one company makes a soil test kit that can be used to
check pH, nitrogen, phosphorus, and potassium levels in soil 10 times.
"pH And Hydroponic Marijuana"
When growing hydroponic marijuana the pH of the nutrient solution
should be between 5.5 and 6.8. In most cases optimal pH is about 5.8 to
6.3 but this may vary slightly depending on the particular marijuana
strain and the growing conditions you provide.
report good results with pH as low as 5.0. You can experiment to see
what works best for your particular plants but always keep the pH
between 5.0 and 7.0.
Measure the pH right after you add the
nutrient solution to the reservoir (mix well first) because the
nutrients will change the pH level of the water. Check the pH level
about once a week.
"Adjusting pH of Hydroponic Setup"
pH-up and pH-down solutions are used to adjust the pH level of
hydroponic nutrient solution and hydroponic media when the pH is out of
range. pH-up (also called pH increase) is used to raise the pH level
and pH-down (also called pH decrease) is used to reduce the pH level. A
pH-up or pH-down solution for hydroponic or aquarium use is
For hydroponic applications, nitric, phosphoric
or citric acids (even vinegar) can be used to lower pH, while potassium
hydroxide can be used to raise pH. If you understand what you are
doing, you can use them instead of buying pH-up and pH-down solutions
(contributed by james and jorge).
However, if you aren't sure
of the correct amount of acid or base that is needed to adjust the pH
to optimum values, it is best to buy a solution specifically made to
raise or lower the pH and carefully follow the manufacturers
Unless directed to do so by the manufacturer,
don't try to adjust your pH by more than 0.2 per day. Make drastic
changes over a number of days. If your pH is 7.0 and you would like it
at 6.5, try lowering it by 0.1 a day for 5 days (or do it even more
gradually). Overcompensating can spell disaster for your garden.
"pH And Marijuana Growing In Soil"
When growing marijuana in soil the pH of the soil should be between 6.5
and 7.0. When growing in containers, a single pH reading for each
container is recommended. When growing outdoors in a garden, it is best
to take two or three pH measurements from different areas of the
If you have a large garden, you may have to adjust the
pH in various parts of your garden to different levels. Check the pH
once every one-two weeks.
Unlike hydroponics where the
nutrient solution is in a single reservoir and only needs to be checked
once, a soil garden will get its nutrients from the soil it is growing
in. Even a small garden that contains a few plants may have soil that
varies in pH from one area to another.
Most fertilizers cause
a pH change in the soil. Adding fertilizer to the soil almost always
results in a more acidic (lower) pH. As time goes on, the amount of
salts produced by the breakdown of fertilizers in the soil causes the
soil to become increasingly acidic and eventually the concentration of
these salts in the soil will stunt the plant and cause browning out of
Also, as the plant gets older its roots become
less effective in bringing food to the leaves. To avoid the
accumulation of these salts in your soil and to ensure that your plant
is getting all of the food it needs, you can begin leaf feeding your
plant at the age of about 1.5 months.
Dissolve the fertilizer
in water (worm castings mixed with water will work well for leaf
feeding) and spray the mixture directly onto the foliage. The leaves
absorb the fertilizer into their veins. If you want to continue to put
fertilizer into the soil as well as leaf feeding, be sure not to
overdose your plants.
"Adjusting pH of Marijuana Grown In Soil"
A good way to stabilize soil is to use dolomite lime (calcium-magnesium
carbonate). Dolomitic lime acts slowly and continuously, so soil will
remain pH stable for a few months.
Using fine size dolomite
lime is important, coarser grades can take a year or longer to work.
You can find fine size dolomite lime at any well stocked garden supply
Dolomite lime has been used by gardeners as a pH
stabilizer for many years. It has a pH that is neutral (7.0). When
added to soil in the correct proportions, it will stabilize soil at a
pH near 7.0.
When growing in containers, add
one cup of fine dolomite lime to each cubic foot of soil. Mix the dry
soil thoroughly with the dolomite lime, then lightly water it. After
watering, re-mix it and wait for a day or two before checking the pH.
When growing in an outdoor garden, follow the dolomite lime
Lowering soil pH: small amounts of composted leaves, cottonseed meal, or peat moss will lower the pH of soil.
Raising soil pH:
small amounts of hardwood ashes or crushed oyster/egg shells will help
to raise the soil pH. Hydrated lime can also be used to raise the pH of
soil. In containers, use no more than 1/8 cup of hydrated lime per
cubic foot of soil (per application). Mix it into warm water, then
apply the water to the soil. When growing in an outdoor garden, follow
the manufacturers instructions.
Wait at least a day or two
before checking the pH level of soil after attempting to raise, lower
or stabilize it. If adjustments still have to be made, use small
amounts of whatever material you are using. Don't try to adjust the pH
more than 0.1 every two days.