pH And Marijuana Grown 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 garden.
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 the foliage.
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 center.
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 manufacturers instructions.
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.
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