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Marijuana Plant nutrient uptake

Marijuana Plant Nutrient Uptake

Let’s start with understanding the PH and EC reading

pH stands for Potential Hydrogen and is a measure of the concentration of hydrogen ions within a solution like water. pH is measured on a scale of 0 to 14 with 0 being acid, 7 is neutral and 14 is alkaline. A substance that when added to water increases the hydrogen ion concentration will cause the pH level to drop. This is known as a acid.

A substance that reduces the concentration on hydrogen ions and causes the pH to rise is known a base. There are also some substances that can enable the solution to resist pH changes when an acid or base is added. These are known as buffers. Buffers are very important in helping organisms maintain a relatively constant pH and they are also used to calibrate your pH meter occasionally.

More on pH meters here!

If the pH of your nutrient solution is too high (alkaline) or too low (acidic), it can restrict the uptake of nutrients through the roots of your plants. Many different variables such as evaporation, amount of light and temperature can affect pH levels.

Most plants can accept a pH range of between 5 and 7 (depending on the media you choose to grow in). Any extremes either side of that range will cause the plants to be blocked from certain nutrients. In low light, plants take up more potassium and phosphorus from the nutrient solution so the acidity increases (pH drops). In strong intense light, plants take up more nitrogen from the solution so the acidity decreases (pH rises). Any extremes of pH can also result in precipitation of certain blocked nutrients.

For plant roots to be able to absorb nutrients, the nutrients must be dissolved in a solution. The process of precipitation (the reverse of dissolving) results in the formation of solids in the nutrient solution, making the nutrients unavailable to the plants. Precipitation can also take the form of an almost invisible film of an oily look on the surface of your water.

EC stands for Electrical Conductivity and is a measure of the strength of the nutrient solution. The higher the conductivity, the more dissolved solids there are in the solution. EC is just one format of measuring the nutrients. It can also be measured in PPM (Parts Per Million), and TDS (Total Dissolved Solids). EC is the standard these days and is used in Canada, Europe, and most other places…
More on EC meters here!

Plants at different stages of growth need different amounts of food in their solution. Delicate plants like cuttings and seedlings requre the EC to be quite low so as to avoid fertilizer burn from over-feeding.

As the plant gets older the food concentration can be increased (EC raised) so the plants have access to more nutrients in the water. Low conductivity at this point or low strength nutrient solutions will result in nutritional deficiencies and slow growth rates of your plants.

EC can be affected by many variables too. Evaporation, temperature and ventilation are all factors that affect the EC level in your solution aswell.

Below you’ll find a marijuana plant nutrient uptake schedule which shows exactly which nutrients are available at a certain pH range. This is a great help keeping your plants healthy.

nutrient pH chart
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