The importance of the quality of the irrigation water in cannabis cultivation

The quality of the water used in cannabis growing is a determining factor which affects the growth of the plants. The essential nutrients found in the substrate are only available for the plants when dissolved, so the quality of the water affects the way in which these mineral compounds are absorbed by the roots. What’s more, cannabis needs lots of water to develop properly, so monitoring parameters like pH or electroconductivity (EC) is vital to obtain a successful crop. So, what’s the best irrigation water for your marijuana plants?

The water used to irrigate the plants must meet certain criteria of quality. In general, the most important parameters that need controlling are the amount of dissolved salts and the pH level.

Water is considered to be ‘soft’ is it contains less than 50 mg / litre of calcium, and in this case it would be necessary to add calcium and magnesium to raise the levels to 100-150 mg / L.

When the water is very hard, above 180 mg / L, it is necessary to use descaling or reverse osmosis filters to reduce the hardness. This avoids the precipitation of salts on the surface of the roots which can cause toxic effects.

Another issue of very hard water is that the salts saturate the water, leaving no space for the added fertilizers which then hinders the nutrition of the plant. In order to determine the salt quality of the water, its electrical conductivity (EC) can be measured. Good quality water has between 200 and 350 μS / cm (microsiemens per centimeter), allowing a very wide margin for the addition of fertilizer. When the fertilizer is added, the EC will increase to a value of 1.2 μS / cm during the vegetative period and up to 1.8-2.0 μS / cm at peak flowering period. The pH of the water should be slightly acidic for a correct transportation of all nutrients, the optimum pH being between 5.8 and 6.5 for hydroponic systems and between 6.5 and 7.0 for earth-based systems.

From Kannabia Seed Company, as a marijuana seeds bank, we would like to state the following items in accordance with current legislation in force in Spain:

1. That cultivation should only be for personal supply and consumption.
2. That the use and purpose of your cultivation must be therapeutic.
3. That the plantation should be carried out in the privacy of your own home, similarly the  consumption.

And most importantly, all information that is given references a small cultivation.