Marijuana (Cannabis)

Hydroponic Nutrient Strength


Here are various ranges of nutrient strength that have worked best for the author of this guide. The amounts are low compared with some other recommendations. You can vary the amount but here are some possibilities to consider.

Starting seed/clones: 000-200 µS or 000-100 ppm (NaCl)
Rooted seed/clones: 200-600 µS or 100-300 ppm (NaCl)
Early veg: 400-800 µS or 200-400 ppm (NaCl)
Late veg: 600-1000 µS or 300-500 ppm (NaCl)
Early flowering: 800-1200 µS or 400-600 ppm (NaCl)
Late flowering: 1000-1400 µS or 500-700 ppm (NaCl)
Last 4-7 days: 000-700 µS or 000-350 ppm (NaCl)

The optimal nutrient strength gradually increases as a plant matures. There are also other factors to consider when adjusting the nutrient strength.

Aim for lower EC or TDS readings if;
the temperature is over 76°F/24°C.
the relative humidity is below 60%.
the light is under 600 watts.

Aim for higher EC or TDS readings if;
the temperature is between 70-76°F/21-24°C.
the relative humidity is at or over 60%.
the light is 600 watts or more.

Higher temperatures and lower humidity levels cause a plant to transpire and evaporate more water. If a plant processes more water, the concentration of nutrient increases. With lesser amounts of light the plant requires less nutrient.

During first 1-2 weeks, before a seed or clone has rooted, use a very mild (10% or less of the amount when flowering) nutrient solution. Some hydroponic growers don't add any nutrients until the root and first leaves start growing.

During the last 4-7 days prior to harvest most growers won't add nutrients, or will add nutrients at half strength or less. This is to flush nutrients from the plants, it is optional but recommended.

An EC or TDS meter is essential when growing hydroponic marijuana for giving you the ability to measure the amount of dissolved solids in nutrient solution.

This will let you know if the nutrient level has to be adjusted to keep it within the proper range, and will allow you to maintain an optimal level for the plants.

You can increase the EC or TDS meter reading by adding more nutrients to the nutrient reservoir. You can decrease the EC or TDS meter reading by diluting the nutrients in the reservoir by adding more water.

Always take an EC or TDS reading after the nutrients have been added to water, or just after hydroponic nutrient solution has been added to the reservoir. Check the nutrient strength in the reservoir at regular intervals.

If the tips of the leaves turn yellow or brown and dry out during early stages of life, it could be an indication that the nutrient level is too high and/or the relative humidity level is below 40%.

During flowering it is more common for the tips of leaves to dry out. Leaves tend to look more ragged as the plant gets deeper into flowering, because plant energy is focused on flowering, rather than growth.

It is normal for leaves at the bottom of the plant to totally turn yellow and die if they don't get enough light. When this happens cut off the yellow leaves at the stem with a pair of sharp scissors.


Part 01) See the full hydroponic marijuana nutrient article here.
Part 02) Nutrients and hydroponic marijuana introduction here.
Part 03) Water and hydroponic nutrients here.
Part 04) Preparing hydroponic nutrients here.
Part 05) Measuring hydroponic nutrient solution - EC, TDS, PPM here.
Part 06) Hydroponic nutrient strength here.
Part 07) Hydroponic nutrient solution temperature here.
Part 08) Flushing or leeching hydroponic nutrient here.
Part 09) Amount of water for hydroponic marijuana plants here.
Part 10) Hydroponic nutrient list of materials here.