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A phosphorus deficiency in cannabis plants is a very common problem and tends to occur in the lower parts or the older parts of the plant. The leaves in the lower parts may get dark green or yellow color or might even develop big blue splotches. The affected leaves may thicken up and feel very stiff. At times, the plant stems might as well turn purple or red. However, if there’s calcium deficiency then both phosphorus and calcium might display reactions. 

Symptoms of phosphorus deficiency in the cannabis plant

¤ Lower and older leaves of the plant are affected

¤ Sometimes phosphorus deficiency comes with red stems but if there are no other symptoms then you might not have to worry much

¤ Leaves tend to darken and seem shiny

¤ If phosphorus deficiency is untreated then leaves may turn yellow in some places

¤ Leaves develop purple or brown splotches

¤ Leaves become thick and dry

¤ Phosphorus deficiency occurs mostly after buds are formed and at this time, the plant uses a lot of phosphorus.

At the flowering stage, the cannabis plant needs a lot of phosphorus and it is quite unlikely that a cannabis plant would get excess phosphorus through standard nutrients. However, if you still see phosphorus deficiency in your cannabis plant, then it’s probably a root pH issue that needs to be fixed. You must also know that some cannabis strains naturally have red or purple stems and so you shouldn’t mistake them for phosphorus deficit.

Solutions for phosphorus deficiency in the cannabis plant

¤ You have to start by adjusting the pH to a proper range. pH imbalance of the cannabis roots is the primary reason causing phosphorus shortcoming. Flushing the entire system with pH’d water is a good way to add more nutrients.

¤ You also need to take proper care of the roots and make sure that the soil is not too compact or over drenched

¤ Keeping your cannabis in cooler temperature or in places with too much of temperature swings can make it tough for the plant to absorb nutrients and phosphorus

¤ Give your cannabis the right amount of phosphorus and other nutrients

Some of the sources of phosphorus are

© fish meal

© worm castings

© blood meal

© Cannabis-friendly flowering nutrients

However, you must remember one thing that overfeeding your cannabis with phosphorus may have had consequences. Taking good care of your plant roots and watching for signs of recovery is what you can do best for your phosphorus-deficient cannabis plant.