It is obvious that phosphorus deficiency could do some damage to the health of your plants and their potential yields. There are quite a few different symptoms to look out for that could signal phosphorus deficiency within your crop. First of all, the deficiency will usually start to affect the older leaves that are lower down on plants. These leaves may begin to exhibit a shiny appearance and turn to darker shades of green, blue and grey. Along with this change in colour, leaves will also start to develop purple and brown spots. Leaves will also become very dry and begin to thicken. The stems of the plant may also begin to turn bright red or purple.
Try to remain calm if you notice a phosphorus deficiency setting in. Panicking and adding far too much phosphorus back into the soil could prevent your plants from uptaking other nutrients and end up doing more harm than good.
One factor that growers must constantly be aware of when cultivating their plants is the risk of nutrient deficiency. Cannabis plants require an array of important nutrients that carry out vital biological functions throughout the grow cycle. If a certain key nutrient is missing during the vegetative or flowering stages, plants will start to display symptoms of deficiencies. These signs can help growers determine what is missing and therefore, what needs to be added to the soil before it is too late. One of these vital nutrients is phosphorus.
Phosphorus plays an important role in the health of all living organisms. Plants require this nutrient in order to achieve normal growth and to reach maturity. Phosphorus contributes to the DNA of the plant, as well as the RNA, which reads the genetic code in order to build proteins and other structures. Phosphorus is also vital in the creation of ATP, the unit of energy that plants use during photosynthesis. Phosphorus helps to stimulate root development, increase the strength of stems, improve flower formation and seed production, improve the quality of crops, boost resistance against diseases and support development throughout the overall growth cycle.
Temperature is another detail to pay attention to in order to achieve optimum phosphorus levels. Lower and colder temperatures can make it more difficult for your cannabis crop to absorb adequate levels of the nutrient. Temperatures that drop below 15 degrees Celsius may start to cause negative effects.
One cause of a phosphorus deficiency is the pH of the roots. A root pH between 6.2 and 7 is best in order to maximise absorption of the nutrient. Therefore, it is ideal to strive for a soil pH between this range when deficiency symptoms manifest. This can be achieved by using pH up and down products.
Phosphorus is a vital nutrient required by cannabis plants that fulfills many important biological functions. There are numerous different signs of deficiency symptoms to look out for when it comes to this nutrient.
An organic fertiliser containing adequate amounts of each vital nutrient can also be used to ensure that your plants are receiving the proper levels of phosphorus that they require. Additionally, other sources of phosphorus can be added to the soil in order to maximise exposure. Good source of phosphorus include warm casting, fish meal, crab shell and soft rock phosphate. Overwatering and compact soil can also be causes of phosphorous deficiency. Be sure to water your plants correctly to avoid this.
If your plants have fallen victim to phosphorus deficiency symptoms, you will notice a recovery stage take place if you take the right steps to restore the health of your plants. The spread of brown spots, red and purple stems and other symptoms will stop effecting new leaves. Don’t worry if old leaves do not recover, as this is normal.
Phosphorus plays many vital roles within cannabis plants and is needed in order to build proteins, provide energy and for normal growth.
A cannabis phosphorus deficiency usually appears with some or all of the following symptoms:
Phosphorus (P) is used by your cannabis plant in all phases of growth. It is one of the 3 major nutrients (N-P-K) listed on the front of most nutrient bottles, and phosphorus will be represented by the second number that appears.
If you’ve tried everything else, then you may try adding a higher percentage of phosphorus to your feeding schedule and see if that helps clear up the problem for your plant. Cannabis plants love phosphorus, and therefore it is unlikely that you will give your cannabis too much phosphorus.
Notice that the stems or veins never turned red or purple on this leaf, except for some parts that were actually affected by the phosphorus deficiency.
If you suspect your growing cannabis plant has a phosphorus deficiency, flush your system with clean, pH’d water that contains a regular dose of cannabis-friendly nutrients that includes phosphorus. This will remove any nutrient salts that may be affected the uptake of phosphorus and help restore pH to the proper levels.
Sources of phosphorus:
- In soil, phosphorus is best absorbed by the roots in the 6.2 – 7.0 pH range (in soil, it’s generally recommended to keep the pH between 6.0 – 7.0, but phosphorus specifically tends to be best absorbed above 6.2 and below 7.0)
- In hydro, phosphorus is best absorbed by the roots in the 5.5 – 6.2 pH range (in hydro, it’s generally recommended to keep the pH between 5.5 – 6.5, but phosphorus specifically tends to be best absorbed below 6.2)
Most growers have actually already given plenty of phophorus to their cannabis plants since it is found abundantly in quality soil and cannabis-friendly nutrients. However, even if you are giving phosphorus, it’s important to give your cannabis the right ratio of nutrients.
- tends to affect the lower and older leaves of the plant
- sometimes a phosphorus deficiency is accompanied by bright red stems (though not always), though if you have red stems but no other symptoms, it’s typically not something to worry about
- leaves darken (turning a dark green, blue or grayish color) and may appear shiny
- leaves may start turning yellow in places if the phosphorus deficiency is left untreated, or if the deficiency is combined with other nutrients deficiencies and/or pH problems. However, yellow leaves is typically not associated with the beginning of a phosphorus deficiency.
- leaves get bronze, purple or brown spots and splotches
- leaves thicken and may feel dry or stiff
- stems sometimes turn bright red or purple, but not always
- sometimes accompanied by a Calcium deficiency, as Phosphorus and Calcium interact with each other inside the plant
- this deficiency is more common after buds start forming, when the plant is using a lot of Phosphorus
Phosphorus deficiencies cause dark splotches on leaves and can appear at the bottom of the plant on some of the oldest leaves. Learn to spot & fix the issue.