Cannabis is a versatile plant as it can grow in almost all kinds of environments. As long as you provide the best growing environment, the right kind of cannabis nutrients, and good soil, it’s a guarantee that you’ll be growing healthy, high-yielding cannabis plants. However, there are times when cannabis plants suffer from nutrient deficiencies. We will discuss one of the most common deficiencies, cannabis phosphorus deficiency, and how to treat deficiency problems.
What is a phosphorus deficiency cannabis?
During the vegetative stage, cannabis plants require a completely different set of nutrients to grow healthy and strong. At this stage, cannabis plants need more nitrogen and less phosphorus and potassium. Nitrogen is important for growing new plant parts like leaves and stems while phosphorus and potassium are nutrients needed for large and dense buds.
When cannabis plants get less phosphorus, problems start to show on the plants’ leaves especially on the lower and older leaves. The lower leaves usually turn yellow or dark green and afterward, develop spots or large blotches. These large spots are brown or sometimes bronze with a bit of blue as well. The leaves of plants with low potassium levels will start to grow very thick and curl at the tips. In some plants, low phosphorus levels turn purple and red.
Most phosphorus deficiency goes with calcium deficiency as the two nutrients directly interact with each other in plants.
Common signs and symptoms of phosphorus deficiency
You will find the following signs and symptoms in cannabis plants with phosphorus deficiency
- Leaf changes that are present in the lower or older leaves.
- Stem color changes also happen as the stems turn red. However, this is not present in all plants with this deficiency.
- Leaves may turn dark and have a shiny texture. The dark color may be blue, green, or gray.
- Leaves may also turn yellow in different places especially if the deficiency is not treated. Yellow leaves may also be present in other nutrient deficiencies as well as other pH conditions. But when yellowing of the leaves happens during the earlier parts of the deficiency, this is not phosphorus deficiency.
- The leaves can turn purple, brown to bronze. There are also spots and blotches present all over the leaves.
- The leaves may start to thicken and may also become very dry and stiff.
- Sometimes, the stems become purple, red, and other bright colors.
- Phosphorus deficiency is common when buds start to grow and form. When phosphorus deficiency happens during the vegetative stage, the problem starts at the bottom part of the plant on the oldest leaves. If this is left untreated, the problem may move up.
What happens if you overlook phosphorus deficiency?
Cannabis phosphorus deficiency is very common in plants that are at the blooming stage as cannabis plants need phosphorus in the budding stage. This deficiency is unlikely to happen if growers use regular nutrients that are developed for cannabis plants. All nutrients needed during the flowering stage have high phosphorus levels. Therefore, if you have phosphorus deficiency while using regular nutrients, your plants may have problems deep within the root area.
Phosphorus is needed by cannabis plants from the vegetative to the flowering stage. It is represented by its element symbol, P, and is listed as one of the three very important nutrients.
What to do with cannabis phosphorus deficiency problems?
Now that you know what phosphorus deficiency is and the most common signs of this problem, it’s time to learn what to do in case this problem arises.
Correct pH
As soon as you notice phosphorus deficiency, check your root and soil pH. Plant roots and soil must have an average pH at 6.6 so, anything higher or lower is going to cause a lot of problems with your plants especially phosphorus problems.
Phosphorus is absorbed correctly when the root pH is 6.2 to 7.0 and when you’re growing in hydroponics, the roots must be 5.5 to 6.2. Any incorrect readily would mean that your plants’ roots are not able to absorb nutrients like phosphorus. The first thing to do is to flush your system with good pH-average water. After your plants recover, give them the right cannabis nutrients with the correct amounts of phosphorus.
Make sure that your plants have healthy roots
As you may have known by now, your plants’ roots play a huge role in ensuring good health. Aside from making sure that the roots have the correct pH, you must also make sure that your plants are watered the correct way. Never overwater as this can trigger all kinds of deficiencies including phosphorus deficiency. Water only when your plants are dry and high and not when the soil is still wet or moist.
You must also grow your plants in adequately-sized containers so the roots can grow healthy and strong. Overcrowding the roots will affect the way the roots absorb water and nutrients.
Ensure that your growing area has the correct temperature
When there’s an incorrect temperature in the growing area, your plants won’t be able to absorb nutrients like phosphorus better. Any temperature lower than 15 degrees Centigrade is also dangerous as it is unlikely your plants will survive. Cannabis seed a comfortable temperature to grow. If it’s too hot or too warm for you then your plants are hot and warm as well.
Provide the correct nutrients
Start providing correct nutrients after flushing. Use nutrients that are meant for the flowering phase or vegetative phase to avoid any nutrient problems. Take note that any excess of zinc and iron may also lead to phosphorus deficiency. So, make sure that your plants are getting the correct amounts of these nutrients as well. Just among the best sources of phosphorus are fish meal, crab meal, worm castings, bat guano, and bone meal or blood meal.
Lastly, monitor your plants’ recovery and take note of the soil and root pH daily. Create a diary of how to treat cannabis phosphorus deficiency in case you need to refer to this common nutrient condition in the future.