Boron deficiency in marijuana plants
Boron deficiency is a significant issue, as boron is a crucial nutrient that helps plants absorb and utilize calcium efficiently. This deficiency can have multiple causes, and it’s essential to correct it promptly to prevent more serious complications in plant growth and development. Find out here in our guide how to spot and correct boron deficiency.
What is boron in the crop?
Boron is a trace element nutrient for plants. Boron helps with ripening, germination, pollen viability, seed production, cell division, protein formulation, keeping leaves a healthy colour, and the formation of plant structure. It also maintains the stems, stalks and branches of the plant at a healthy level of strength.
What are the consequences of boron deficiency?
When there is not enough boron or your plant has restricted access to it, chances are it has a boron deficiency. It is rare that a boron deficiency is the only problem your cannabis plant has if you notice it has this condition. It can come from an unbalanced pH level and can come with other nutritional problems.
Causes of Boron Deficiency
- Inadequate pH: High soil pH can prevent boron uptake by roots.
- Soils poor in organic matter: Soils without sufficient organic matter tend to have less available boron.
- Excessive irrigation: Continuous irrigation can wash out available boron, reducing its concentration in the soil.
Signs of a Boron Deficiency
You will start to notice that the upper leaves of your marijuana plants grow abnormally or more slowly than normal. The tips of the buds will not grow well, i.e. they may appear twisted and start to die prematurely. New leaves may be wrinkled or curled upwards.
Boron deficiency is more common in western soils, although even in western soils it is quite rare. This means that it is not the most common nutrient deficiency. Boron deficiency is also non-motile, which means that it will only affect new growth.
When there is a boron deficiency, the roots of your plants will grow unhealthily or slowly. Stems, including those of the leaves and main stem, may begin to hollow and become rough. Deficiencies of this micronutrient, boron, are more likely to occur when the plant has not received enough water or when air humidity is extremely low.
As boron helps plants to assimilate calcium, the symptoms may appear similar to those of calcium deficiencies. Also, often, a boron deficiency also comes with a lack of potassium or nitrogen, as a plant requires these nutrients in order to use boron.
Difference between Boron Deficiency and Other Problems
Boron deficiency mainly affects the growing points and causes deformation of young leaves. Unlike magnesium, which affects the older leaves, boron deficiency manifests itself in the young leaves. In addition, calcium, although it also affects young leaves, does not cause deformation.
How to Differentiate Boron Deficiency from other Deficiencies
- Stunted growth: Growing points may die from lack of boron.
- Deformation of young leaves: New leaves become deformed or brittle.
- Comparison with calcium: Calcium affects young growth, but does not deform leaves.
- Affects flowers: Boron deficiency can cause malformation or delayed flower development.
- Difference with magnesium: Magnesium affects old leaves first, while boron affects young leaves.
When the growing tips of the marijuana plant start to look brown or grey and eventually die, it is safe to assume that a boron deficiency is the reason. After these tips die, they will begin to grow, but without enough boron this growth will soon lead to death. Before dying, these shoots will appear sunburnt and gnarled, and will have a deep green colour.
The leaves will start to develop brown spots and begin to drop dead, and the surrounding tissue will clearly also die. These spots are the way to distinguish boron deficiency from calcium deficiency: the spots are smaller with the boron problem.
If a boron deficiency is left untreated, it will eventually stop root growth, and cause secondary roots to shorten and swell. Because the roots are more fragile in this state, there is an added risk of fungal or bacterial infections. Unless stopped, boron deficiency will cause all the leaves on the plant to fall off, and the plant itself will eventually die.
List of Symptoms of Boron Deficiency in Marijuana
- Pale leaf colour
- Purple colour or darkening of leaves
- Dark brown spots on leaves
- Brown or burnt leaf edges
- Thicker growing tips
- Slow growth
- Twisted or abnormal growth
How to correct a Boron Deficiency
Most of the time a boron deficiency comes from the grower overfeeding their plants. Make sure you avoid this so you don’t end up with a boron deficiency in the first place. You could use something like a marijuana booster from the start to avoid a boron problem.
Most cannabis growers do not need to add more nutrients. In fact, most growers have already given plenty of boron to their cannabis plants, whether they wanted to or not. If you are using quality soil or cannabis-friendly nutrients, you probably don’t need to worry about adding more boron.
Boron deficiencies are generally more likely to occur when a grower uses heavily filtered or reverse osmosis (RO) water to feed plants. This is because boron is found in most tap water, but that is not the most common reason growers see boron deficiencies in their cannabis plants.
If you find yourself with boron deficient plants, you have a few treatment options. You can treat your water solution with boric acid: one teaspoon of boric acid per 5 litres of water. You can use both compost and compost tea to treat this problem.
Boron deficiency and pH
But the reason most growers see boron deficiencies is that boron is better absorbed with lower pH ranges. When the pH gets too high, the plant can show signs of boron deficiency, even if it is physically close to the roots.
Boron deficiency is sometimes caused by the pH level being too high or too low. In soil, the roots can absorb boron best if the pH level is between 6.0 and 6.5. In a hydroponic system, boron uptake occurs best between 5.5 and 6.2. It is also important to flush the entire system with water at the right pH, as well as with the mixed nutrients. You should see new growth start to come in normally within a few days. Check out the links below to find out more about pH and EC.
Boron deficiency due to lack of nutrients
A boron deficiency can also be due to a lack of potassium and nitrogen, in which case you should water the plants regularly with these nutrients. If your grow room is quite dry, you can use a humidifier to help reduce the symptoms of boron deficiency.
Boron is not absorbed well if there is not enough humidity, for example if the plant is under water or the humidity is very low (below 25% relative humidity in the air). Proper watering practices will help to avoid underwatering, and a humidifier may be needed to achieve the best growth if the grow room is very dry. You can also apply a boron-rich fertiliser.
If you suspect your growing cannabis plant has a boron deficiency, flush your system with clean, pH-rated water containing a regular dose of cannabis-friendly nutrients. Damaged old growth is unlikely to recover. Keep an eye on the plant over the next few days to make sure the problem stops spreading to new growth.
Boron is found in most tap water, so unless you are using extremely filtered or reverse osmosis water, you should not encounter a boron problem. If you are watering your plants with tap water and they appear to have a boron deficiency, first check conditions with similar symptoms to see if boron is really the problem.
Remember that plants with strong genetics are less likely to get sick. Make sure you buy cannabis seeds from a reputable seed bank.
Not sure if your plants have a boron deficiency? get ready for the monographs on Cannabis deficiencies:
Iron deficiency
Magnesium deficiency
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Founder of Experiencia Natural, creative and entrepreneur, designer, master in grower and marketing. For a normalization of all plants and substances, giving priority to patients and users.
