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Boron Deficiency - Cannabis Plant Problems

How to Fix Boron Deficiency in Cannabis Plants

Modern cannabis nutrients often perform well. Though if things go wrong and plants look sick, boron deficiency may be the culprit to blame.

Boron is a plant-essential nutrient though safe and unsafe levels of it in crops do exist. Cannabis plants, like humans, require minerals and nutrients to thrive and properly develop.

Cannabis plants are no exception as they rely on micro-nutrients, such as boron, to grow and finish lifecycles, and if they get the right amount of this nutrient they will produce optimal yields for growers.


Learn more about boron deficiencies below along with how to fix the problem

Why is Boron Important for Growing Cannabis?

The element boron is a nutrient that helps plants to grow and develop. However, cannabis plants need only small amounts of it, and if they receive too much or not enough of this vital element they can suffer from root or lead necrosis, or nutrient burn as referred to by most growers. As such, with boron, there is a sweet spot in which fertility is optimal and not toxically over-applied.

Fixing boron deficiency in cannabis plants will give crops the nutrients needed to produce quality buds, and when the plant receives its essential minerals, speeds up flowering and harvest times for growers.

The first step to resolving malnutrition is to learn the signs of boron deficiency. Boron helps cannabis plants absorb other nutrients, such as potassium and calcium, and if not receiving enough can develop a range of symptoms no grower wants to encounter. Though fortunately, there are ways to spot and treat nutrient deficiency in cannabis plants, and below we will show you the ways.

boron cannabis

How to Identify Boron Deficiency in Cannabis Plants

As an essential micronutrient, boron fortifies the structural integrity of cell walls, promotes the health of metabolic pathways, and supports plasma membranes, which help plants to thrive and grow their best.

Insoluble boron plays a large role in plant health though is the culprit of most overdoses, however, plant cells rely on insoluble boron which they source from the soluble variant. Boron deficiency occurs during early lifecycles though is resolved once absorbed by the plant. Calcium, nitrogen, and other essential nutrients work in harmony to ensure plant health, though if boron levels are low, even if other nutrients are not, plants can show a range of deficiency signs.

what does a boron deficiency look like

For example, grey or brown spots similar to those caused by calcium deficiency may show though ones caused by a lack of boron appear larger. Purple stems may be a sign of coldness or nitrogen toxicity but could be boron deficiency too, although, stems on boron-deficient plants are softer to the touch so it is easy to tell which deficiency the plant is struggling with.

Boron deficiency can drastically impact harvest quality and may:

  • Cause plants to lose their lushness due to turgor pressure which forces the plasma membrane against the cell wall. This is a common cause of baron deficiency and easily noticed on cannabis plants which so often are admired for their vibrant growth.
  • Reduce the plant's fertility and production of pollen which encourages sterility. Calyxes often underdevelop and modified leaves, known as bracts, will display signs such as brown dead spots.
  • Affect vegetative and reproductive growth and impact all other stages of its lifecycle. Boron deficiency can slow growth and vegetation cycles and inhibits the production of flowers too.
  • Kill meristems which are plant tissues containing cells needed by plants to properly grow.

stages of boron deficiency

Boron deficiency is relatively rare and usually occurs when plants in dry environments are inadequately watered. This is often accompanied by other nutrient and pH issues and reflects in the color of leaves.

The first sign of boron deficiency is thick-growth tips and brown or yellow-spotted leaves. Leaves atop the canopy may slowly or abnormally grow and may exhibit twisted growth or even die.

Stems and leaves alone are not affected as plant roots are too. Stems may be soft or rough, and hollow as well and usually occurs when plants in low-humidity environments are under-watered.


Boron Deficiency Symptoms on Cannabis Plants

Plants with not enough of the nutrient may look calcium-deficient as boron is needed for plants to use calcium. Boron deficiencies mimic calcium ones as both rely on each other to maintain healthy plants.

New plant growth is affected most and may look burnt or scorched. Since nitrogen and potassium are needed for plants to use boron, those with discolored leaves may struggle with boron deficiency and not a shortage of potassium or nitrogen.

One sign of boron deficiency is new vegetative growth that is either twisted or burnt. This growth eventually dies, falls from the plant, and topples it.

New growth is usually thick and clustered instead of wide and tall and often has vividly-green leaf tips. Sugar leaves will no longer reach for light as boron is essential for cell strength, a deficiency of it means plants overtime will droop and collapse as they no longer have the strength to reach for its light source.

Branches and leaf stems of boron-deficient plants can turn soft and purple while becoming hollow too. This is due to metabolic functions of the plant being interrupted, which causes the whole plant to suffer. Main roots die and then secondary ones swell which makes them susceptible to bacterial infections. Dried tissue begins forming around small brown spots across leaves that soon crumble away to lie around stems that, since becoming boron-deficient, became rough, brittle, and internally hollow.


In the unlikely event a plant becomes boron deficient, growers can:

  • Apply a mix of four liters of water with one teaspoon of boric acid to plants, results are speedy.
  • Once recovered, rinse plants with water or marijuana tonic to begin normal nutrient regiments.
Most tap water contains boron so growers using highly-filtered water to feed plants are most at risk.
As with all deficiencies, growers should test the basics first by checking the pH and ppm/EC of water and the dissolved solids found within it.

example of boron deficiency on cannabis leaf

Solutions for Boron Deficiency in Cannabis Plants

At times, cannabis boron deficiency resolves itself. If stressful conditions rather than environmental ones cause malnutrition it will likely recover on its own if moved to a more suitable environment or when changes to its current one are made.

Thankfully, if deficiency-induced malnutrition occurs, there are ways growers can revive and save plants.

Let’s review the best ways to combat cannabis deficiency.


Using Good Sources of Nutrients

Most growers do not need to add more nutrients. In fact, most have already given their plants enough boron, whether intended or not.

With quality, cannabis-friendly soil, more boron is likely not needed. Boron deficiencies usually occur when growers are giving their plants water with the wrong pH level, or using highly-filtered or reverse-osmosis water to feed plants as such water has been stripped of the element.

So long as plants have a good water and nutrient source with the correct pH level, boron deficiency should never occur.

good nutrients

Adjust pH Levels to Correct Range

Most growers encounter cannabis deficiencies as plants best absorb B from low pH ranges. When pH levels are too high, plants can show signs of boron deficiency, especially near roots.

In soil, roots absorb boron best in the 6.0-6.5 range. While it is recommended this range be between six and seven, boron is best absorbed under 6.5.

In hydroponic grow spaces, a pH of 5.5-6.2 is best for roots to absorb boron. Most suggest the range to be 5.5-6.5 but boron absorbs best under 6.2.

adjusting ph levels

Provide Plants Enough Moisture

Plants do not absorb boron well when moisture is low, this may occur when humidity is below twenty-five percent or when plants are under-watered. Properly watering cannabis plants can prevent this, and if humidity is problematic can be resolved using a humidifier.


Monitor Leaf Recovery

If a plant is suspected of being boron deficient, flushing the plant with pH-balanced water is best as it contains cannabis-friendly nutrients the crop needs to thrive. Discolored, aged, and dying growth are unlikely to recover and is often pruned by growers as part of the process. Growers should closely watch inspect plants for a few days to see if new growth or additional signs of deficiency emerge.


Boron Deficiency and Cannabis

Boron is a vitally important nutrient helping cannabis plants to use calcium. Plus, it also helps with pollen germination, cell division, maturation, and protein formulation.

This nutrient also helps plants to grow strong and healthy and to develop colors at their full potential.

When plants lack boron they often contract boron deficiency but is unknown to growers until symptoms show. That said, prevention is better than treatment, it is better to prevent a fire than to put one out.

Meaning, it is essential only pH-balanced water and nutrient-rich soil are used as this provides boron to plants and also other nutrients such as potassium and calcium as well.


Signs of Boron Deficiency

At times, this condition is confused for calcium deficiency as both show resembling signs early on.
Growers can determine the root cause by watching for signs that include:

  • New lead growth is affected first.
  • Pale green or yellow leaves.
  • Stunted growth.
  • Leaf tips are thicker than normal.
  • New shoots are twisted or burnt.
  • Leaf tips begin having burnt tips.
  • Dark brown spots between veins.
  • Leaves become thick and brittle.
  • Stem growth becomes twisted.
  • Rust-colored stems develop.
  • Leaves turn purple or dark green.

boron deficiency symptoms

Final Thoughts on Cannabis Boron Deficiency

With knowing the signs of a boron-deficient plant, growers can swiftly resolve malnutrition and revitalize the crop to its former glory.

We here at StickySeeds appreciate you and the many other visitors entrusting in our brand to deliver guides and industry news on the subjects mattering most to our audience.

Serving thousands of cannabis enthusiasts each month, users can buy cannabis seeds and access cannabis blog posts that are updated weekly.

We hope you learned how boron deficiency in cannabis plants are identified and treated by growers, by using proper water and soil along with preventative steps as shared above, preventing this issue is easier and will make harvests easier to sustain and more enjoyable to cultivate.



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