How To Identify & Fix Boron Deficiency In Cannabis Plants
Boron is a primary micronutrient found in all plants. Its principal function is to help hold the structural integrity of the cell walls for your cannabis crop. Boron is present in soluble and insoluble states. Boron deficiency in cannabis happens when an insufficient amount of the nutrient exists in the plant.
The presence of boron in your cannabis garden is determined as the plants develop. Each crop takes up a fixed intake once they reach maturity; however, some may not get enough. You can spot symptoms of cannabis boron deficiency early on.
Worried you might be facing this issue? Read on. We'll discover what signs to look out for and how to deal with boron deficiency in cannabis. We also learn about boron toxicity and how to tackle the issue. Let’s get going.
What is boron deficiency in cannabis plants?
Boron deficiency is when your plants lack the nutrient, and you see their structural integrity compromised. The issue occurs commonly in dry climates, where there’s a lack of water and dry air.
Boron deficiency in cannabis plants can also happen when there are issues with the pH levels in the water and soil or a lack or excess of other nutrients. A few symptoms indicate boron deficiency, but it starts with brownish or yellow spots on your plants.
You'll notice other issues as well, such as uneven tips, twisted growth on the stems, and wrinkled and curled leaves—even if they're new. Boron deficiency in cannabis also affects the roots of your garden, with slow growth being the primary symptom.
Ultimately, boron deficiency in cannabis leads to other types of shortcomings since other nutrients use boron to keep the structure of the plant.
What does boron do for plants?
Why is a boron deficiency in cannabis so detrimental? As a micronutrient, boron is a key component of the cellular structure of your cannabis crops.
The mineral is redirected to all parts of the plants to help with cell wall formation and make the plants stable with solid structures. Boron also assists the crops with the function of all biological membranes while also keeping their integrity uncompromised. It also carries the energy required by the plant in the form of sugar to help them work as they should.
Boron sulfides aid the pollination process, and they also help with the creation of new seeds. The mineral prevents chlorosis by keeping your plants green. The minute you see your cannabis garden sprout dried tips and yellow leaves, it's time to consider using a boron supplement for plants.
What causes boron deficiency in weed plants?
Boron deficiency in cannabis can appear for many reasons. If you know how to identify the cause of this issue, you can take action promptly. The following are some of the most frequent causes of a B deficiency.
No boron presence in the fertilizer formula or the water
You can buy the best cannabis nutrients available, but it doesn't do much if you don't feed your crops properly. Ensure your plant is getting enough boron by ensuring the pH for the soil is at 6.5 to 7 after applying the water and nutrients.
Soil is too dry with no waterlogging properties
Planting marijuana seeds in dry or tightly packed soil is a great way to attract a boron deficiency in cannabis. Even if the cultivar can handle harsh conditions, the soil needs good waterlogging properties. Transfer crops to a better medium to solve the issue.
Too much humidity or wrong pH levels
We can cause issues by offering our plants too much of a good thing. Excessive humidity or the wrong pH level in the water we feed can create trouble. Make sure relative humidity (RH) levels are 40–50% during the flowering stage. The pH of the water needs to be at 5.5–6.5 before pouring it onto the roots.
Too much calcium
Calcium is essential to marijuana crops. However, exceeding amounts of it can cause many issues. Even the best boron supplement for plants can cause cannabis nutrient burn. If you overfeed the nutrient to your plants, you’ll see them affected by weak and hollow stems, also one of the symptoms of cannabis boron deficiency. Both nutes rely on each other to function properly, and when there’s too much of one, it affects the other.
Cold roots
When learning how to fix boron deficiency in plants, consider temperatures. The temperature of the water you use to irrigate the plants and that of the soil affects its growth. Low temps can cause cold roots, which means they can’t take up the boron needed for healthy development.
Boron deficiency symptoms in cannabis plants
Knowing what to look out for when it comes to lack of boron can help you act fast when a problem arises. It's important to notice the symptoms since they can also be signs of other issues. You're likely dealing with boron deficiency in cannabis plants if you notice any of the following:
Growth issues
Your cannabis plant growth is twisted and burnt, the foliage develops slowly, and leaves die off easily. You’ll notice your crops are stunted, with side shoots lacking strength and curling easily.
Development issues
New leaves turn yellow and brown quickly, with clustered thick tips. There’s no presence of trichomes since the plant is dealing with cellular weakness.
Structural issues
The plant looks limp and lackluster due to a significant slowdown in its metabolic functions. It also shows poor root growth, with many dying off. Weakened roots make the plants prone to bacterial infections, while their exterior goes brittle with hollow branches due to nutrient deficiencies.
How to fix cannabis boron deficiency?
A boron deficiency in cannabis can happen if you’re not careful, but you can fix cannabis deficiencies if you apply a prompt solution. We present some of them below:
Use nutrient packs
Boron deficiency in weed can sometimes be remedied quickly by investing in a good nutrient pack from your local garden center. They help you boost the growth of your plant by giving it more boron and other minerals it might be lacking. Water is already loaded with nutes, but the soil needs the extra help to achieve the best conditions for your crops to thrive.
Adjust the pH levels in the soil and the water you're using
You can fix boron deficiency in cannabis by adjusting to the right pH level in the water you feed your plants and the soil. We recommend buying a handy soil pH meter to get the right reading.
Whether you choose pots or sow your seeds outdoors in your garden, the soil needs a 6.0–7.0 pH level—the best absorption rate is at 6.5. When it comes to water, the best pH for cannabis plants is around 5.5–6.5, with boron intake better provided at 6.2.
Keep good moisture levels
Boron doesn’t absorb well without enough moisture. Most cannabis cultivars offer their best with relative humidity levels between 40–50%. If the air's humidity goes below 25%, you'll see deficiencies. Spray your plants daily to ensure there’s enough moisture.
Keep an eye on the leaves for recovery
After taking measures to deal with the symptoms of cannabis boron deficiency, watch out for recovery signs. The most apparent indicator is the leaves. Any old damaged growth won't improve and needs to be pruned, but new leaves should show signs of renewed life.
If you’ve used a nutrient mix with nitrogen and potassium and water them regularly, you'll see improvement within two weeks. Your choice of setup plays a considerable role as well. Controlled environments benefit a ton from additional measures such as humidifiers and controlled lighting.
Below is a summary table highlighting certain boron deficiencies in cannabis and how to remedy them.
| Deficiency | Solution |
| Lack of minerals | Use a nutrient pack |
| Bad readings in soil and water pH | Use tap water and a pH meter on both |
| Lack of moisture | Use a water sprayer on top of daily irrigation |
What is boron toxicity in cannabis?
Boron toxicity happens when your cannabis plants have the nutrient in excess. It's the opposite of boron deficiency in marijuana. The most common evidence of toxicity is the nutrient burn showcased on the leaves. Some gardeners refer to these as necrotic lesions since the affected foliage can't recover from them.
You'll also notice how these leaves suffer from premature aging and shed. The toxicity affects the whole plant. The roots, in particular, can suffer from stunted growth or damage. You can find localized chlorosis in some rare stances, but it's more an exception than the rule.
For some gardeners, it can be hard to differentiate boron deficiency in cannabis from toxicity. The main difference is that boron toxicity is outlined in black around the affected areas on leaves, next to the brownish or yellow spots. Deficiencies tend to make them look dry.
How to treat cannabis boron toxicity?
Fixing boron toxicity isn’t as complex as remedying boron deficiency in cannabis. Here are some of the steps you need to take:
- Dry your plants: Your garden may be suffering from boron toxicity because you fed it too much water. Make sure to cut water consumption to half of what you're giving daily and provide the plants plenty of sunlight.
- Flush your cannabis plants: This process removes nutrient leftovers and cleanses the soil. It also gives your plants a clean slate to let them absorb new nutrients more effectively.
- Use pH-balanced water: The best pH level for water should always be between 5.5 and 6.5. Make sure to measure it before administering it to your plants.
- Adjust the pH levels of the soil: If you're working with soil, the pH level should be between 6.0 and 7.0. Using a nutrient pack or natural soil balancing elements, such as coco noir, lime, dolomite, or even poultry manure, can assist this process.
Get rid of boron deficiency for good
Growing marijuana isn’t complicated, but we sometimes have to deal with issues, such as boron deficiency in cannabis plants. It's a problem that puts your garden at risk, but you can solve it with some attention to detail and plenty of care. Make sure the soil and water your plants get are optimal and have the right pH levels.
A boron deficiency in weed can cause as much trouble as too much, so keep an eye out for lacking nutes and toxicity. If you have any more questions, head to our Homegrown Forum and ask as many as you need. Our Homegrown Cannabis website also boasts plenty of experts willing to answer your queries.
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About the author: Parker Curtis
Parker Curtis has around a decade of cannabis-growing experience, specialising in soil-less and hydro grows. He’s mastering outdoor, greenhouse, and indoor grows.