How To Fix Calcium Deficiency in Cannabis Plants

calcium deficiency weed
December 08, 2020

Macronutrients are essential trace elements, such as N-P-K, that cannabis plants seek out in large doses or amounts from the soil, as well as essential elements from air and water (hydrogen, oxygen, and carbon).

Micronutrients are trace elements, such as boron, copper, calcium, and more, which cannabis plants seek out in small doses or amounts from the soil. 

Micro and macronutrients work together through ionic bonds to create chemical compounds that transfer from the fluids found in soil to fluids within the root system during a process called osmosis

Once osmosis has occurred these micro and macronutrients are carried through a stream, the transpiration stream, where nutrients are directed throughout the plant for new growth, cellular development, or for treating a deficiency. 

The transpiration rate directly affects the rate at which transpiration happens. Transpiration is the loss of water from leaves by evaporation through the stomata. Transpiration then creates a tension, or a rope-like-pull, on the water molecules in the xylem vessels (narrow, hollow, dead tubes with lignin, responsible for the transportation of water and minerals within the plants’ system) by the leaves. Water molecules are cohesive so water is then pulled up through the plant, known as the transpiration stream.

The transpiration stream is beneficial to understand as well as what its purpose is within the cannabis plant. Let’s take a look! 

  • Transportation of importation mineral ions
  • Providing water to cells in the plant to maintain swollen vacuole from water gain due to osmosis
  • Transporting and moving water to cells in leaves to assist or allow them to photosynthesize or for photosynthesis.
  • Keeping leaves at stable temperatures, or otherwise cooling them, through evaporation

Transpiration and osmosis are important and vital processes for your cannabis plants to be able to grow, develop, and thrive. 

What Can Cause Calcium Deficiency in Cannabis?

There are a few causes to calcium deficiency and some of those factors will be determined by your grow medium, overwatering, your line of nutrients, other deficiencies being present, as well as the PH levels of your grow mediums, runoff, or feeds. 

Grow mediums can absolutely determine whether or not your plant will have available calcium at all times, or just within short periods during feeding times. Depending on if you’re growing in soil, living soil, soilless, hydroponic, or aeroponic, you will have different circumstances for every single one. You will also want to think about feeding different types of calcium, whether its a liquid calcium carbonate (which this one is not as efficient as the rest so we don’t necessarily recommend offering a calcium carbonate to your girls as a go-to), calcium nitrate, calcium chloride, calcium gluconate, calcium acetate, magnesium nitrate, and magnesium carbonate, as well as several other forms. In each grow medium these different forms will work differently with the mediums and your plant’s root system, so when figuring out calcium deficiency cannabis shows symptoms of, it’s best to have 2 or more forms of calcium accessible for your girls! 

Overwatering generally is an issue for soil growers, however, you soilless, hydroponic, and aeroponic growers can suffocate your girls, essentially overwatering, by not giving enough air within your reservoirs! Now we won’t break down into the separate grow styles here, however, just know that overwatering in the soil can cause your grow medium to be flushed or rid of important trace elements that include calcium which your plant won’t be able to seek. Microbes take time to process and break down the nutrients you’re giving your plant to make them accessible to the roots to be able to uptake them.

If you constantly flush your soil with water the byproduct your plant accesses that the microbes give off will be flushed away, this basically starves your plant. She’ll be unable to access any of the nutrients that haven’t been broken down and you’ll have flushed away all her food. The same concept applies a little differently with lack of air in reservoirs, however, instead of starving, you’re suffocating your girl. This means she can’t properly consume nutrients efficiently and she will become susceptible to disease, infection, and over prolonged time death. 

Depending on the line of nutrients you’re using, you may have a low amount of accessible or available calcium for your girls to consume. Be sure to read up on your line to make sure if you need any excess calcium you’ll have it from the start! Most organic lines are heavy in different calcium variations which is why we love organics! Some nutrient lines you can check out for yourself that we recommend would be Bloom Yellow Bottles, Nectar of the Gods, Fox Farm line, General Hydroponics, Vegematrix, and Neptune’s Harvest. 

Calcium deficiency cannabis shows signs of may not just be due to lack of calcium, your grow medium, or even a PH imbalance, it could very well be attached to another deficiency. What do we mean by this? Well, cannabis can have various forms of deficiencies such as calcium, magnesium, phosphorus, potassium, or several others. When your plant shows signs of one deficiency generally a second one is attached along with it, like calcium deficiency generally comes along with magnesium deficiency as well. This is due to the way these elements ionically bond and how your plant consumes them.

If your plant is deficient in phosphorus particularly, it’s almost impossible for your plant to source any calcium as calcium heavily bonds with phosphorus and potassium. So making sure you have well-versed knowledge in nutrient deficiencies will be a very big help when cultivating cannabis. Be sure to check out our other articles on nutrient deficiencies! 

PH imbalances will cause your macro or micronutrients (trace elements your cannabis plants either needs in large doses, macro, or small doses, micro, that are essential to plant development or growth) be unable to bind together to create ionic compounds, which are essential for the osmosis process to happen. Without osmosis happening in the root system, no nutrients are being consumed which means the plant will have no food running through its transpiration stream. This means being out of proper PH ranges can affect your plants’ ability to uptake nutrients, therefore causing deficiencies such as a cannabis plant calcium deficiency!

How To Identify Calcium Deficiency Weed Shows Signs Of?

There are several key indicators your plant will give you if it’s deficient in calcium. Let’s take a look at some of these symptoms and what you can look for! 

  • Yellowing or fading from leaf edges
  • Yellowing or more serious necrotic spotting will begin to form
  • Necrosis or necrotic spots will begin to appear across the center and edges of the leaves affected 
  • Root development will weaken as well as the color will shift to a brownish tone, which allows them to become susceptible to diseases or infections such as root rot
  • Heat will cause more stress on your plant during calcium deficient times, you’ll see leaves curl upwards on the edges or completely downwards from heat stress
  • Cellular strength, development, and growth comes to a halt which will lead to hollow stems or branches, meaning they’ll become brittle or easily broken.
  • Flower development will become less dense, colorful, or trichome covered, as calcium deficiency directly affects calyx development. 
  • New growth becomes faded, curled, twisted, or will fall off and die
  • Yellowing or purpling to new growth stems can occur, however, this is a symptom of several other deficiencies so this will be the last one you want to check’

Yellowing, necrotic spots, purple stems, and several others can be singular symptoms to other deficiencies as well, so it’s always best when diagnosing your plant to make a checklist of all of her symptoms and figure out which deficiency she fits into most. From that point, you’d work your way down the list of deficiencies that could be next if your first initial guess was wrong. Remember PH imbalances cause many deficiencies so always check runoff or reservoir ranges before adding amendments! 

What Does Calcium Do For Cannabis Plants?

Calcium plays a vital role in cannabis plants cell wall growth or development within the plant’s root system. As well as, enhancing the decomposition process of organic matter, which helps by assisting nutrient uptake. Calcium also acts as a bridge between humus, organic material that forms in soil when plant and animal matter decay, and nutrients. 

Calcium acts as a support to other elements that, when they bind, work together in different metabolic processes like creating vitamins, such as vitamin B12. 

Vitamin B provides various forms of stress relief, disease protection, bud development, and much more. Vitamin B comes in various forms and many growers utilize the various forms to help their cannabis plants develop healthily from seed to harvest. 

So all in all, calcium is a building block to a healthy, successful, strong, and fruitful (we mean big yields) harvest! Calcium plays key roles within the roots, stems, and branches, as well as leaves. So every part of your plant will suffer without this micronutrient. Be sure to have your favorite forms of calcium amendments on hand at all times! Just because one cannabis plant only ate a certain amount does not mean the next won’t want twice as much! Every plant is completely different and will require a different dosage or timing of feeds, not to say you can’t relatively feed your ladies the same compost, it’s just some plants may want more! 

How To Treat Calcium Deficiency in Soil?

If you’re a grower and you’re growing in soil or living soil there are a few different reasons you may see a calcium deficiency, aside from one being linked to another deficiency. For a problem linked to another deficiency you’ll need to diagnose the root cause first and foremost, then your calcium issue should fix itself or you may need to amend a little extra in your next feeding. Now for the actual true calcium deficiencies that pop up in soil, we have several options based on the situations, so let’s break it down! 

First and foremost you’ll want to always check your soil PH or the runoff PH, we check the runoff. If you’re not within the 5.6 to 6.5 PH range you most likely are facing a PH imbalance. To fix this, it just takes some time and patience. Simply feed your plants water PHed at 5.6 several days in a row, we recommend 3 days or until the runoff reads 5.6 to 6.5 PH range. Once you’re within the PH range that is best for your phase of growth, be sure to give your plant an adjusted feeding increasing calcium. You can use a liquid calcium amendment such as Nectar of the Gods Herculean Harvest or General Hydroponics Cal/Mag. There are also powder options such as Hi-Yield’s Bone Meal. Top feeds will be a slow-release back into your soil so be sure to give a liquid feed if you’re wanting to treat your deficiency as soon as possible. Proper PH ranges for your girls should be as followed below! 

  • Seedling to Mid Vegetative Stage – 5.6 to 5.8 PH range
  • Mid Veg to Flower Swap or Signs of Flower – 5.9 to 6.1 PH range
  • Flower to Harvest – 6.1 to 6.3 PH range and as close to 6.3 as possible

If your runoff shows that you’re within your ranges you may want to check how often you’re watering your plants. You may be overwatering. Overwatering can cause nutrients, that become accessible after microbes have broken them down, to be flushed away, which causes your plant to be unable to seek out those accessible nutrients. Essentially overwatering can starve your plant. We recommend following this general rule for watering. Offer water feedings every 3 to 5 days and every other watering changes to a nutrient feed. This way you allow your soil to dry out within that 3 to 5 day break period, as well as, allow microbes to break down nutrients for your plants to access. This keeps you from overfeeding as well as overwatering. Solves toxicity issues and calcium deficiency weed has issues with! 

If you’re figuring out how to fix calcium deficiency in plants while you’re within proper PH ranges, as well as you haven’t been overwatering, and you’re in or past the middle vegetative stage, then you most likely need to amend more calcium into your feeding. There are a few ways we can do this. Take a look below.

  • If you’re using compost teas to feed you can add a liquid calcium supplement such as General Hydroponics Cal/Mag which has calcium and magnesium within it. This will allow your girl to assist any magnesium deficiency which has latched onto your calcium deficiency, as magnesium tends to be the partner-in-crime to calcium deficiencies one could say. Now another option is adding bone meal powder. Nectar of the Gods has a bone meal in a liquid form named Herculean Harvest, and for dry form, Hi-Yield Blood Meal works amazing.
  • If you don’t use compost teas and feed using singular gallon water feedings, add a liquid calcium amendment to your water supplement for any fast-acting results. Any of the supplements above work well. For slow release and putting calcium back into your soil add a top feeding of bone meal powder, such as the Hi-Yield brand, to allow your girl to have access to calcium in the coming days or weeks! 
  • If your soil is not as nutrient heavy in calcium or additional trace elements add organic earthworm castings (iron, sulfur, calcium, nitrogen, phosphorus, and potassium) blood meal (N-P-K), and bone meal (calcium, iron, magnesium, copper, and zinc),  to your topsoil to give a plentiful supply of slow-release N-P-K-Ca-Mg, or nitrogen, phosphorus, potassium, calcium, and magnesium. This will give your soil the entire macro and micronutrients your cannabis plant will crave. Bone meals will be the highest source of calcium for your soil top feeds. So if your soil only needs calcium simply amend a bone meal to the top! 

You can also purchase a foliar spray like Bloom Yellow Bottle Groigen which has calcium within its amendments and will allow your plant to absorb calcium through leaf-zone-effect only. This way you can spray affected leaves and treat that area specifically along with giving your girl some calcium within her soil or grow medium! 

How To Treat Calcium Deficiency in Soilless, Hydroponics, or Aeroponics? 

If you’re growing in soilless, hydroponic, or aeroponic setups fixing calcium deficiencies marijuana shows symptoms of will be a much quicker fix than in soil. Generally, this principle goes for most deficiencies as soilless, hydroponic, or aeroponic systems the roots are directly affected, shocked, or treated since there isn’t a buffer like in soil or living soils.

So in soilless, hydroponic, or aeroponic setups, there are a few ways you could see calcium deficiencies, and the most common one being PH imbalance. If you’re out of ranges in these types of grow mediums the shock to the plant is much more drastic. Having a stable reservoir or reservoirs will be key to maintaining healthy and deficient free plants. We always recommend going with larger reservoirs if you plan on growing in these setups, a 25-gallon reservoir or higher will create a more stable PH range, PPM range, and temperature ranges. This will promote the best uptake of nutrients as your PH ranges won’t be shifting so drastically. If you’re out of PH range you have two options that we recommend, which are natural acids or liquid PH adjusters. For natural acids, you have potassium hydroxide for PH up and phosphoric acid for PH down. These are very serious and potentially dangerous chemicals so please use caution if you plan on working with natural acids. Keep in mind as well, these natural acids contain large trace amounts of potassium and phosphorus so you may not need any additional P-K in your regimen. Now if you don’t have access or don’t wish to work with natural acids you can use liquid PH adjusters that are just as natural, but they’re way more fast-acting, concentrated, and you don’t end up with additional trace elements. We recommend Nectar of the Gods PH up or Down as well as General Hydroponics PH up or Down! There are many great brands out there however we’ll stick to some of the more widely used in the community. Check out the proper PH ranges we recommend below for soilless, hydroponic, or aeroponic setups! 

  • Seedling to Middle of Vegetative Stage – 5.5 to 5.8 PH range
  • Mid Veg to Flower Swap – 5.9 to 6.1 PH range
  • Flower to Harvest – 6.1 to 6.3 PH range and as close to 6.3 as possible

If PH isn’t your problem as you’re within the ranges we recommend above then suffocation or overwatering essentially, could be your problem. If you are growing in soilless, hydroponic, or aeroponic setups it will be vital to have as much oxygenation as possible within your reservoirs. In soil or living soil grow mediums, perlite, peat moss, sphagnum moss, and other aery or aerated substrates give the soil room to breathe or access to fresh oxygen.

In soilless, hydroponic, or aeroponic setups you’re directly responsible for supplying the root system with its oxygen. If you do not have enough oxygenation you essentially suffocate your plant otherwise drowning it. This will cause your girl to become droopy, fall over, show signs of deficiencies, and if left untreated, death. Proper air pumps and air stones are key to creating enough oxygenation within your reservoir to promote healthy growth! 

Now if PH isn’t your problem, overwatering or suffocation isn’t your problem, and other deficiencies aren’t your issue (if that’s your problem you’ll need to make a checklist of all your plants symptoms and diagnose the root cause, which your calcium deficiency should disappear or become treated once you fix the initial deficiency), then chances are you most likely just need additional calcium within your feeds. Soilless, hydroponic, and aeroponic nutrient lines generally are par-synthetic, solvent, or salt-based utilizing various forms of accessible nutrients. So with that being said many forms of soilless, hydroponic, or aeroponic nutrients will be able to give your girls instant access to calcium. So simply amend more calcium into your next feeding and you’ll notice that deficiency symptoms start to dissipate. Now if you’re using organics you can use calcium feeds such as liquid bone meals like Nectar of the Gods Herculean Harvest. This will allow your girl to access large amounts of calcium as well as other trace elements she’ll be happy to have!

Generally when using these grow mediums we recommend staying away from powder forms of any nutrients as it can clog your systems, however, if you have access to powder forms of calcium that work well in soilless, hydroponic, or aeroponic setups we recommend those as well!

Now, remember calcium, like any other deficiency, can and will be linked to other various deficiencies. It’s best when diagnosing your cannabis plant to make a full list of her symptoms before treating her with any forms of amendments, flushing, or corect PH. You wouldn’t want to make your problem worse by treating the wrong problem!