Is it common for marijuana plants?
In the outdoor growing of cannabis Calcium (Ca) deficiency is rare. Except in soils that are very acidic. Sometimes this deficiency is found in planting mixes, but mostly it is found in hydroponics. This deficiency sometimes occurs in soil-less growing mediums. Mostly when the mediums we’re not supplemented with lime. Lime mostly exists of calcium.
Some types of water lack an expressive amount of dissolved calcium. Like distilled osmosis water, reverse osmosis water and even some types of tap water. If the water is not supplemented with calcium, it can cause calcium deficiency to your marijuana plant
The growth of the marijuana plant is stunted by the calcium deficiency and the leaves become dark green. Dried tissue and large necrotic blotches of tan are the results. You will find this mainly on new growth. But it can also occur on other parts of the marijuana plant (near leaf edges). A purple or yellow color will occur on the young shoots and the shoots will crinkle. In the worst cases the shoots will twist before they die. Along the lateral leaf margins necrosis appears. These problems move to the older growth. The older growth browns and dies. Branches and stems of your cannabis plant crack easily, lack flexibility and are weak.
The root system doesn’t properly work. This leads to bacterial problems. The bacterial problems cause root disease and the roots die-off. The roots of your marijuana plant suffer from discoloration and become sickly brown.
Calcium is found to be semi-mobile.
Role in plant nutrition
Marijuana plant cell walls are strengthened by calcium. Thus it strengthens stalks, branches and stems. Calcium helps the growth of root, mostly in the newer root hairs. Calcium tends to concentrate in older growth and roots. Calcium travels slowly. The uptake of K is enhanced by calcium.
Solving the problem
To solve calcium deficiency to your marijuana plants use garden lime or Dolomitic lime. Add the lime before potting into the planting mixes. The lime helps stabilize the pH level over a certain amount of time. The lime also provides calcium.
Hydro cannabis growing systems, but also planting mediums, can be fertilized by using a commercial calcium-magnesium formula. This formula provides instant availabilities. Also, this formula can be used in the planting mixes. Most marijuana growers use calcium-magnesium acetate or calcium acetate.
If you need water soluble fertilizer that delivers both nitrogen and calcium to your marijuana plant, use Calcium nitrate (CaNO3). This supplies calcium in a very soluble form to the roots. CaNO3 is also used as a foliar spray. CaNO3 is very quick in providing the cannabis plant with calcium. During the flowering stage CaNO3 must not be added. CaNO3 also supplies excess nitrogen and this is unwanted in the flowering stage. There are several brand of liquid lime or liquid calcium available. The roots of the marijuana plant absorb this quickly.
A relatively fast absorption is provided by one teaspoon of hydrated lime per gallon of water. You can also use Dolomitic limestone. This contains calcium and magnesium. The use of this Dolomitic limestone will take longer to absorb. This is a good way to prevent deficiency, use it by placing it in planting mixes.
When growing cannabis outdoors, adjust the pH range to 5.9-6.5 and add calcium to acidic soils. You should use garden lime or Dolomitic lime. You can also use fish bones, seashells or egg shells. These break down over the season and calcium is added to the soil.
You can add calcium sulfate (CaSO4), gypsum, to outdoor soils. In this way you increase the calcium content without affecting the pH level too much. Do not add it to soils with a pH level lower than 5.5. Otherwise it will make it poisonous and soluble to the marijuana plants, because it interacts with Aluminum (Al).
Discussion in general
All most all planting mediums contain an adequate amount of calcium. But if the pH level of your planting mix is too low, add calcium.
Marijuana plants in hydroponic systems are the most likely to suffer from deficiency in calcium. There are some hydro fertilizers that only have little amount of calcium. The amount of calcium dissolved in the water varies. The water probably provides the cannabis plant with enough calcium if the water contains more than 150 parts per million (ppm) dissolved solids. Calcium-magnesium must be added to the water if the water contains less than 150 ppm of dissolved solids. If you want to know how hard or how soft your water is you can use a tds/ppm meter. Also you can refer to the quality report of the local water district.