Spraying plantsCalmag for plants is a supplement feed that is highly recommended for better growth, healthy blooms, and yield. If you are looking to give your plants the optimum nourishment and improve their foliage and health then this article is a must-read.

Our experts list out the most important information that you need to know about the supplement and how it can have a positive impact on your plant.

Read on and learn how to use cal mag as well as how you can make your own supplement of the same at home. 

What Is Calmag for Plants?

Cal-mag is a liquid supplement that gives plants the essential micronutrients of calcium, magnesium, and iron. These much-needed elements are vital for plants to produce blooms, fruits, and high yields.

A shortcoming or deficiency of these nutrients can hamper health, growth, and even the plant’s look drastically. Moreover, it protects the plants in several ways by keeping them away from bacterial and fungal infections.

Should You Give You Plants Cal-mag?

Yes, you should give your plants cal-mag as it is important for optimal growth as mentioned in the above section. Calcium and magnesium come with many benefits and these are enough reasons for you to ensure your plant is never deprived of them. We have listed a few of the key benefits of these nutrients for the plant.

– Reasons Cal-mag Is Required 

  • Calcium and magnesium increase the pH of the growth medium whether it is soil or water. Additionally, it aids to maintain the right level.
  • Calcium helps new cells to build, thus promoting plant health. A lack of it will lead to stunted growth or inadequate blooms and smaller fruits and vegetables.
  • Magnesium aids in the production of chlorophyll and thus is an essential nutrient for the plant to trap the sun’s energy. A deficiency of it will result in shorter stems that will bear a limp and wilted.
  • It also protects the plant against fungal and bacterial diseases, as stronger cell walls make it difficult for microbes to penetrate through.

– Water The Plants With Soft Water

If you have been watering your plants with soft water you are bound to have a deficiency as soft water has a lower pH and minimal minerals in comparison to hard water. Therefore, if you are in a zone where you just have soft water available, you have to provide your plant with a cal-mag supplement.

Additionally, treated water to requires supplements as the distillation process tends to strip the water of these essential micronutrients. For hard water users, the high presence of calcium and magnesium takes care of the plant’s needs easily. 

What Does Cal-Mag Do for Plants?

Cal-Mag liquid supplement is designed to provide the plant with over-the-top nourishment, to reduce any damage caused due to deficiency of micronutrients. It improves overall plant health by preventing blossom rotting, greener foliage, and maximum yield sizes.

In hydroponic plants, cal-mag is beneficial as this system of irrigation relies on liquid nutrition. The supplement can easily be distributed across the channel through the reservoir that is connected to it. 

How To Identify a Deficiency?

You can identify a calmag deficiency in a plant with the help of some tell-tale signs. If you spot any one of the below-mentioned symptoms you can be assured that there is indeed a lack of nutrients and the plant requires some over-the-top feed.

– Slow or Stunted Growth

Do you find the stems of the plant stunted or short? Or is the plant not producing fresh leaves? This is a common sign that there is a deficiency and that the plant is struggling to thrive to its complete capacity and produce fresh foliage.

– Buds That Don’t Bloom

A deficiency will result in buds that don’t bloom or flowers that drop before they open up fully. You will also find fruits to be smaller in size or with localized rots on their surface.

– Darkened Foliage

Calcium deficiency in the plant will also result in darkened foliage. The leaves may sport yellow and brown spots and the tips turn brittle as well. 

– Root Rot

This is not a very obvious sign, but plants can develop root rot due to a deficiency. Under this condition, the leaves may look wilted and the roots may emit a foul odor.


How Do You Apply it to Plants?

Calmag can be applied directly to the plant medium whether it is grown via a hydroponic system, water, or soil. Here is how you go about it.

– Applying Directly on Plants

For plants grown in hydroponic systems, mix cal-mag in water, directly into the main reservoir of your hydroponic grow system. This will be distributed through the distribution feed lines to every pot or bucket connected to the system. Most importantly, remember to add calmag every time you change the water in the reservoir. 

For soil and water-based plants, mix the supplement in water and with the help of a watering can apply it directly to the plant. You can also use calmag to boost the growth of the plants by mixing in an extra teaspoon before feeding other nutrients to the plants. Hydrate the plant as you normally would.

– Can You Mix Cal-Mag With Nutrients?

Yes, you can mix cal-mag with other nutrients. The supplement acts as an amplifying agent, increasing the ability of plants to absorb nutrients better. Thus, adding it with other nutrients is beneficial to the plants.

– How Much Cal-Mag Should Be Used?

You just need a few teaspoons of calmag mixed in water for it to do the job. For hydroponic systems, mix in one teaspoon for every gallon of water in the reservoir.

For plants growing in soil or water, mix in a similar amount in one-gallon water and directly spray on plants. Additionally, as a booster or to accelerate plant growth, increase by another teaspoon in a gallon of water and apply just before the feed.

– Should I Use Cal-Mag Every Watering?

No, you don’t need to use the supplement with every watering unless there is a severe nutrient deficiency in the plant. You have to include it in regular watering only when the plant shows obvious signs of being unhealthy. Otherwise once a week should be perfectly fine when you can mix it with water and apply it to plants.

– When Should You Stop Using Cal-Mag?

Stop using cal-mag once the visible signs of a deficiency disappear. Adding in more continuously puts the plant at risk of being overfed with calcium which will result in increased soil pH levels. If your plant is looking healthy and thrives in every one of its cycles, then there is no requirement to add the supplement.

Should You Use Cal-Mag For Flowering?

Yes, you can use the supplement during the flowering phase of a plant especially if you notice the foliage browning or the buds falling off before time. Make a calmag solution in water and add it directly to the plant’s growing medium once a week. Along with this continue to hydrate the plant as you would normally do. 

Care to be taken not to make the tiny buds and flowers damp with the solution as during the flowering phase the foliage seldom likes to get wet. Monitor the flowering phase and the blooming to decide if the frequency of the supplement needs to be increased or discontinued. 

Best Time To Use it in Soil

Calmag supplements can be used with the base feed you provide to plants. Additionally, you can also begin using it when the plant is at the seedling stage.

This early usage of the supplement will ensure the plant benefits and the risk of a deficiency is reduced in the nascent stage of its life. Also, when using cal-mag, hard or untreated water is best avoided as these already contain enough nutrients and a high pH.

Flowering stages often are the time when a dip in the micronutrient level will be noticed. Hence, fill in the deficit at this stage before the condition becomes detrimental to the plant.

Monitor your plants regularly by doing a simple soil test for calcium and magnesium deficiency levels. A preventive measure such as this will always keep the plant healthy and lush green.

How To Make Homemade Supplement?

You can make a simple batch of cal-mag supplements at home using easily available ingredients. Here is the step-by-step procedure.

  • Keep the ingredients ready. You will need Epsom salts (magnesium sulfate) and a fertilizer containing calcium nitrate. 
  • Mix two parts calcium which will make 260 ppm and one part magnesium which will make 120 ppm. Stir this up well. You may need to adjust this ratio as per the nutrient levels you are trying to fill the deficit of. 
  • Dilute this with water and directly apply to plants.
  • Additionally, you can add nutrients such as Vitamin D and Iron to this pre-made home calcium-magnesium supplement. 
  • If your older leaves have already been affected with a deficiency, slightly increase the calcium amount to get them back in form and reduce discoloration and root rot.

Natural Cal-mag for Plants

You can also use other natural cal-mag ingredients and go organic for your plants. Here are a few easily available natural calmag options that you could go for. 

– Lime

This is one of the best cal-mag supplements for plants. There are various forms of lime or calcium carbonate that you can opt for such as mined limestone or garden lime and get a good boost for your plant, making the soil less acidic by increasing its pH.

– Dolomite Lime

Another form of calcium carbonate, dolomite lime also consists of magnesium carbonate and can be a great option if your soil is low in both nutrients. However, if a soil test shows higher magnesium levels than what is required, it is best to avoid dolomite lime and opt for another product.

– Gypsum

Gypsum is a fast-acting supplement that fills the nutrient deficit easily in the soil. However, do note gypsum does not alter pH levels, so if that’s a priority as well along with tackling the deficiency, it is best to avoid this product.

– Ground Oyster or Clam Shell Flour 

Ground Oyster and clamshell flour is an amazing source of calcium carbonate found naturally. The shells have low solubility and thus may take a long time to be effective in providing the nutrient or altering pH. Ground oyster is an ideal option if you include them in the soil during the plant’s nascent stage.

– Wood Ashes

Hardwood ashes are a source of calcium carbonate and also increase pH levels. They are slow in their process and not as effective as Lime. Do note that softwood ashes are not a recommended source of calcium for your plants. SO it is best avoided.

– Soft Rock or Colloidal Phosphate 

This is a source of calcium oxide and is also known as rock phosphate. It releases calcium slowly and in comparison to lime is less soluble. Rock phosphate has a moderate ability to raise pH levels.

– Bone Meal

An easy-to-make and natural supplement it is prepared by crushing bones into a fine powder. This is rich in phosphorus and calcium and moderately increases pH levels. It is highly beneficial to tumors, bulbs, and roots where the soil prefers a slower release of nutrients.

– Calcitic Lime

A calcium carbonate option has a high ability to fill in the deficiency fast and also raise the pH of the soil. Thus, it is an ideal option for acidic soils rather than alkaline soils. Do check your soil before you decide to use it on the plant.

– Calcium EDTA

This is a water-soluble form of calcium and is lighter on the soil without leaching any other elements present. 

– Egg Shells

Easily available, it is a natural form of calcium that works wonders for indoor plants. Powdered eggshell makes for excellent organic compost as well, which decomposes slowly filling nutrient deficits slowly and easily.

Can Cal-mag Harm Plants?

No, cal-mag will not hurt nor harm plants as its components do not affect the macronutrients such as the Nitrogen, Phosphorus, and Potassium ratio. It aids the macronutrients to function better and helps the plant thrive and grow healthy. Just ensure you don’t overdo the supplement as this may have detrimental effects on the plant.

An overdose leads to an increase in calcium levels which will elevate the soil pH so much that the plant will wilt and die. Calmag is necessary for the right dose to ensure the plant remains super healthy, so do not overdo it.

Does Cal-Mag Go Bad?

Cal-mag can go bad, though it will take a long time to do so. The product has an extensive shelf life and can be safely used for several years. Ensure you store it well in a cool and dry condition to prevent evaporation of its components.


Do I add Calmag to plants before or after nutrients?

Add Calmag to plants before nutrients to prevent nutrient lockout.

Can Calmag be used when my plant is flowering?

Calmag can be used during flowering to prevent calcium and magnesium deficiencies.

Does a plant need Calmag when growing in water?

Plants growing in water may still need Calmag as it provides essential nutrients that may not be present in the water.


Calmag for plants is a good supplement to use to overcome nutrient deficiency and to give its growth a little boost. Let us take a quick recap of all that we have learned from this article.

  • Calmag prevents deficiencies and fills in the gap in plant micronutrients of calcium, magnesium, and iron.
  • It aids in producing bigger blooms and better yields for the plant.
  • The common symptoms of such a deficiency are slow or stunted growth, darkened foliage, and flowers that don’t bloom.
  • You can use the supplement with hydroponic plant systems and in the soil by mixing it with water and directly applying it to plants. You can either make your supplement at home or use natural substances such as gypsum, bone meal, or powdered eggshells.
  • Calmag does not hurt plants as it retains the macronutrients of NPK in the soil. Ensure there isn’t any overdose as this may increase the level of calcium that could eventually kill the plant.

Whether you want to have a healthy bloom or greener foliage, calmag is an ideal solution for you. Now having read this article you can easily fulfill your plant’s requirements and watch them grow healthy and thriving.

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