Calcium Nitrate Fertilizer - Uses, Pros, Cons, and Application Rate

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by Max - last update on March 3, 2020, 8:01 pm
Calcium Nitrate Fertilizer

Ensuring your plants have a healthy balance of nutrients is vital in promoting good growth. The proper balance of nutrients will also help a plant to resist disease, produce a greater abundance of flowers, and more high-quality fruits.

But which nutrients do your plants need, and are all plants nutrient requirements alike? Calcium nitrate fertilizer is one source of plant food you may have heard of that is especially beneficial for crops such as pepper and tomato plants and apple trees. But what actually is calcium nitrate fertilizer? How can it benefit your plants, do you need it, and how can it be used? Read on to find out.

What Is Calcium Nitrate Fertilizer?

Calcium Nitrate fertilizer

Calcium nitrate fertilizer is a synthetically derived compound, which takes on the appearance of salt. It is commonly used in fertilizer solutions, or as a fertilizer in its own right, for house plants, garden plants, and crops. Calcium nitrate is the only water-soluble source of calcium and is therefore often used in liquid fertilizers or as a foliar spray to be applied directly to plant leaves.

Why Use Calcium Nitrate Fertilizer?

Calcium nitrate contains both calcium and nitrogen, which are nutrients plants require to survive. Calcium is vital for some plants to be able to produce seeds, and it also helps a plant to produce a better quality of fruit with a longer shelf life. Calcium is also an important element in the formation of plant cell walls, and the proper availability of calcium in a plant will help to ensure cell walls are strong, protecting the plant from disease and stressors.

Nitrogen is understood by most gardeners to be an essential nutrient which plants need generous quantities of. Nitrogen is a vital component in the production of amino acids and chlorophyll, and a good supply of nitrogen will generally result in a lush and green plant, which is visibly thriving. Calcium nitrate can be used to fertilize any plants, but there are some situations when it is particularly useful.

Calcium-Deficient Plants

Some plants can suffer from calcium deficiencies, especially those in poor quality soils where calcium may be naturally lacking. Even in good quality soils, calcium availability will decrease over time, so using a balanced fertilizer with all of the necessary nutrients is important. Some plants are more prone to calcium deficiencies than others, such as tomato plants, which can suffer from calcium deficiency as a result of heat stress. If you have a plant with a calcium deficiency, you may notice symptoms such as flowers prematurely falling from the plant or foliage curling inwards on itself.

Calcium deficiencies in apple trees will typically lead to a particular problem with the fruit, called cork spot. It’s very hard to judge whether a plant is nutrient deficient just by looking at it, and it is advisable to get your soil, or the plant itself, tested for deficiencies before you try to self-medicate the plant. If you do discover a lack of calcium, then calcium nitrate is a good way to resolve this. For a quick fix, spray calcium nitrate directly onto the leaves and fruits of the plant, as this will take effect more quickly than calcium nitrate applied at the roots.

Nitrogen-Deficient Plants

Nitrogen is a macronutrient that plants require, typically in much larger quantities than other nutrients. A nitrogen deficient plant will exhibit symptoms such as slow growth, and a lack of new shoots appearing. Nitrogen deficiencies can also cause pale-colored leaves, and a slow down in leaf production. Ammonium nitrate is often given to plants as their source of nitrogen, but this isn’t always the best idea as the ammonium can interfere with the plant's calcium absorption.

Although it may fix the nitrogen deficiency, ammonium nitrate can cause other problems if it inhibits a plant's calcium uptake. Instead, calcium nitrate works as a better fertilizer, supplying the necessary nitrogen without causing calcium issues. Calcium nitrate is especially recommended for use in plants that are more susceptible to calcium deficiencies.

Disease Prevention

One of the main reasons why many gardeners treat their plants with calcium nitrate fertilizer is to protect their plants and crops from disease. Blossom end rot, cork spot, and bitter pits in apples can all be prevented or treated with the use of calcium nitrate fertilizer.

Blossom end rot is a common problem for tomato growers, which exhibits itself as damp spots on the underside of the fruit. Blossom end rot will cause a tomato to look unappealing and become inedible. As the fruit grows, it will become sunken and take on a tough, leathery look. It is usually caused by a lack of calcium availability and can be successfully treated with a calcium nitrate foliar spray. You can also treat your soil with a calcium nitrate fertilizer to help prevent blossom end rot from becoming a problem again next growing season.

Cork spot and bitter pits are problems affecting apples, and both can be caused by calcium deficiencies.  Cork spot typically starts to show on apples in June and worsens as the summer goes on. The problem appears as discolored depressions on the fruit, and they can range in size. While they don’t affect the taste of the apple, they do interfere with its visual appeal. Bitter pit presents itself as pockmarks on the skin of the apples and causes brown spots on the flesh of the fruit.

Like cork spot, bitter pit makes the fruits look unappealing, but unlike cork spot, bitter pit does interfere with the taste. Apples with bitter pit will have a bitter flavor, and though they will still be perfectly safe to eat, you will probably want to avoid them. Both of these problems are associated with a lack of calcium and can be remedied with the use of calcium nitrate fertilizer (SF Gate).

What is Calcium Nitrate Made Of?

Calcium nitrate is not organic and instead is a synthetically derived compound with the chemical formula Ca(NO3)2. It is made by applying nitric acid to limestone and then neutralizing it with ammonia.

Pros and Cons of Calcium Nitrate

  • Good source of calcium
  • Good source of nitrogen
  • Water-soluble
  • Can be used as fertilizer and disease treatment
  • Can be used as a foliar spray, soil drench, and top dressing
  • Inexpensive
  • Not organic
  • Less effective on outdoor plants compared to houseplants

How to Use Calcium Nitrate in the Garden

Calcium Nitrate Fertilizer Application Rate

To mix your own calcium nitrate fertilizer for the treatment of diseased plants, add four tablespoons of calcium nitrate salts to one gallon of water, and mix. To use calcium nitrate fertilizer as a disease preventative, or to balance out the nutrient levels in your plants, use one tablespoon of calcium nitrate to each gallon of water.

How to Apply Calcium Nitrate Fertilizer

Calcium nitrate fertilizer can be applied in different ways, based on its purpose and your preference. For fruits that are already affected by a disease such as blossom end rot, a foliar spray will be the best way to treat the plant. This ensures the calcium is absorbed by the plant as quickly as possible. Mix up your calcium nitrate fertilizer, then spray it generously on the fruits and foliage of your plant. Repeat this process two or three times a week throughout the growing season.

A foliar spray of calcium nitrate fertilizer can also be used to treat the calcium or nitrogen deficiency of any plant. Spraying the foliage is preferable to treating the soil for plants that already show signs of nutrient deficiencies, as this is the quickest way to get the nutrients into the plant's system.

For fertilization and disease prevention, you can also use calcium nitrate fertilizer as a top dressing or side dressing, as a more slow-release option. To top dress the plants, you can use calcium nitrate fertilizer in its solid form. Use around half an ounce of salts for each square foot of soil, working it into the top inch of soil around the plants and taking care to avoid it coming into contact with any of the plant's leaves.

To side-dress your plants, follow the same guidelines, but instead of applying it throughout the top layer of soil, apply it in lines or circles around the outer edge of a plant’s base. After top dressing or side dressing your soil, water the soil well to encourage the nutrients to seep into the lower layers and reach the roots of the plants.


Calcium nitrate fertilizer is a multi-purpose fertilizer which can be utilized in feeding plants as well as treating or preventing disease, particularly among fruiting plants. It contains both calcium and nitrogen and can, therefore, be used to treat plants that have deficiencies of either of these nutrients. It is a common component or commercial balanced fertilizers, but can also be easily mixed at home for specific purposes, for use as a foliar spray or in soil dressing.

Calcium Nitrate Fertilizer - Uses, Pros, Cons, and Application Rate

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