This article may contain affiliate links. Please read our disclosure for more information.

Are you looking to add calcium to your soil and improve the health and growth of your plants?

There are several ways to add calcium to soil, including using calcium supplements, organic materials, and adjusting soil pH. But what’s the best method for your particular plant? 

In this article, I’ll explore the different ways to add calcium to soil, the benefits of calcium for plant growth, and provide you with a little-known secret to boost your plants’ calcium uptake. 

Keep reading to discover how you can transform your plants so they’re thriving and healthy!

a woman planting a monsterra and add calcium to soil

How to add calcium to soil

Adding calcium to soil is a critical aspect of promoting healthy plant growth and improving soil health. Fortunately, there are several effective ways to add calcium to soil that any gardener can use to get excellent results:

  1. Calcium-rich fertilizers like gypsum, dolomite lime, and calcium nitrate, which are readily available (my favorite gypsum soil amendment is here). These fertilizers can be applied according to the manufacturer’s instructions, with calcium nitrate being particularly effective as a foliar spray directly onto the leaves of plants.
  2. Crushed eggshells, which are rich in calcium carbonate and can be added to soil after being collected, cleaned, and crushed into small pieces. As the eggshells gradually break down, calcium is slowly released into the soil.
  3. Bone meal is a slow-release fertilizer made from ground-up animal bones that is rich in calcium, as well as other essential nutrients like phosphorus and nitrogen. This organic bone meal is excellent for boosting your plant’s health. Mixing bone meal into the soil according to the manufacturer’s instructions is an effective way to add calcium to soil over time.
  4. Natural amendments like oyster shells, clamshells, and limestone are rich in calcium and can be mixed into soil to increase its calcium content. However, it’s important to note that these amendments can increase the soil’s pH, so it’s essential to test the soil’s pH before using them.
  5. Adding compost to soil is an excellent way to increase its calcium content while also improving soil health. Compost is a rich source of nutrients, including calcium, and can be added to soil regularly.

Remember that different plants require varying amounts of calcium, and excessive amounts can cause imbalances in soil nutrients, so it’s essential to follow instructions carefully when adding calcium to soil. 

By using a combination of these methods and promoting healthy microbial activity in the soil, gardeners can improve soil health and promote healthy plant growth.

egg shell that can add calcium to soil

What is the best source of calcium for plants?

Calcium-rich fertilizers, such as gypsum, dolomite lime, and calcium nitrate, are some of the best sources of calcium for plants. These fertilizers can be easily found at most gardening centers and can be applied to soil according to the manufacturer’s instructions. 

My recommended gypsum soil amendment is this one:

Calcium nitrate is also really effective as a foliar spray applied directly onto the leaves of plants. This one is great value and very highly rated.

Compost is another great source of calcium for plants. By composting organic matter like kitchen scraps, yard waste, and manure, we create a nutrient-rich soil amendment that can be added to soil to increase its calcium content. 

What’s great about compost is that it’s also a fantastic source of other essential nutrients, including nitrogen and phosphorus.

Either way, when choosing the best source of calcium for plants, it’s important to keep in mind that different plants require different amounts of calcium. 

Also, be sure to follow instructions carefully when adding calcium to soil and avoid overuse, as excessive amounts of calcium can lead to imbalances in soil nutrients and other issues. 

What fertilizer is high in calcium?

If you’re looking for a fertilizer that’s high in calcium, then you’re in luck – there are several options to choose from!

Gypsum is a slow-release fertilizer that’s high in calcium and can help improve soil structure and drainage while providing calcium to plants. It can be applied to the soil in a granular form or as a powder, following the manufacturer’s instructions.

Dolomite lime is another great option, as it’s high in both calcium and magnesium. It can help balance soil pH while providing calcium to plants. Dolomite lime can be applied to the soil in a granular form or as a powder, according to the manufacturer’s instructions.

Calcium nitrate is a water-soluble fertilizer that contains both calcium and nitrogen. It’s particularly effective as a foliar spray directly onto the leaves of plants, allowing for quick absorption of calcium. Calcium nitrate can also be applied to the soil in a granular form or as a powder.

a compost that can add calcium to soil

Bone meal is a slow-release fertilizer made from ground-up animal bones that’s rich in calcium, as well as other essential nutrients like phosphorus and nitrogen. Mixing bone meal into the soil according to the manufacturer’s instructions is an effective way to increase calcium levels in soil over time.

Fish bone meal is another slow-release fertilizer made from fish bones that’s high in calcium and other essential nutrients. It’s often used in organic gardening and can be mixed into soil according to the manufacturer’s instructions.

Last but not least – and as mentioned before – compost is a natural fertilizer that’s high in calcium and many other essential nutrients. By composting organic matter like kitchen scraps, yard waste, and manure, you can create a nutrient-rich soil amendment that can be added to soil to increase its calcium content.

How do I know if my plants need calcium?

Plants deficient in calcium can display several symptoms. Young leaves may curl, become distorted, or develop necrotic spots. Leaves may also turn yellow, and stems may become weak and spindly. Fruit may also develop blossom end rot, which is a dark, sunken lesion that appears on the bottom of the fruit.

So if you’re wondering whether your plants need calcium, there are definitely a few signs to look out for.

Another sign that your plants may need calcium is a slower growth rate. Plants deficient in calcium may produce fewer flowers or fruits and have smaller leaves.

Pro tip: A soil test is an excellent way to determine if your soil is deficient in calcium. They’re great value and can provide accurate results in minutes. 

You can check the latest price of this soil kit here to get started.

If the test shows low calcium levels, you’ll need to increase the calcium content of the soil using fertilizers like gypsum or dolomite lime.

It’s important to note that some environmental factors, like high levels of salt in the soil, can affect a plant’s ability to absorb calcium, even if there’s enough calcium in the soil.

someone planting and added calcium to soil

If you suspect that your plants lack calcium, it’s essential to take action quickly to avoid further damage. Adding calcium-rich fertilizers, like gypsum or dolomite lime, is an effective way to increase the calcium content of the soil. 

Using organic sources of calcium, like crushed eggshells or bone meal, can also provide a slow-release source of calcium to plants.

Can too much calcium hurt plants?

While calcium is crucial for healthy plant growth, excessive amounts of it can actually harm your plants. Too much calcium can cause imbalances in soil pH and nutrient uptake, leading to nutrient deficiencies, stunted growth, and other symptoms. 

Additionally, high levels of calcium can interfere with the absorption of other essential nutrients, such as potassium and magnesium.

Another problem with excessive calcium is that it can lead to alkaline soil conditions, which can be problematic for plants that prefer acidic soil. High pH levels can make it difficult for plants to absorb nutrients from the soil, further inhibiting growth and development.

What happens if a plant gets too much calcium?

When plants receive too much calcium, it can lead to imbalances in nutrient uptake and alkaline soil conditions. Additionally, high levels of calcium can interfere with the absorption of other essential nutrients like potassium and magnesium, leading to stunted growth and yellowing leaves.

Excessive calcium can also cause physical damage to plants, resulting in discoloration, deformation, and other symptoms.

To prevent calcium toxicity, it’s important to use calcium-rich fertilizers and supplements in moderation and follow the manufacturer’s instructions. 

If you notice signs of calcium toxicity, such as distorted leaves, poor growth, or yellowing, it’s best to stop using calcium-rich supplements and make adjustments to the soil as needed.

How much calcium does my soil need?

To determine how much calcium your indoor plants need, several factors come into play, including the type of plants you’re growing, the potting mix you’re using, and the existing calcium levels in the soil. Your first step in figuring this out should be to do a soil test.

Conducting a soil test can help you identify the current calcium levels in your soil and determine the appropriate amount of calcium needed for your specific plants. 

Researching the specific calcium requirements of your plants is also important to ensure optimal growth.

Indoor plants need moderate levels of calcium to support healthy growth and development. Some plants, such as tomatoes, peppers, and citrus trees, require higher levels of calcium than others.

someone holding a plant  in a pot with sun drawing

It’s also essential to consider the potting mix when determining the appropriate level of calcium for your indoor plants. Some potting mixes may contain low levels of calcium, so it may be necessary to add a calcium supplement to ensure your plants have adequate calcium levels.

When adding calcium to your indoor plants, it’s important to use it in moderation and follow the manufacturer’s instructions carefully. As mentioned earlier, using excessive amounts of calcium can harm plants and cause nutrient imbalances.

How often should I add calcium to the soil?

In general, it’s a good practice to add calcium to soil once or twice a year, depending on your specific needs. Adding calcium in the spring before planting or in the fall can help ensure that your plants have access to the necessary nutrients throughout the growing season.

The type of calcium supplement you’re using can also influence how often you should add it. Some supplements, like dolomite lime or bone meal, release calcium slowly over time, so they may not need to be added as frequently. 

Other supplements, such as gypsum or calcium nitrate, may need to be added more frequently to maintain adequate levels of calcium in the soil.

a woman planting and added calcium to soil

The frequency of adding calcium to soil can vary based on several other factors too, such as the type of plants you’re growing, the type of soil you have, and the current level of calcium in the soil.

To determine if your soil needs calcium, it’s best to conduct a soil test to measure the pH level, nutrient content, and other factors that can impact plant growth. If the soil test reveals that your soil is deficient in calcium, it’s recommended to add calcium as needed.

What are the other benefits of adding calcium to soil?

Adding calcium to soil offers several benefits beyond the essential role it plays in cell wall formation and strength. Here are some of the other benefits of adding calcium to soil:

  • Improves soil structure: Calcium helps improve soil structure by promoting the formation of aggregates, which can improve soil porosity, water infiltration, and aeration. Additionally, calcium can stabilize soil pH and reduce soil compaction.
  • Enhances nutrient uptake: Calcium helps regulate the uptake of other essential nutrients like potassium and magnesium, making them more available to plants. This can help improve plant growth, increase yields, and enhance the overall quality of the produce.
  • Reduces plant diseases: Calcium can help reduce the incidence of several plant diseases by strengthening cell walls, making them less susceptible to damage from pathogens like fungi and bacteria.
  • Increases drought tolerance: Calcium can improve the drought tolerance of plants by promoting deeper root growth and enhancing water uptake efficiency.
  • Enhances fruit quality: Adequate calcium levels in plants can improve the quality of fruits and vegetables by reducing the incidence of disorders like blossom end rot, which can cause fruit to become misshapen and unmarketable.

FAQs

How do you make homemade calcium for plants?

Crushed eggshells are an excellent source of homemade calcium for plants. Simply clean the shells, crush them into small pieces, and add them to soil or compost. As they gradually break down, calcium is slowly released into the soil.

Bone meal is another option. It’s a slow-release fertilizer made from ground-up animal bones that’s high in calcium, phosphorus, and nitrogen. 

To make homemade calcium for plants using bone meal, crush up clean animal bones and grind them into a fine powder. Then, mix the bone meal into soil or compost following the manufacturer’s instructions.

a woman holding a shovel adding calcium to soil

Milk is also a source of calcium that can be used for plants. Mix 1 cup of milk with 4 cups of water and then water your plants with the solution once a month to give them a calcium boost.

Tums are a calcium supplement that can be crushed up and added to soil or water to provide plants with calcium. Simply crush up a few Tums tablets and mix them into soil or water.

Can you add milk to soil for calcium?

While milk can be a good source of calcium for plants, it’s not recommended to add it directly to the soil. This is because milk contains natural sugars and proteins that can attract bacteria and insects to the soil, leading to root rot and other issues. 

When milk decomposes, it can also produce a foul odor that can be unpleasant and attract pests.

Additionally, milk contains high levels of phosphorus, which can lead to an excess of phosphorus in the soil and potentially harm your plants.

But don’t worry – there are still ways to use milk to provide a calcium boost for your plants! You can use it as a foliar spray or a soil amendment.

To make a foliar spray, mix 1 part milk with 2 parts water and spray the solution onto the leaves of your plants. This will provide a quick boost of calcium and other nutrients that will be absorbed through the leaves.

To use milk as a soil amendment, mix 1 part milk with 9 parts water and pour the solution around the base of your plants. This diluted mixture will add calcium and other nutrients to the soil without causing nutrient imbalances or attracting pests.

Will powdered milk add calcium to soil?

Powdered milk is a good source of calcium and other nutrients that can promote healthy plant growth. When added to soil, it slowly releases calcium and other nutrients as it decomposes. However, it’s important to use powdered milk in moderation to prevent nutrient imbalances.

Another thing to note is that powdered milk contains high levels of phosphorus, which can be harmful to plants if overused. So, it’s crucial to follow the manufacturer’s instructions and not overdo it.

someone planting and add calcium to soil

To use powdered milk as a fertilizer, mix it with water according to the instructions and pour the solution around the base of your plants. This will provide a slow-release source of calcium and other nutrients that will help your plants grow and thrive.

Will crushed eggshells add calcium to soil?

Yes, crushed eggshells are an excellent and cost-effective way to provide your plants with a source of calcium. When added to soil, they gradually release calcium and other nutrients as they decompose. One of the benefits of using eggshells as a source of calcium is that they’re readily available and free. 

So instead of tossing them out, clean and dry the eggshells, then crush them into small pieces using a blender or mortar and pestle.

To use crushed eggshells as a soil amendment, sprinkle them around the base of your plants or mix them into the soil. The eggshells will gradually break down, releasing calcium and other nutrients into the soil.

In addition to providing calcium, eggshells can also help improve soil pH. They are alkaline, so they can help neutralize acidic soils, which can benefit some plants.

However, it’s important to note that eggshells alone may not provide enough calcium for some plants, particularly those with high calcium requirements. In these cases, additional sources of calcium may be necessary.

Does tap water have enough calcium for plants?

No, while tap water may contain some calcium, the levels can vary depending on several factors, and they may not be sufficient to meet the calcium requirements of most plants. To ensure that your plants receive enough calcium, it’s recommended to supplement tap water with calcium-rich fertilizers or other sources of calcium. 

Another option is to use tap water in combination with other water sources that contain higher levels of calcium. 

Rainwater is an excellent source of calcium, and collecting it can provide a natural source of calcium for your plants.

someone watering plants

Does Epsom salt add calcium to soil?

No. Epsom salt, or magnesium sulfate, does not contain calcium, so it does not add calcium to soil. While Epsom salt is an excellent source of magnesium and sulfur, it does not provide the necessary calcium for healthy plant growth. 

Magnesium is an essential nutrient for plants, and sulfur is necessary for protein synthesis and other critical plant functions.

However, if your plants are displaying symptoms of magnesium deficiency, such as yellowing leaves or poor growth, adding Epsom salt to the soil can help supply the necessary magnesium. 

It’s essential to use Epsom salt in moderation and follow the manufacturer’s instructions carefully, as excessive amounts of magnesium can harm your plants.

Does bone meal add calcium to soil?

Yes, bone meal is a great source of calcium and can help add essential nutrients to your soil for healthy plant growth. Bone meal is made from crushed animal bones and contains high levels of calcium, phosphorus, and nitrogen.

Using bone meal to add calcium to your soil is a natural and effective way to supply your plants with the nutrients they need. You can add bone meal to your soil before planting or apply it as a top dressing throughout the growing season.

In addition to calcium, bone meal is also a good source of phosphorus, which is necessary for root development and overall plant growth. Using bone meal can help improve soil fertility, increase plant vigor, and promote better yields.

someone adding calcium to soil

Can I add too much calcium to the soil?

Yes. While calcium is essential for healthy plant growth, adding too much calcium to the soil can lead to nutrient imbalances and negatively impact plant growth. Excessive amounts of calcium can reduce the uptake of other essential nutrients like magnesium, potassium, and manganese, leading to nutrient deficiencies and poor plant growth. 

Additionally, too much calcium can increase the soil pH, making it more alkaline, which can also harm your plants.

In some cases, adding too much calcium to the soil can also cause soil compaction, reducing water and nutrient uptake and causing poor plant growth.

To avoid adding too much calcium to the soil, it’s essential to conduct a soil test to determine the current levels of calcium and other essential nutrients in the soil. Based on the soil test results, you can determine the appropriate amount of calcium supplement to add to the soil.