How to Add Calcium to Soil: 6 Ways to Add Calcium to Soil

Calcium is an element, one of the most abundant metals on Earth. In gardening, calcium is a secondary macronutrient. This means that it’s important but not as essential as the primary nutrients—nitrogen, potassium, and phosphorus. Plant growth and overall health requires a certain amount of calcium.

Calcium is one of the factors that determine the pH level of the soil, which has to be the right balance of acidity and alkalinity. Many plants, especially those grown in the garden, prefer a slightly acidic soil.

• Plant growth: Calcium promotes the growth of plant tissues and membranes and the strengthening of cell walls.
• Root systems: Enzymes necessary for cellular activity within the plant also depend on calcium for development. This is especially important for the development of root systems, which uptake various nutrients.
• Protection: Calcium is a deterrent for chewing pests and microorganisms.
• Nutrition: In addition to the health of the plant, calcium also makes the plant itself more nutritious, whether it’s being consumed by animals in a healthy wild ecosystem, livestock, or humans.

If your plants are low in calcium, you may start to notice stunted growth, curling or withered young leaves, or leaves with burnt-looking edges, a condition called tip burn. Eventually, symptoms will be obvious. For example, a tomato plant lacking calcium will exhibit blossom end rot, which is when the end of the fruit will darken and die off.

You can also determine a calcium deficiency with a soil test, which will provide an overall profile of your soil and let you know your soil’s cation exchange capacity (CEC). Soil amendments increase the CEC, the storage of key plant nutrients such as calcium, magnesium, potassium, and phosphorus. You can perform an at-home test or submit a soil sample to a nursery or online service for professional testing.

There are different ways to add calcium to garden soil, depending on the state of your soil. It’s good to start with a solid foundation of healthy soil, then add calcium fertilizer as needed. Consider these methods:

• Foliar spray: You can add calcium via a spray that contains calcium chloride, calcium acetate, or calcium nitrate. This method is quick-acting and useful on plants showing an obvious and pronounced deficiency of calcium. In the case of sprays, plant leaves absorb the calcium directly.
• Lime: Calcium carbonate, commonly sold as lime, is a good source of calcium you can add to your soil. Keep in mind that It will raise the pH of your soil. A variation on this is dolomitic lime, which also contains magnesium, which can be useful if your soil also has low levels of magnesium.
• Bone meal: Made of the ground-up bones of animals, bone meal is a good soil additive that can raise the calcium levels in your soil. Bone meal works slowly, raising calcium levels gradually over an entire growing season.
• Eggshells: Eggshells are a slower way to add calcium to soil than bone meal, as they have to break down for the calcium to become available for use by plants. You can can add eggshells to the soil when planting seedlings, or you can add eggshells to compost then add the compost to soil when it’s ready, or you
• Wood ashes: Wood ashes from hardwoods are good for soil amendment. Keep in mind that wood ash will also raise the pH of your soil.
• Gypsum: This form of calcium sulfate is a good to add if soil pH is a concern; unlike a lot of other additions, gypsum is pH neutral.

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