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Using Calcium in the Garden for Healthy Plants

Using Calcium in the Garden for Healthy Plants

Mary Smith |

Have you ever added Oyster Shell Fertilizer to your soil?  Wondering WHY we add calcium?  Well here ya go!

Calcium is a component of plant cell walls, and it’s needed for enzyme formation and nitrate uptake. Oyster Shell is ground up into a powder and used as a natural and organic source of Calcium!  Organic calcium can also be used to help neutralize excessively acidic soils, which is especially important when you’re growing green, leafy vegetables like lettuce and spinach, or cruciferous vegetables like cabbage, broccoli, cauliflower, and kale.
KALE in the garden

Calcium carbonate is used to help prevent the spread of various diseases, such as powdery mildew, black spot, and blossom end rot. Other benefits of calcium include, protection from heat stress, increases metabolic functions in plant cells,  leading to a greater intake of other nutrients such as nitrogen and phosphorus.  Natural, organic source of calcium is used to correct Ca deficiencies and raise pH in acidic soils.


RADISH!  If you grew spindly radish or your radish did not form a "bulb," that usually means that your soil in calcium deficient.  This is an indicator that other plants might be suffering as well.

Organic calcium sources include dolomite lime, calcite, ground oyster shell (oyster shell flour), and crushed eggshells.

We eat eggs here but not near enough to supply our gardens with calcium.  So we substitute with Ground Oyster Shell.
If you experienced issues with "Blossom End Rot" then adding calcium to your soil might greatly improve your harvest!  Blossom End Rot: "This funky-sounding plague is a disease in tomatoes due to a calcium deficiency (or a watering issue). It manifests itself as a watery spot near the blossom end (the bottom, the butt, etc) when the tomato has begun to develop. Eventually, the spot will spread like a cancer. And it will be game over for that fruit."
The black spot will spread, eventually rotting the entire tomato
SQUASH can also be affected by calcium deficiency.

Calcium plays a pivotal role in the development of cells in plants. Bell pepper plants need calcium to produce fruits that have thick, sturdy walls. The thick walls are good for the health of the plant, as they are better able to resist rot and other diseases. Well developed peppers are also good for you, as the fruit has a better taste and flavor.
Blossom End Rot is a sign of calcium deficiency in Peppers as well.
Are you seeing the pattern here?  Instead of waiting until you see a sign of distress in your plants, Plan ahead and boost your soil health.

Oyster Shell flour
Applying Oyster Shell Flour to you soil
For new container gardens, add 1 tablespoon per gallon of soil. 
For new gardens:

2 lbs /100 sq ft, depending on soil analysis and crop. Repeated applications may be needed to fully adjust pH and Ca levels.
Adjust down if you have already applied calcium to soil or if you are using additional amendments with calcium included.
How to Apply
Mix into top 4-6" of soil for planting preparation
Side-dress around single plants or along plant row for established plants, 2-4" from plant stem; lightly scratch in to soil (maximum soil contact)
Water in after application

I hope you have enjoyed another educational article and video.  Please share so that we may help more people grow their own organic food!



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1 comment

Our garden is in need of fertilizer help. Our tomatoes were lacking something, kept having white hard spots in the outer part. My husband bought something that seemed to help. Great post. Please come share this Sunday at Family Joy blog linkup at http://www.pursueyourproject.com

Charlotte Burkholder,

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