Do you remember when you were a kid, and you were always told to finish your milk because you needed calcium to build strong bones?

As adults now, we take calcium supplements if we don't get enough dairy products. Turns out you need calcium even after your bones have stopped growing. Well guess what, plants need calcium too. Calcium is the “building block” nutrient that gives plants structural integrity and helps them function at a cellular level. A lack of it quickly affects the quality and yield of fruits, vegetables, and overall plant health. Here are some signs that can tell you your plants need calcium: blossom end rot in tomatoes, peppers, zucchini.

Tip burn on lettuce, cabbage, and strawberries. Distorted, curled, or chlorotic new leaves. Stunted root growth. Poor fruit set or fruit cracking and increased susceptibility to diseases. So how do you get calcium back into your soil? Anyone who has a compost pile for kitchen waste will tell you that eggshells are the best way to add calcium back into the soil. Eggshells are nearly pure calcium carbonate. Just rinse and dry them, then crush them up for faster breakdown in the garden. You can use them without rinsing, the putrescent smell that they will create will also deter deer and people. So don't use near the deck or patio.

Bone Meal, a natural organic fertilizer made from steamed and ground animal bones is high in both calcium and phosphorus. The high phosphorus will benefit any plant that fruits or flowers. Garden Lime is Calcium Carbonate and is the easiest way to add calcium as well as raising the pH of your soil. The only downfall is if too much is applied you can make your pH too high.

If you need to add calcium and your pH is fine already then use Garden Gypsum which is calcium sulfate. Gypsum adds calcium without significantly changing soil pH. Gypsum is best for neutral or alkaline soils, or soils with high sodium as gypsum helps displace sodium, like road salt near the edge of your lawn. And it also improves soil structure in clay soils as it breaks down clay into a more loamy soil. Hydrated lime will add calcium to soil as well, but it will affect pH more quickly and strongly than garden lime and should be used with caution. Lastly, there is liquid calcium that can be sprayed on or watered into the plants. Foxfarm has a product called Cal/Mag which is a liquid Calcium Magnesium supplement used predominantly in hydroponics but can be used in gardens and flowerbeds as well.

Here are some important facts about calcium and plants. Calcium is immobile in plants. Once it’s fixed in older leaves, it cannot be moved to new growth. That’s why new tissues show deficiency first. Plants absorb calcium as Ca²⁺ ions through the roots, mainly via mass flow with water, good afternoon thunderstorms will do the trick. Consistent soil moisture is important for uptake, so water early in the morning if we don't have a storm the day before. Calcium availability is heavily influenced by soil pH and is best absorbed in slightly acidic to neutral soils with a pH range of pH 6.0–7.0. So, make sure your plants are getting the right amount of calcium so they can grow big and strong.