Foliar feeding with calcium is one of the most popular ways to feed your tomatoes. It’s very easy and it works well if done correctly. If you are new to fumigation, then you might want to read our first article on fumigants before reading this article. You will learn what they are, why they work, how to use them effectively and how long they last in your greenhouse or outdoor garden.

Calcium is a necessary nutrient for plant growth. Without it, plants cannot grow properly. Calcium deficiency symptoms include yellowing leaves and stems, stunted growth and poor fruit set. Too much calcium can cause leaf burn and wilting, which may result in death of the affected plants. Calcium toxicity causes a variety of other problems including loss of vigor, early flowering and reduced yield potential.

There are several types of calcium fertilizers available on the market today. Some contain only trace amounts of calcium while others have added ingredients such as magnesium sulfate and potassium carbonate. The type of fertilizer you choose depends upon the amount of calcium you need to add to your soil and the kind of plant you’re trying to keep healthy.

The three most common types of calcium-based fertilizers are:

Dolomite Lime – Also known as “high-calcium lime,” the addition of magnesium carbonate to dolomite lime increases the amount of calcium relative to magnesium. Unlike other types of lime, it doesn’t release potassium, so it’s not recommended for use in soils that are high in potassium.

Dolomite limestone contains relatively large amounts of calcium and small amounts of magnesium. It is used to raise the pH of acidic soils and provides calcium and magnesium to plants in readily available form.

Rock Phosphate Lime – Rock phosphate is a good source of readily available phosphorous for plants, but doesn’t contain much calcium. You’ll need to add dolomite lime if you’re looking to increase the amount of calcium in the soil. Rock phosphate is moderately pH neutral.

Plant Food – Most commercially prepared plant foods contain small amounts of calcium. Look for a fertilizer that is higher in phosphorous and potassium if you want to boost the levels of those nutrients in the soil.

How Much Calcium Do My Tomatoes Need?

– In most cases, calcareous soils contain enough calcium to meet tomato (and most other plants) needs. But if your plants show signs of calcium deficiency (such as yellow leaves and stunted growth) you can add calcium to the soil or feed it to the plant in the form of a fumigant.

Of course, if you’re growing hydroponically, you can completely skip this step and go right to feeding your plants calcium using a hydroponic fertilizer.

How Do I Add Calcium To My Soil?

Calcium is released into the soil by calcium-rich materials such as limestone, bone meal and dolomite. Calcium is absorbed by acidic components such as coffee grounds, manure and dried blood.

Gardeners usually add ground limestone to sandy soils that have a low pH. The limy soil is neutralized when rain or watering causes the acidic compounds to leech out into the surrounding environment.

Foliar Feeding With Calcium: How To Make Your Own Calcium Fertilizer on

You need to take care when adding large quantities of calcium to soil since it can prevent other nutrients, such as nitrogen and phosphorous from being absorbed by the plant. For best results, add small quantities of dolomite or ground limestone to your soil little by little and mix well into the top layer of soil.

How Do I Feed My Plants With Calcium?

Plants can absorb nutrients from the soil through their roots, or from hydroponic solutions. When growing in soil, root-feeding plants will show signs of deficiency long before leaf-eating plants. This is because the roots are being starved long before the above-ground parts of the plant are affected.

For most plants, a liquid calcium solution, or a fumigant (in the form of a gas) is the best way to add calcium to their diet. Fumigate the soil once every two weeks or so to keep the level of calcium in the soil high enough to ward off problems.

Soil Application – Liquid calcium products are acidic and should be added to water before being poured onto the soil around your plants. Use a tablespoon of cal-sulfate (a common fumigant) for every gallon of water you use to irrigate your plants.

Frequency of use – Apply the fumigant to your plants every three or four days.

Hydroponic Application – When using a hydroponic solution you should mix 1 tablespoon of cal-sulfate to every 2 gallons of water.

Frequency of use – Since hydroponic solutions are added directly to the plants’ roots, they tend to be more effective than soil applications. Use the fumigant once every two weeks.

Note: Remember, over-fumigating your plants can be just as bad for them as not fumigating at all. Use the above recommendations as guidelines and then adjust the schedule to match your plants’ needs.

How Do I Know If My Tomatoes Are Getting Enough Calcium?

Symptoms of a calcium deficiency in tomatoes are:

Yellowing of the leaves (not just the edges)

Leaves with a sandpaper-like texture

Slow growth of the fruit

Problems with ripening (including splitting and cracks)

If you look carefully at your tomato plants, you’ll be able to tell if they have a calcium deficiency.

What If I Don’t Have the Time or Room To Grow Other Plants?

If you want to grow tomatoes but you don’t have the space to grow other plants or you don’t have time to care for them, it’s perfectly okay. You can always buy ‘tomato meals’ to add to your soil. These meal replacements contain all the nutrients that a tomato plant would get from ‘regular’ food (fruits, veggies, meats and grains).

But make sure you add other minerals and nutrients as well. Check the NPK on the bag. It should be around 5-5-5. If it’s lower than that, you should add something else (like bone meal or blossom dust).

You can also buy ‘tomato growth stimulators’ at most garden stores. These usually contain magnesium, nucleic acids, ammonium phosphate and other nutrients that help with photosynthesis and plant growth. These are a really great addition to your soil, so consider buying some.

Foliar Feeding With Calcium: How To Make Your Own Calcium Fertilizer -

If you want to be sure that your tomato plants get everything they need, you can always buy a ‘tomato plant food’. These usually contain all the nutrients and supplements a plant could ever need.

What Are Blossom Dust And Wood Ash?

Blossom dust looks like fine white powder. It’s made from dried-out blossoms (obviously). It contains calcium and magnesium – two nutrients that tomatoes really like. Use it at the rate of 1 teaspoon per plant.

Wood ash is made from, well, wood ash. It’s not dangerous unless you’re incredibly unwise and decide to hold an ash pile in your hand, which is likely to get hot! As with most other things, you don’t want to hold it in your hand while you’re gardening. However, wood ash does offer a wide range of nutrients for your tomato plants. Use it at the rate of 2 tablespoons per plant.

How Do I Get My Tomatoes Ready For Canning?

Once you’ve picked them and gotten them home, you’ve still got some work to do before canning. You should always rinse off your tomatoes (as well as any other produce you’re going to put up).

Sources & references used in this article:

Foliar feeding of potassium, calcium, zinc and copper in improving the chemical composition of fruits in Litchi cv Bombai. by MDA Hasan, A Jana – Environment and Ecology, 2000 –

Foliar application of potassium, calcium, zinc and boron enhanced yield, quality and shelf life of mango. by B Arvind, NK Mishra, DS Mishra… – HortFlora Research …, 2012 –

Effects of pre-or post-harvest application of liquid calcium fertilizer manufactured from oyster shell on the calcium concentration and quality in stored’Niitaka’pear fruits. by BW Moon, ST Lim, JS Choi, YK Suh – … of the Korean Society for …, 2000 –

Effect of some sources of potassium and calcium as a foliar spray on fruit quality and storability of” Kelsey” plums. by AA Abdel-Hafeez, AI Mohamed, NM Taha… – Egyptian Journal of …, 2010 –

Effects of fertilizers containing calcium and/or magnesium on the growth, development of plants and the quality of tomato fruits in the western highlands of Cameroon. by J Aghofack-Nguemezi, V Tatchago – International Journal of …, 2010 –

Response of Tomato to different levels of calcium and magnesium concentration. by I Mohammad, A Gohar, H Zahid, A Manzoor… – World Applied …, 2014 –

High rates of nitrogen on tea. 3. Monthly changes in mature leaf calcium, magnesium, manganese and aluminium contents. by JK Wanyoko, PO Owuor, CO Othieno – Tea, 1990 –



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