A ubiquitous sight in home gardens, tomato plants fill vegetable gardens around the world with bright red fruit, used in a seemingly endless variety of dishes. Though some see it as a delicate plant, tomatoes are resilient and sturdy. However, they can be susceptible to certain problems if their growing conditions are not ideal, one of which is blossom end rot.
At one point, your tomatoes look plump and perfect. Then, suddenly, you notice that the bottom of the fruit is turning brown and sunken in. The fruit starts to look mushy and unappetizing. This problem is called blossom end rot (BER), a common issue for tomato growers. Generally, this happens when your tomato plants are not getting enough calcium. Why does this happen, and how does calcium play a role in preventing BER?
Do Tomatoes Need Calcium? Role of Calcium in Tomato Plants
Aside from the top three nutrients (nitrogen, phosphorus, and potassium), all plants also need calcium. It plays a vital role in plant growth and development and is responsible for producing strong cell walls. Calcium is also involved in the regulation of water and nutrients uptake, as well as enzyme activity. All these contribute to a plant’s overall health.
Not all plants are responsive to calcium in the same way. For example, some plants may not significantly show any problems even when they lack calcium. In contrast, others like apples, potatoes, and tomatoes are susceptible to it.
In short, tomatoes heavily rely on calcium, especially during fruit production. The lack of it may result in mushy, deformed, and unmarketable fruits.
Calcium deficiency may also manifest in other ways, such as curling or cupping of new leaves, hollow stems, and in some cases, the lack of the vibrant red-orange color of ripe fruits.
When to Supplement Calcium for Tomato Plants
Tomatoes thrive well when they’re growing in soils with a pH level of 6.5 to 7.2. Anything lower than that might indicate that the soil is too acidic for tomatoes. When the soil is acidic, this may also suggest that the soil may lack calcium.
Supplementing calcium early during the season can help prevent blossom end rot from occurring. Calcium carbonate can help raise the acidity levels and the soil’s calcium levels at the same time. You can do this during the fall, right before you plant your tomatoes. This will give the calcium time to be absorbed by the soil before the planting season.
If, during the growing season, your tomato plants show signs of BER, you can still supplement your soil with calcium. Take note, however, that the spread of calcium during this period won’t be as effective as if you did it before planting.
To help your tomato plants absorb calcium more efficiently, you can also mulch around the soil, ensuring the soil is damp. Keep the soil’s moisture level consistent by watering your plants regularly. Plants are more likely to experience calcium deficiency when the soil remains consistently dry. This is one of the most vital steps in preventing blossom end rot.
Different Ways to Apply Calcium
Similar to other nutrients, there are different ways to apply calcium to your tomato plants. Calcium is best delivered through the roots. This means that spraying the leaves with any supplementary calcium spray won’t be as effective. Here are some different ways to help apply and raise the soil’s calcium levels:
Crushed Eggshells
When it comes to applying calcium to your tomato plants, one of the most common and simplest ways is to use crushed eggshells. I’ve seen most people sprinkle crushed eggshells around the base of the plant. However, for better results, you can also add this to your compost pile. This way, the eggshells will have enough time to break down and be easily absorbed by the roots come springtime.
Calcium Nitrate Spray
Since irrigation and spraying the tomato leaves have little to minimal effect, you want to irrigate the soil with calcium nitrate. This is a water-soluble form of calcium that’s easily absorbed by the roots. Calcium nitrate acts quicker than carbonate, thus would be a better choice if your tomato plants are already showing signs of calcium deficiency.
Using a gallon of water, dilute approximately four tablespoons of calcium nitrate. Spray on the fruits (again, avoid the leaves) just right before your tomatoes get big as a dime. You may also use this to fertilize the soil around your tomato plants every two weeks.
Calcium Nitrate Side Dressing
This method also utilizes calcium nitrate fertilizers, but instead of spraying on the fruits, the fertilizer is applied in its granular form. Start by applying 1 tablespoon of granular fertilizer per tomato plant, approximately 2 inches away from the stem. Once done, cover it with soil and monitor the growth of your plants.
Calcium for Tomato Plants: Final Thoughts
Calcium plays a crucial role in the development of your tomato plants. It helps prevent blossom end rot and other common problems that may arise during the fruit production process.
If you’re aware that your soil is particularly on the acidic side, perform a soil test and use any of the above-mentioned methods to supplement calcium. It’s best done during the fall, right before transplanting your tomatoes.
This way, your plants will have enough time to absorb the calcium, preventing the occurrence of BER or other problems related to calcium deficiency early on.