Applying Calcium Nitrate For Tomato Blossom End Rot

By Darcy Larum, Landscape Designer

It’s midsummer, your flower beds are blooming beautifully and you’ve got your first little vegetables forming in your garden. Everything seems like smooth sailing, until you see mushy brown spots on the bottom of your tomatoes. Blossom end rot on tomatoes can be extremely frustrating and once it has developed, there’s not a lot that can be done, except to patiently wait and hope that the matter will cure itself as the season progresses. However, using calcium nitrate for tomato blossom end rot is a preventative measure you can do early in the season. Continue reading to learn about treating blossom end rot with calcium nitrate.

Blossom End Rot and Calcium

Blossom end rot (BER) on tomatoes is caused by a deficiency of calcium. Calcium is necessary for plants because it produces strong cell walls and membranes. When a plant does not get the amount of calcium needed to fully produce, you end up with malformed fruit and mushy lesions on fruit. BER can affect peppers, squash, eggplant, melons, apples and other fruits and vegetables, too.

Oftentimes, blossom end rot on tomatoes or other plants happen in seasons with extreme weather fluctuations. Inconsistent watering is also a common cause. Many times, the soil will have adequate calcium in it, but because of inconsistencies in watering and weather, the plant is not able to take up the calcium properly. This is where patience and hope comes in. While you can’t adjust the weather, you can adjust your watering habits.

Using Calcium Nitrate Spray for Tomatoes

Calcium nitrate is water soluble and is often put right into the drip irrigation systems of large tomato producers, so it can be fed right to the root zone of plants. Calcium only travels up from plant roots in the plant’s xylem; it does not move downward from the foliage in the plant’s phloem, so foliar sprays are not an effective way of delivering calcium to the plants, although calcium rich fertilizer watered into the soil is a better bet.

Also, once fruit has grown ½ to 1 inch large, it is unable to absorb anymore calcium. Calcium nitrate for tomato blossom end rot is only effective when applied to the root zone, while the plant is in its flowering stage.

Calcium nitrate spray for tomatoes is applied at a rate of 1.59 kg. per 100 feet of tomato plants or 340 grams per plant by tomato producers. For the home gardener, you can mix 4 tablespoons per gallon of water and apply this directly to the root zone.

Some fertilizers that are made specifically for tomatoes and vegetables will already contain calcium nitrate. Always read product labels and instructions because too much of a good thing can be bad.

More Information about Soil, Fixes & Fertilizers
<<PREVIOUS3 2 1 ... 12NEXT>>
Print This Article
This article was last updated on
Did you find this helpful?
Share it with your friends!

Additional Help & Information

Didn't find the answer to your question? Ask one of our friendly gardening experts.

Do you know anything about gardening? Help answer someone's gardening question.

Read more articles about Soil, Fixes & Fertilizers.

Search for more information

Use the search box below to find more gardening information on Gardening Know How: