Preventing Blossom End Rot

A nuisance that most gardeners will have the displeasure of encountering during their cultivating career; Blossom End Rot appears as a blackened rot or decay on the bottom (blossom end) of fruits and often occurs during or after periods of extreme dry weather. This physiological disorder is caused by a calcium deficiency and occurs most commonly in tomatoes, but it is also known to effect peppers, eggplant and squashes. Blossom End Rot is unsightly and affected fruits should be discarded or composted.

Tomato EndRot
Blossom End Rot 1

Caused by a calcium deficiency, this disorder has little to do with the nutrients available in the soil, but rather with the plant’s ability to move and utilize the nutrient. Often, the soil contains adequate available calcium, but the plant’s vascular system has been inhibited and it cannot properly move the necessary nutrients. Because plants require moisture to move nutrients, improper watering is most often the cause behind blossom end rot. Other factors that can influence the plant’s ability to use calcium include incorrect fertilization, physical damage to the roots and soil pH.

Because there is no way to stop rot on an individual fruit once it has begun, it is important to take steps to prevent Blossom End Rot from destroying your yields.

  • Maintain consistent soil moisture

It is crucial to provide consistent moisture throughout the growing season as periods of drought or overwatering can restrict the movement of calcium within the plant’s tissue. Remember to water deep (at least 6 inches) to drive the moisture down to the deepest roots. Consider applying mulch to help retain moisture and reduce evaporation.

  • Fertilize Correctly

Avoid using fertilizers with high levels of nitrogen as this restricts the plant’s ability to properly develop fruit. We recommend using a fertilizer specifically formulated for tomatoes and applying according to the directions.

  • Do not disturb roots

Take care to not disturb the roots of the plant while weeding or cultivating. Carefully pluck nearby weeds while they are young. Even a minor disturbance of soil can affect the plant’s root system and lead to disorder/disease.

  • Maintain a soil pH at or around 6.5

Because soil acidity can also effect the plant’s ability to utilize nutrients, we recommend taking a soil test when prepping your garden for planting and adjust the pH as needed.