According to the Eastern North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs, Summer is one of the three optimal vegetable growing seasons in coastal North Carolina. Warm season vegetables that were transplanted in mid-April are progressing through their life cycles becoming mature plants with blossoms that will eventually develop into a harvestable food crop.

There are several times during a vegetable plant’s life cycle that it is recommended to fertilize. A soil test facilitated through the local Cooperative Extension Office is the most accurate way to determine when and how much fertilizer to apply.

Soil Sample Pick-Up; Drop-Off

Fertilizing while the plants are seedlings or at the time of transplanting is initially recommended. Once vegetables have grown to a healthy size, hold back any further fertilizing until the plant sets fruit. Do not fertilize vegetable plants when it is actively flowering, as it may slow fruit production and cause excessive growth. At the time fruit is forming, additional fertilizer can be added to individual plants or side dressed down rows.

To some people, using pre-mixed fertilizer products, referred to as “plant food”, from box stores is a no-brainer. These products offer a level of convenience and simplicity suited for novice gardeners and are often a more economical choice. Plant food can be a quick and easy solution to fertilizing, oftentimes making for a successful gardening season. But pre-mixed fertilizers can do more long-term harm to vegetable gardens despite the boost in plant growth it gives. The use of these products in vegetable gardens can be detrimental to soil fertility. These products stifle naturally occurring soil microbes through the water-soluble fertilizers that have a high salt content.

The high salt content of synthetic fertilizers destroys the living, breathing organisms in the soil that is crucial for healthy plants. These products supply a large amount of readily-available nitrogen that is derived from synthetic ammonium. Ammonium is a good thing but too much of it can be extremely detrimental to vegetable gardens, especially to tomato plants.

Blossom end rot on maturing fruit | Brenda Kennedy | University of Kentucky

Too much nitrogen can not only decrease tomato plant yields and burn its foliar tissue, but it can also introduce diseases such as Blossom-End Rot. The disease starts small at first with a small, dark, water-logged, circular area appearing at the bottom of the fruit. As the disease progresses, the entire bottom half of the fruit develops these characteristics, making it un-harvestable and inedible. To avoid this nasty disease in tomatoes and other vegetables this year, avoid using synthetic fertilizers that are high in ammonium nitrate. Instead of using pre-mixed fertilizers or plant food this year, consider conducting a soil test because soil fertility is not one size fits all!

Resources

• University of Georgia Extension:
  • Georgia Homegrown Tomatoes
  • Blossom-end Rot Even Uglier Than Name
• Yara: Role of Nitrogen in Tomato Production