Nitrogen is an important plant nutrient in the metabolism of vegetable crops. It also is the nutrient most often lacking soils, so additional nitrogen must be supplied to achieve good yields.

Most vegetable crops are fast growing plants with lush vegetation and high nitrogen requirement. With the extreme mobility of nitrogen in the soil, it is necessary to split applications of the nutrient on most vegetable crops into a pre-planting application and one or two post-planting fertilizations known as “side dressings.”

Most home vegetable gardeners should apply a pre-plant application of 1/2 to 1 pound of nitrogen per 100 feet of row, usually applied with a complete fertilizer such as 2 -3 pounds of 13-13-13, 4-7 pounds of

8-8-8 or 4-5 pounds of 8-24-24 per

100 feet of row depending on the vegetable crop. The application before planting usually provides enough nitrogen to achieve good early plant growth through the flowering stage.

Side dressing will provide enough nitrogen for adequate vegetative growth and good yields for the plant after the flowering stage. Side dressing is achieved

by applying another application

of fertilizer near the base of the plant roots. Be sure not to disturb the roots too much when applying the fertilizer

near the base of the plant. If

possible cover the fertilizer with

a light layer of soil to prevent

the fertilizer from being washed away.

One or two applications of 1/2 to 1 pound of nitrogen per 100 feet of row at the appropriate stage of

plant development is recommended as a side dress to obtain optimal yields. These nitrogen amounts

can easily be obtained by re-applying the pounds of 8-8-8, 8-24-24 or

13-13-13. Appropriate stage(s) of the plant development for side dressing applications on popular Louisiana vegetables are:

• Bell Peppers and Eggplants – at first fruit set.

• Tomatoes (two side dressings) – at first fruit set and at every 3-4 weeks thereafter

• Cucumbers, cantaloupes, watermelons and squash – when vines begin to run and then every 3-4 weeks thereafter.

• Okra – at first fruit set and every 4-6 weeks thereafter.

• Sweet Corn – when corn is 1 foot tall and high and again when it is 3 feet tall.

Sweet potatoes, southern peas, green beans and butter beans should not be side dressed since these plants can produce their own nitrogen – they belong to the legume family. Additional nitrogen will stimulate the vegetative stage of the plant and reduce yields.

To obtain the maximum benefit from the nitrogen side dressing, moisture is needed within two or three days after application. Growers should try to time side dressings with natural rainfall or plan to irrigate soon after the nitrogen is applied.

With irrigation, additional side dressings after harvest on multi-

harvest crops (bell peppers, okra and eggplants) will often increase yields and prolong harvest. These plants, if kept in good condition, can be carried over into the fall and will continue producing until the frost.

For more information go to the LSU Ag Center website, lsuagcenter.com, and copy the Louisiana Vegetable Planting Guide.

For further information or if you have questions, contact David Pichon, county agent – St. Charles/St. John parishes at dpi

chon@agctr.lsu.edu or by phone at 985-785-4473.

David Pichon is a County Agent with the LSU Ag Center. He assists homeowners in St. Charles and St. John Parishes with their Home Gardens and Home Grounds. You can contact him by phone at 985-785-4473 or by e-mail at: dpichon@

agcenter.lsu.edu.