How to Fix a Tomato Plant With Too Much Nitrogen

Dig a hole a foot deep into the garden soil next to one of your tomato plants. Collect a soil sample and test it for nitrogen with a soil test kit according to the directions on the packaging. Most kits list nitrogen readings as surplus, sufficient, adequate, deficient or depleted. Results with "surplus" readings mean action must be taken.

Inspect your tomato plants for signs of nitrogen overdose if no test kit is available. Tomato plants express an excess of nitrogen by having lush, dark green leaves but few tomatoes or flowers. Check the tomatoes that are growing for poor or uneven size, shaping or coloration.

Rake over the upper inch of garden soil around your tomatoes without digging down into their roots to loosen the soil. Spread 1 inch of leaf mold mulch over the loose soil. Rake over the bed again to mix the leaf mold mulch in with the soil. The leaf material will decompose faster than bark and reduce some nitrogen levels within weeks.

Spread soft wood-chip mulch over the soil 2 to 3 inches deep. Wood-chip mulch not only protect against weeds, but decreases the nitrogen in the soil as the wood mulch breaks down over a period of months to a year.

Water the soil regularly to supply your tomato plants with an inch of water a week. As your tomatoes take up available water, the excess water can rinse away available nitrogen from the soil.

Prune off excess foliage from the plant as the soil recovers by removing any "suckers" that appear. Suckers look like small branches which can be found growing at a 45-degree angle in the fork between the main stem of the plants and their true branches.

Test the soil again as in Step 1 two months after you spread mulch and started regularly watering to note any decrease in the nitrogen in the soil. Continue watering and using wood-chip mulch as well as retesting the soil as needed until the nitrogen level reads "sufficient" at the highest.