I’ve added too much nitrogen to my garden this year as is evident by lush plants but small or no fruit on my yellow squash and pole beans. Is there a practical, organic way to counteract this mistake? Should I simply let time pass, conduct a soil sample, and start over?
Nature’s plan for removing excess nitrogen is to harness the hunger of plants, and squash is often used as a “mop-up” crop in soil that is holding high levels of nitrogen. After a few weeks, your squash may exhaust the nitrogen supply and produce a good crop, so you may want to wait to see what happens.
Your beans’ prognosis is less promising because beans remove little nitrogen from the soil. With abundant nitrogen to fuel rampant growth of the vines, they are likely to produce a small crop very late in the season, and the soil will still be holding excess nitrogen. To set things right, put heavy feeding crops like cabbage, broccoli or spinach to work in the fall, or mulch over the site through winter, and plant it with sweet corn next year.
As for emergency measures, gypsum is sometimes suggested as a cure for this problem, but research shows that it has no special talents for dissolving nitrates and other salts. As a last-ditch effort, you can try root-pruning the plants by pushing a spade into the ground at a couple of points within each plant’s root zone – a trick used in flower gardening that sometimes shocks overfed plants into initiating blooms.
Working with organic fertilizers can be confusing, because they release nutrients slowly in cold soil, which makes gardeners think their plants need more fertilizer. Then, when warming soil makes many more nutrients available, you find that you have overfed your plants. Oftentimes, grass clippings mixed into the soil provide all the nitrogen that vegetables require. In the future, you might try using only liquid organic fertilizers (such as those made from fish and seaweed) to start off beans and other legumes. When fertilizing other crops, take care never to exceed the application rates given on the package.
Check out these articles to learn more about simple, cheap or free garden fertilizers:
A Better Way to Fertilize Your Garden
Build Better Soil with Free Organic Fertilizer
Photos of filet beans, left, and zucchini, right, by Barbara Pleasant.
Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.