Garden Q&A: Lush plant produces no tomatoes
Q: My tomato plants last year were big and beautiful but did not bloom or put out fruit. Why? They looked so good.
A: Nearly every time I hear about a plant with a whole lot of green and very little fruit, I blame it on the soil (and then on the gardener — sorry!). This type of excessive plant growth, coupled with limited flower and fruit production, is a sure sign of a nutritional issue.
There are three primary macronutrients a plant uses to grow: nitrogen, phosphorus and potassium (known as N-P-K). These are called macronutrients because they are needed in the greatest amount to support plant growth. They are no less important to growth than, say, boron or magnesium; they are just the ones that we need to pay more attention to as they are needed in more substantial quantities.
Each of these nutrients performs different functions within a plant (you’ll see where I’m going with this in a second, I promise!). In a nutshell, the nitrogen is responsible for making new, green growth; the phosphorus supports a good root system and helps develop fruits and flowers, and potassium raises plant vigor and helps make them tough and hardy.
When a plant, such as your tomato, makes a lot of green and no fruits or flowers, it usually means there is too much nitrogen in the soil and, perhaps, not enough phosphorus. I’m thinking that you may have fertilized with a high nitrogen product or manure within the past year or two and the nitrogen needs to be balanced out. The only way you’ll know how to do that is to contact your local county office of the Penn State Extension Service and have a soil test done. It won’t cost you very much but will tell you a great amount of information about your soil.
The results of that test will inform you of any nutritional imbalances in the soil. If there isn’t enough phosphorus in your garden, the test will recommend you add some. To do this organically, you can top-dress with bonemeal or another phosphorus-rich fertilizer. That being said, you should never automatically add this, or any other fertilizer, without getting a soil test first because you can wind up adding too much of a good thing and tipping the scales in the other direction.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.
Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.