At last, at last! Those long-anticipated tomatoes from your garden are beginning to ripen. And if you, like most people, look forward to enjoying that wonderful flavor, you may be dismayed to find that some of the fruits have imperfections.
While most garden vegetables include some that don't look picture-perfect, here are some explanations for your tomatoes' appearance.
The most common question is about tomatoes that have a brownish, leathery spot on the bottom. While this disorder is called blossom end rot, it is not a disease, but a cultural problem. It happens when the plant roots cannot take up enough calcium to support the tomato's cell walls, especially the ones on the blossom end, and they collapse.
Rarely does this mean that your soil is lacking calcium. Instead, the main cause is setting your plants out when the soil temperature is lower than 65 degrees. This stunts the roots, making them unable to access the calcium. Cold, wet springs make this problem more common. If you don't own one, buy a soil thermometer and use it next spring — air and soil temperatures are vastly different.
A secondary cause of blossom end rot is using the "drought and drown" method of watering. Tomatoes like to be evenly moist, which helps the fruit to develop evenly. If you grow just a few tomatoes, as I do, you might want to try setting a plastic milk jug with a few holes punched in the bottom next to each plant. Fill the jugs with a garden hose, and water will slowly drip out the bottom. When it is hot, and plants are growing and setting fruit, this might need to be done daily, but frequency really depends on your soil and the weather.
Grooves, or tan, callous-like lines in tomatoes is called catfacing, and is caused by incomplete pollenization, or blooming when the weather is too cold. Can't really do much about that.
Sunscald, or sunburn, is the main reason I don't prune leaves from my tomato plants. Sunscald appears as a hard, yellowish patch on the tomato. The sun does not need to touch the tomato in order for it to ripen; in fact, in the Rogue Valley, tomatoes may need protection from the sun; sometimes using shade cloth.
All of the disorders listed above are cosmetic — they do not affect flavor or make the tomato unsafe to eat. Simply trim off the affected part and enjoy your tomato.
If you grow tomatoes in a pot or other container, here are a few suggestions for you. First, select a tomato variety that is intended for container growing; not all are. Research has shown that when grown in the ground in loose, well-drained soil, a tomato plant's roots will go down more than eight feet, so you can see how it would find a container a bit crowded.
Choose a container that will hold a minimum of five gallons of soil mix. Because it cannot extend its roots as far as it normally would, you will need to feed and water it more carefully. Using liquid seaweed, or a micronutrient fertilizer such as Dr. Earth's rather than a balanced NPK, will help supply nutrients that ordinarily would be obtained from garden soil. Tomatoes grown in your garden are light feeders, however, so they probably won't need this special treatment.
Whether you like them in a salad, a sandwich, sliced for lunch, or in the garden with salt shaker in hand, enjoy that wonderful flavor of your homegrown tomatoes.
If you have questions about tomatoes or garden problems, call the Oregon State University Master Gardener plant clinic at 541-776-7371.
Carol Oneal is a past president of the OSU Jackson County Master Gardeners Association. Email her at firstname.lastname@example.org.