There’s no question that for many gardeners, last summer’s tomato crop left a lot to be desired. Even those of us who had plants loaded with fruit wound up disappointed as the first killing frost of the fall arrived before the majority of fruit had ripened. With our current spring weather resembling last year’s unseasonably cold and wet growing season, here’s some time tested tips to get tomatoes to produce and ripen — even when heat is lacking.

First, choose the right variety. WSU Master Gardener Emeritus Cindy Knight has conducted exhaustive tomato research trials at her home in Elma for over 30 years to determine which varieties will do well in our cool, cloudy, coastal climate. According to Cindy, “Big Beef” has performed well in the large tomato category. For salad tomatoes, “Early Girl” and “Early Cascade” are recommended. “Sugar Lump,” “Sweet Million” and “Yellow Pear” are the favored cherry tomato varieties. For paste tomatoes both “San Marzano” and “Roma” have done well, and for a tasty yellow tomato, try “Lemon Boy.”

Oregon State University has also introduced a number of tomato varieties that set fruit well under our cool coastal climate. They include: “Legend,” which is resitant to the late blight fungus; “Willamette,” which was the standard in Western Oregon for 15 years; “Oregon 11,” which in Oregon produces the first ripe fruit in early July; “Gold Nugget,” a golden cherry tomato; “Santiam,” which produces fruit up to 3.5 inches in diameter; “Saucy,” an early paste tomato; “Oregon Spring,” which produces incredibly early yields of 4-inch oval tomatoes; and “Siletz,” which is similar to Oregon Spring but with larger fruit and better flavor.

Second, when planting tomatoes, set plants deeper in the soil than they came in the pot. Tomatoes are unique since they are able to develop roots all along their stems. You can either dig the planting hole deeper, or dig a long, shallow trench, remove the lower leaves, and lay the stem down in the trench and cover with soil. Gently bend the top of the plant so the tip leaves are above the soil level. Roots will grow along the stem, providing a better root system early in the year.

Third, mulch the plants with a red plastic mulch. Now available in most retail nurseries and garden stores, the benefit of using red mulch is that it reflects the far-right part of the light spectrum onto the tomato plant foliage. This in turn increases the production of the plant’s phytochromes which are color sensitive proteins that regulate plant growth and development. Researchers at the U.S. Department of Agriculture and Clemson University found that using red plastic mulch not only resulted in increased tomato yields, but also earlier harvest. 

Fourth, increase the temperature of the micro-climate around your plants by using a floating row cover or water tubes. The advantage of water filled tubes, which are commonly sold as “Walls of Water” is that they collect heat during the day, releasing it at night. You can make your own inexpensive walls of water simply by filling used one-gallon milk jugs or two-liter soda pop bottles with water and completely circling your plants with them. Be sure to remove the water tubes before the plant becomes crowded inside.

Finally, there’s no hard and fast rule about leaving or taking off suckers from tomatoes. Many of the most popular tomato plants grown today are what are referred to as determinate or upright bushtype plants that need very little staking, pruning or sucker removal. If you grow some of the older indeterminate varieties like “Early Girl,” however, you may want to pinch out some of the suckers that originate between the main stem and main branch. Removing all of the suckers could potentially result in sunburn to the fruit, so leave a few!

All too frequently the home vegetable gardener will trim leaves from tomato and other vegetable plants, hoping that the fruit will ripen better if exposed to a greater amount of sunlight. Sufficient foliage must be present for photosynthesis to continue at the required rate. If the essential “food” is not manufactured as needed, normal fruit production will not exist. Cutting away an excessive amount of foliage destroys the process that produces the fruit. Removing a few leaves would be okay — just don’t overdo it!

Remember to water plants on a regular basis making sure to wet soil to a depth of eight inches. Irregular watering leads to blossom end rot and cracking of the fruit.

Do we need to purchase more than one tomato variety to ensure good pollination? 

No! Tomato flowers come complete with both male and female organs and are self-fertilizing. Pollen is shed with great abundance between 10 a.m. and 4 p.m., on dry, sunny days. Normally, the wind will pollinate the flowers sufficiently. To ensure better pollination, gently shake or vibrate the entire tomato plant. The best time to do this is mid-day when it’s warm, and the humidity is low.

Optimum fruit set occurs within a very narrow night temperature range of between 60° to 70°F. When tomato plants experience night temperatures lower than 55°F or above 75°F, interference with the growth of pollen tubes prevents normal fertilization. The pollen may even become sterile, thus causing the blossoms to drop. High daytime temperatures, rain, or prolonged humid conditions also hamper good fruit set.


EDITOR’S NOTE: For answers to local gardening questions go to www.pnwmg.org or call 360-249-4125, the WSU Extension office in Elma, or call Rachel Gana at 642-8723 or acornwp@yahoo.com.

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