Are Tomatoes Easy to Grow in the Rogue Valley?

Homegrown tomatoes, home grown tomatoes,
Wha’d life be without homegrown tomatoes?
Only two things money can’t buy,
That’s true love and homegrown tomatoes.

 – John Denver, “Home Grown Tomatoes,” 1988

If you are a gardener in the Rogue Valley, growing at least one, if not a dozen, tomato plants every summer is practically a requirement in order to claim “real” gardener status. During the first weekend of every May, throngs of tomato enthusiasts leave the Spring Garden Fair at the Jackson County Expo with tomato plants of all types and sizes.

We eagerly anticipate that fine summer day when we will walk into our garden and pluck from the vine the prettiest, juiciest red, yellow, orange or purple tomato the world has ever known. If it’s a cherry tomato, we may pop one or two in our mouths before we even leave the garden. If it’s a meaty beefsteak tomato, we’ll carry it proudly into the kitchen and make that colorful hallmark of the season – the summer salad.

However, in between lugging tomato plants home from the garden fair and lugging our bounty into the kitchen, all kinds of unexpected things can happen. After eight years of growing tomatoes in the Rogue Valley, my answer to whether tomatoes are easy to grow here is “it depends.”

On one hand, if you set out a tomato plant in a sunny spot with reasonably fertile soil and water it regularly, you are going to end up with some tomatoes. On the other hand, if you are a “serious” tomato gardener and expect no less than the finest in terms of tomato quantity and quality, achieving that lofty goal is somewhat more difficult.

There are two big challenges to growing tomatoes in the Rogue Valley, and they both have to do with temperature. It’s well to remember that tomatoes originated in the tropical climes of western South America. Even after thousands of years of cultivation, it remains true to a certain extent that you can take tomatoes out of the tropics, but you can’t take the tropics out of tomatoes.

Accordingly, one challenge Rogue Valley tomato gardeners face is the dramatic temperature fluctuations between night and day, and from day to day, in the springtime when tomatoes prefer consistent temperatures to establish their roots, set flowers, and produce fruit.

For example, in May the temperature soared to almost 90 degrees on the 11th, but nighttime temperatures dropped to 50 degrees – that’s a 40-degree fluctuation! – and tomato plants don’t like temps below 55 degrees. Then on May 14th, the high daytime temperature didn’t reach 65 – that’s a 25-degree shift in a matter of three days!

These fluctuations confuse tomato blossoms, which shows up in the fruit the flowers set because tomatoes, like cucumbers, squash, eggplants and peppers, are produced from the flower’s ovary. If a tomato flower becomes deformed or is otherwise compromised due to cold temperatures (below 55 degrees), hot temperatures (above 95 degrees) or extreme weather shifts, the fruit will also be deformed or compromised.

The second challenge tomato gardeners encounter is the dry, intense summer heat in our area that is increasingly becoming the ominous harbinger of wildfires and smoky gardening days. Tomato plants will stop setting flowers/fruit and will drop flowers, and tomatoes are slower to ripen if temperatures exceed 95 degrees, particularly for several days in a row. It’s not only the intense heat that bothers tomatoes; it’s the lack of moisture in the heat that causes tomato plants to shut down.

Last year, 19 days in July exceeded 95 degrees (but only six days in August exceeded 95 degrees because smoky haze kept the temperatures down). I have talked with several gardeners who told me last year was the worst year they can remember for tomato harvests, and my tomato crops suffered, too.

Most of the other problems tomato plants develop are secondary effects of these temperature issues. Stressed tomato plants that have switched into survival mode are less able to fight against insect pests that are common tomato invaders: aphids, flea beetles, fruitworms, hornworms, cutworms, whiteflies and spider mites.

Weakened tomato plants also have fewer defenses against common tomato diseases: curly top virus, early and light blight, verticillium wilt and tobacco mosaic virus. Cornell University’s Vegetable MD Online website has useful descriptions and images of each of these diseases, as well as other common problems with growing tomatoes.

Fungal diseases are one of the most common tomato diseases, caused by foliage coming into contact with the soil, or water splashing from the soil to the leaves by using sprinklers or a forceful stream of water from a hose nozzle.

In addition to insect pests and diseases, tomato crops can develop physiological disorders such as cracking, zippering, catfacing, sunscald and blossom end rot. These disorders cause tomatoes to develop uneven coloration or deformities (sometimes the deformity looks like a cat’s face). The good news about physiological disorders is that the damaged portions of the tomato can be cut off and the fruit can still be eaten. So much for growing the prettiest tomatoes the world has ever known, though.

Blossom end rot, where tomatoes develop brown or black lesions on the blossom end of the fruit, is a particularly common problem. Although the disorder is caused by a calcium deficiency, it’s often the case that it’s not a matter of the soil having the deficiency, but that the tomato plant is unable to adequately take up calcium from the soil because it’s stressed and/or because of fluctuating soil moisture.

Over-fertilizing or using the wrong kind of fertilizer can also cause nutrient imbalances (use fertilizer high in phosphorus and low in nitrogen). In addition, fertilizer will damage leaves and fruit if it’s splashed onto them during fertilizing.

Uneven soil moisture is sometimes due to poor soil drainage (soil with lots of clay), but most of the time it’s because automatic drip systems don’t accommodate for fluctuating air temperatures. On hot days, gardeners tend to let the soil dry out too much, and then try to overcompensate by watering too much.

The trick is to supplement drip systems with careful hand watering on the hottest days, and to scale back on watering if needed when temperatures drop. Testing the soil frequently by poking your index finger into the soil to the second knuckle, or using a good moisture meter, is the best way to determine if your tomato plants need more or less water.

Mulching your tomato plants will help keep moisture levels consistent, and will protect plant roots from drying out. Having floating row cover ready to protect tomato plants on the hottest days and coolest nights will also help prevent fruiting failures.

Perhaps the best way to promote success with tomato gardening is to use varieties that have been developed for the growing conditions in our area. Oregon State University’s vegetable breeding program has developed several tomato varieties in the past 40 years including: Medford, Talent, Indigo Rose, Legend, Gold Nugget, Oroma, Oregon Spring, Oregon Star, Santiam and Siletz. Find out more about these Oregon-bred tomatoes at the OSU Extension Service website: https://extension.oregonstate.edu/news/eight-osu-developed-tomatoes-try

If a tomato plant produces well in your garden, be sure to save some of the seeds from the fruit for next season. As offspring from plants that have thrived in the particular microclimate of your garden, these seeds will likely grow into healthy, highly productive tomato plants, too.

Even if growing the perfect tomato isn’t all that easy in the Rogue Valley, don’t allow the challenges keep you from trying. After all, as John Denver sang:

Plant ’em in the spring eat ’em in the summer,
All winter without ’em’s a culinary bummer;
I forget all about the sweatin’ & diggin’
Everytime I go out and pick me a big’un. 

Homegrown tomatoes home grown tomatoes,
Wha’d life be without homegrown tomatoes?
Only two things money can’t buy,
That’s true love and homegrown tomatoes.

For more about tomatoes and tomato gardening, visit

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