Tips for keeping your tomato plants thriving

A delicious tomato is the goal of many gardeners, new and old alike. Whether you’re growing tomatoes in pots on patios or in a garden, there must be ample space and proper light. An intrepid gardener in the desert needs to devise creative ways to get and keep tomatoes producing despite the dry air, the blistering sunlight and elevated temperatures — the usual challenges that the Mojave sends our way.

Tomatoes are both a fruit and a vegetable. Although that might be interesting to horticulturists, a more important piece of information is that tomatoes and excruciatingly hot weather do not mix well.

When temperatures reach the triple digits, tomatoes suffer. If they have not yet reached the ripening point, they might become bleached to an unsightly yellow green and never ripen. Many people find that smaller tomatoes have the best chance, since they reach full size and ripen before temperatures get too high. Beefsteak types are not usually a great choice.

Midspring is a good time to get tomato transplants into the garden, raised bed or patio. Starting them from seed would need to have been done, indoors, back in February.

The intrepid gardener has a couple of goals with tomatoes. The first is to prevent blossom-end rot.

Tomatoes are moderately forgiving plants and will usually bounce back even if the soil becomes slightly dry. What is frequently damaged when plants become even slightly dry is the fruit itself.

One gloomy sight on the plant is a fruit that looks lovely and ripe, except that the bottom is black or brown and hard. This “blossom-end rot” happens just as the fruit starts to form.

It is a sad story. As the fruit began to take shape, there was a little shortfall of water getting to it. Calcium is critical for tomato production. Because of a lack of water, insufficient calcium got to the site. It would not need to be a severe water deficit, just enough to affect the first cells formed in the fruit.

After the plant received enough water, the fruit grew properly, so the rest of it looked fine, but not that earliest part, closest to where the flower was.

To reduce the likelihood of blossom-end rot, grow a heat-tolerant variety. This will have the best chance of success. Never let the plants get dry, especially once they have produced their flowers. That might be easier said than done, but it is worth a try.

If you do get blossom-end rot, don’t lose heart. Unless the plants were allowed to dry out frequently, only one or two become damaged on a whole plant. Unsightly, but the fruit is still edible. When the blossom end is removed, the tomato tastes perfect.

Tomatoes are definitely “warm season” vegetables, meaning they do not respond well to being chilled, but they cannot thrive in the peak of desert summer. Most tomatoes’ growth slows when the temperature gets much above 85 degrees for any length of time. The young fruits can crack, or even be destroyed, when they are exposed to our full summer sunlight for extended periods. A sun-bleached tomato is not a pretty sight.

Because of our weather challenges, another important garden goal is to prolong the growing period. In other parts of the country, “extending the growing season” means planting things earlier, protected from cold. In the desert, it means stretching the growth period into the summer. This calls for some manipulation of the environment around plants, but it sounds more intimidating than it is.

Adding compost and a cooling layer of mulch is the first step. Shading the growing spot by using a high tent of “floating row cover” can be effective at keeping the most intense sun from scorching the tomatoes.

Selecting a heat-tolerant variety is important; many of these are less than 2 inches in diameter. Cherry tomatoes also grow and produce well.

For several reasons, I am planting my tomatoes in large pots this year. They will dry out faster than if they were in the ground, but as the weather gets hotter, I will be able to move the pots out of the most direct sun. I try to make sure that pots are on wheels.

Come the end of June, I will cut down my tomato (and pepper) plants to about 3 or 4 inches. I will keep the soil moist and make sure the mulch is in place. When the weather cools a bit, the plants will produce again and continue to do so until nighttime temperatures fall into the 40s.

At the Cooperative Extension office, we have fact sheets on growing tomatoes and dealing with some of the problems. These are available through the Master Gardener help line, or visit http://bit.ly/1G1crxv.

Angela O’Callaghan is the social horticulture specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.