Growing Delicious Sweet Corn & Tomatoes

by Jan Cashman

We enjoy all the vegetables in our garden, but we especially love the sweet corn and tomatoes we grow.  In August we gorge ourselves on BLT’s with sweet corn, a meal we eat every day we can when the corn and tomatoes are ripe.  Those who live in Iowa might say we don’t have the climate for either corn or tomatoes, but most of us Montana gardeners know we can grow these warm season crops here.

There are a few tricks to successfully grow sweet corn and tomatoes in our climate.   First, plant early varieties.  Plant 60 to 70 day sweet corn. Tomatoes are most likely to ripen if they are less than 70 days to maturity.

Sweet corn varieties can be confusing.  In the past, early sweet corn hybrids like Earlivee and Early Sunglow were all we had to choose from.   Today, more tender sweet corn hybrids have been developed that retain their sugar for a longer time after they are picked.   There are several sugar enhanced (se) hybrids that ripen early and do not have to be isolated like the supersweet (sh2) varieties.  We have grown and enjoyed Kandy Kwik (68 days) and the bicolor, Quickie (64 days).   Trinity bicolor (68 days), Precocious (66 days) are other sugar enhanced corns with cool soil vigor.  ‘Cool soil vigor’ is an important trait to look for in sweet corn seed for our area.  If you want to save your corn seed for next year, you’ll need to plant an open-pollinated variety like Golden Bantam.  Open-pollinated sweet corn will need to be isolated or it will cross with other varieties.

In the past, gardeners here planted mainly Early Girl and Fantastic tomatoes.  Today, there are many tomato varieties-cherry, grape, paste, small, large, yellow, orange, new and improved that are early and sweet.  Tomato plants fall into two general categories: determinate plants which quit growing, then the fruit ripens all once, and indeterminate plants which keep growing, need support, and pinching back in mid-summer so the fruits set instead of growing more vines.  In our informal taste tests on tomatoes, the cherry types were usually chosen as the sweetest; the yellow cherry Sunsugar was as sweet as candy.  Small, potato-leaf Stupice from Czechoslovakia, and medium-sized Celebrity did well in our taste tests.  Small Northern Delight and large Park’s Whopper have produced well in our garden.

Sweet corn and tomatoes should be planted into warm soils—at least 60 to 65 degrees.  In our garden,  we wait till the end of May to direct sow sweet corn and set out tomato plants.   Experience will tell you when your soils have warmed enough to plant corn and tomatoes—or invest in a soil thermometer.  Remember to pinch off the lower leaves of your tomato plants and plant them deeply—new roots will form on the buried stem.

John Austin, from the Gallatin Gardeners Club, an extraordinary gardener who has produced ripe  tomatoes here in early July, warms the ground where he is going to plant his tomatoes by digging the hole for them and laying down red mulch film.  When he is ready to plant, he cuts a hole in the film for the tomato plant.  This red film also reflects far-red light wavelengths up into your tomato to stimulate growth, and helps control weeds and keeps the soil from drying out.

‘Walls-o-Waters’ extend the season on tomatoes. These green tubes of water protect your tomatoes from frost and provide a greenhouse effect for the new plants.  (We use a small tomato cage inside the Wall-o-Water to support it.)  The water in the tubes warms up during the day and continues to warm your tomato plants at night.  The directions recommend setting them up in your garden about a week before you plant, to warm your soil.    You can leave the Walls-o-water on all summer but we usually take ours off in late June.

Sweet corn and tomatoes need different fertilizers.  Sweet corn needs nitrogen.  When I switched from a well-balanced fertilizer to one higher in nitrogen, my corn did better.  Tomato plants, on the other hand, grow many leaves and little fruit if your fertilizer is too high in nitrogen.  For tomatoes, use a fertilizer which has less nitrogen and more phosphorus.

Tomatoes can develop ‘blossom end rot,’ a disease where the blossom end of the tomato turns black and leathery because the roots are not taking up enough water and calcium.  A sudden period of drought can cause blossom end rot.   Watering evenly is important—don’t let your plants get too dry.  And, wait to plant your tomatoes till the soils have warmed so the root systems develop properly.   Also, be careful not to damage the root system by cultivating too close to it.  Some varieties of tomatoes are more susceptible than others to blossom end rot.

If you think a meal of BLT’s made with fresh tomatoes along with home-grown sweet corn sounds good, plant sweet corn and tomatoes and enjoy the fruits of your labor next August.