Touring the Tomato Greenhouse at HPD

by Mary Ann Sherman
October – November 2018
Leon Hershberger of Cushman Creek Supply in Holton, Mich., conducted the tour of the tomato high tunnel. Additional information and a little good-natured ribbing came from Jay Stutzman, local dealer for ISP Technologies who supplied the plant food.

The tomatoes, peppers, onions, cabbage and broccoli were growing in soil that used to be an alfalfa field. That gave them a bit of a nitrogen push. Having grown tomatoes and peppers himself, Leon said that fertilizer is very important, but management is the big thing. ISP tries to help and guide the grower with both fertilizer and management.

The best size for seedlings is 6 to 8 inches. At 18 inches, they’re too tall. Even if they’re starting to set fruit, you’ll lose it.

The ventilation system had failed twice, resulting in the loss of two fruit sets. The temperature hit 124 degrees and “toasted the flowers.” We could see where the tomatoes should have been.

tomato greenhouse at horse progress days
The tomato greenhouse at Horse Progress Days.

At the other end of the spectrum, you need nighttime temperatures above 60 to 65 degrees. Early morning temperatures of 50 degrees could cost you a fruit set.

It’s easy to grow beautiful plants, but the fruit determines the paycheck. At the end of June, the wholesale price for tomatoes at the Clare County Produce Auction ranged from $1.70 to $2.00 per pound.

Someone added a few hanging baskets of flowers for a touch of color. They weren’t really needed because the dark green plants and the bright red tomatoes were beautiful all by themselves. The plants looked so good because two fruit sets were missing.

Producing fruit stresses the plant. When the fruit starts to ripen, fertility needs “start peaking out,” as Leon put it. The plants start to pull nutrients from the older leaves at the bottom. As you take fruit from the bottom of the plant, you get more growth at the top.

 “You can see how your season will progress from the bottom up,” Leon said.

Balancing nitrogen and trace minerals is important to get a good fruit set. Some people thin the fruit to only four tomatoes. This depends on the size of fruit that you want. If the fruits vary in size, you likely need potassium, phosphorous and calcium.

If you see pale yellow on the leaves, you need magnesium. Those yellow patches provide an ideal place for disease like blight to set in. Brown mold on the underside of the leaves also indicates magnesium deficiency. Leon advised the audience that Epsom salts are an inefficient way of boosting magnesium. For foliar feeding, mist over the tops of the plants. To treat disease, wet the leaves well.

Leon strongly recommended a soil test every fall. Not all fertilizer can go through the drip line. Figure on using some dry as well. You want to get all the nutrients you can out of the soil.

Unfortunately, the ornamentals brought in more than bright colors. They brought in aphids as well. That meant treating the row of peppers with silica. The best money comes from specialty early greenhouse tomatoes that have plenty of flavor. If the nutrients are there, you’ll have good taste and good shelf life. You want to establish a market so that when the glut comes, any customer who leaves you will be disappointed with the poorer quality of your competition.

Moving outside, we discovered thrips in the onions. To drive them out would require plenty of water and high pressure.

For early organic cabbage, Bt (bacillus thuringiensis) works well against loopers. If your cabbage leaves are bumpy, it could well be a shortage of calcium and boron.

We got to sample a beautiful head of broccoli. It was crisp, crunchy and flavorful. When broccoli tastes that good, who needs dip?

Leon reminded us that nitrogen makes plant growth but tastes bad. Trace minerals make fruit and flavor. You need the proper balance between nitrogen and minerals. A mushy cantaloupe is the result of too much nitrogen.

Perhaps the most memorable line was his warning that, “Chicken manure can do a great job in ruining flavor”. rh house logo
Mary Ann Sherman lives in Ohio and reports on the Workshops and Seminars at Horse Progress Days each year. This article appeared in the October/November 2018 issue of Rural Heritage magazine.

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