Horticulture: November 2001

Since 1996, I've been promoting the hoop house growing system as a means by which market gardeners can reduce weather-related risks and extend the growing season. The system has been tried and proven to be effective not only at the Noble Foundation, but by thousands of growers worldwide. While the system works well, there is still room for improvement.

Noble Foundation hoop house tomato crop in late April. Photo: Steve Upson

At the Noble Foundation we are continually seeking ways to improve the hoop house growing system. Our plan to refine the system involves a three-fold approach. First, we work to improve the design of the houses in an effort to make them more efficient. Second, we work to develop new cultural techniques and tweak traditional cultural practices that are compatible with and complement hoop house production. Third, we work to identify the best-adapted vegetable, floral and fruit varieties for hoop house production.

Several years ago we developed a hoop house tomato budget based on the performance of the variety Celebrity. (see PDF file) Celebrity is an All-American selection that is popular with both market and hobby gardeners. It is a high quality, high yielding variety with exceptional flavor.

Celebrity, however, is not an early maturing variety. The ideal hoop house variety is one that fruits early in order to take full advantage of the growth-enhancing characteristic common to all hoop houses.

Early maturing tomato varieties are not without their problems. Because they receive less total energy (sunshine) compared to main season varieties, early varieties tend to produce smaller fruit and less total yield.

Tomato breeders have made progress recently developing early maturing varieties with more favorable yield characteristics. This past spring several of these promising varieties were included in a hoop house trial in hopes of identifying a more perfect hoop house tomato.

On March 22, 2001, transplants of six early fruiting tomato varieties were set into four 40-inch wide beds equipped with drip irrigation and black plastic mulch. Celebrity was included as a standard. Plants were spaced 24 inches apart in the row with one row per bed. Sixteen plants of each variety were used, for a total of 112 plants. Varieties were placed randomly within the house. Preplant fertilizer was applied according to soil test results. Nitrogen was applied weekly based on a schedule developed at the University of Florida. Plants were supported by 15-inch diameter by 5-foot high wire cages. Plants remained unpruned until late in the study at which time they were sheared to maintain pathways between beds.

Harvest began on June 6 and concluded on July 20, by which time yield had diminished to a point that continued harvest was deemed unjustifiable.

Table 1. summarizes the performance of all seven varieties. Bush Early Girl produced the greatest number of early as well as total fruit. As expected, Celebrity produced the fewest number of early fruit.

If fruit number was the only criteria used to judge commercial merit Bush Early Girl would be the run away choice. Consumers, however, prefer large fruit when purchasing slicing tomatoes. If your aim is to grow a sandwich tomato, Bush Early Girl is a poor choice due to its small size. Consider promoting it as a salad tomato.

Sunstart and Sunshine, while slightly less prolific in terms of fruit number, exceeded Bush Early Girl in fruit size. Both varieties combine early ripening with acceptable fruit size, a combination hard to find in most tomato varieties.

If a premium price can be obtained for large fruit consider planting Merced. It is earlier than Celebrity and the half-pound fruit are guaranteed to draw the attention of your customers.

The importance of using early fruiting varieties to optimize the hoop house system cannot be overemphasized. Additional trials will be conducted in the future as new early season varieties are released in hopes of finding the perfect hoop house tomato.