Gordon Johnson, Extension Vegetable & Fruit Specialist; email@example.com
Over the last 2 years – hot and dry in 2012 and cool and wet in 2013 – tomatoes grown in high tunnels have outperformed field tomatoes. The high tunnel environment provides more heat early in the season and therefore earlier harvests. In the summer, the high tunnel provides a rain shield and protection from storms, reducing disease pressure dramatically and eliminating fruit cracking. Later in the year, the tunnel again provides extra heat, extending fall production. While there is some loss of fruit set in the heat of the summer, reducing August production, fruit quality is still superior.
One researcher likened the high tunnel to a “desert environment”. I like to think of it as creating a “Mediterranean climate” which is very conducive to growth of many vegetables. In addition to the reduction in disease pressure, insects are also less of a problem as many do not prefer the tunnel environment (spider mites are an exception to this and mite pressure often increases).
Single early spring tomato plantings will produce well into August, decline, and then pick up again in September with determinate slicer types. Indeterminate types (most cherry tomatoes, some slicers) may get so big that they are hard to manage late in the year. Replanting after early production peaks (late July) can be another tool to get higher fall production and manage plant size.
For direct marketers, the high tunnel is becoming an essential tool for tomato production. We are fortunate to have several universities in the region that conduct tomato trials in high tunnels. In particular, Penn State has good trial data and resources for high tunnel tomato growers.