Lancaster, Pa.—On a beautiful sunny morning in late June, it is hard to believe that southeastern Pennsylvania is not the perfect climate for growing grapes. In some ways it is, but everyone knows that growing high-quality winegrapes east of the Rockies is a proposition that faces multiple challenges. Winters are too cold; summers are hot and humid; there are late-season frosts in the spring and early frosts in the fall, and it is a rare harvest when it doesn’t rain. It would be impossible to mitigate all of those vagaries of the weather, but a new technology can help to lessen the impact of some undesirable weather events and significantly improve the quality of high-value winegrapes.

On Wednesday June 27, Ralph Cramer and his son Keith hosted an open house at their farm outside Mount Joy, Pa., for anyone interested in learning more about the advantages of Haygrove Tunnels, otherwise known as “hoop houses.” The Cramers are second- and third-generation farmers who grow fresh and dried flowers in Lancaster County, Pa., and now also sell the three-season tunnels. Like the strawberry farmers who first developed the tunnels in England, the Cramers first became interested in the tunnel project to improve their crop quality and extend the growing season so that their agricultural commodity could be on the market first during the early season and last toward the end, when the prices are at the highest. The Cramers initially planted grapevines under a high tunnel in 2010. The vines have completely filled the trellis, and the family expects to have a full crop of Cabernet Sauvignon and Petit Verdot this harvest.

The reasons for using tunnels for winegrapes are somewhat different from other crops. Tunnels allow growers to control and manipulate the environment for growing grapes to improve the quality of high-end varieties on a consistent basis by offering protection from late spring and early fall frosts and by allowing the grower to regulate the amount of water that the vines receive. In California and other dry climates, grapevines switch from a vegetative growth cycle to a fruit-ripening cycle based on the lack of moisture available to the plants. East of the Rockies the rainfall levels may or may not stop at the appropriate time.

Mark Chien, state viticulturist at Penn State Cooperative Extension and Wines & Vines contributor, spoke about the problems of growing grapes and the potential advantages that using tunnels can offer. “We lose more fruit and wine production to frost than to diseases and insects,” Chien noted. “Whether you believe in climate change or not, in the East we seem to be having both an earlier and warmer start to the growing season, and therefore earlier bud break. For us, this means we have three more weeks of frost season, and tunnels can offer some frost protection.”

One type of tunnel, known as a “high tunnel” has been designed for crops such as grapes that require a trellis system to be in place. A high tunnel is basically a three-season greenhouse constructed of metal hoops and plastic. Metal posts are driven into the ground about two feet deep; then metal hoops are attached to the posts to create the arched support structure for the greenhouse grade plastic that creates the roof and sides of the tunnel. While clear plastic is available, most of the tunnels are covered with a luminance plastic that diffuses the sunlight and reflects infrared light. The plastic is held in place by an arrangement of crisscrossed ropes. Each tunnel is 18-30 feet wide and 10-18 feet high—wide enough to cover four rows of grapevines and high enough to allow tractors and other vineyard equipment to drive down the rows.

The plastic covering can be rolled up on the sides and ends of the tunnel to allow for air flow during the growing season or put down to protect the vines from rainfall or to modify the temperature so that the vines are not affected by frost either in the spring or the fall. The ability to extend the growing season by two to three weeks for a high-end wine variety can significantly increase the ability of the grapes to ripen fully, and that can make the difference between a good wine that will sell for $15 per bottle and an excellent one that will sell for twice as much.

Because of the cost of adding a tunnel to the already high cost of planting a vineyard (now estimated before land costs to be at least $30,000 per acre in the East when drain tile, deer fence, trellis, vines and irrigation are included, not every grower may be interested in erecting tunnels over part or all of his or her vineyard. Winemakers who want to make good quality, everyday wines that people enjoy drinking can plant grape cultivars that will give them good fruit on a regular basis without tunnels. However, for growers and winemakers who want to make high-end, high-value wines that will compete successfully every year on the world stage, high tunnels are tools to help achieve that goal. The ability to reduce the excess rainfall that often arrives post-veraison and during harvest can be a critical factor in increasing wine quality.

Chien noted that there are a number of questions about tunnels for future research to address. One such project is being conducted by Richard Carey at Vitis Research and Tamanend Winery in Lancaster, Pa., where half the vines are under a high tunnel and the other half are not covered. The vines were planted in 2010, and in the second season the difference in their growth was dramatic. Those under cover were more vigorous, more fully established and ready to bear a crop in their third season.

Additional questions to be answered include:
1) The effect of diffusion of light on insects such as Japanese beetles: There is anecdotal evidence that Japanese beetles don’t like light diffusion and therefore don’t cause as much damage in a tunnel as on uncovered vines, especially young plants;
2) The possible reduction in disease potential because of lower humidity under the tunnel. Again, there is some evidence that fewer sprays are needed because of the control of rainfall on the vines in the tunnel.
3) The ability of vines to acclimate sooner for cold temperatures when the grap es are harvested earlier and therefore get through cold winters with less or no winter injury.
   
Keith Cramer recommends two types of high tunnels for vineyards in the East. The first is a “starter” kit for getting a grower into a tunnel program. The kit consists of a “Super Silo” high tunnel measuring 25 feet x 200 feet, or 5,000 square feet, with 5-foot sidewalls and covered by luminance plastic. The cost for the kit is $8,995.

The second tunnel, the minimum size that the Cramers carry, is a 4-Series multi-bay tunnel that covers half an acre. This tunnel system has three bays, each measuring 24 feet x 300 feet. It costs $21,000.00 (96 cents per square foot), not including the labor to set it up. He noted that the kind of tunnel used east of the Rockies is more robust than in California because of the difference in wind speed. Wind in California rarely exceeds 35 mph, while in the East wind speeds up to 60 mph are not uncommon.

For more information, contact Haygrove Inc. by phone at 717-492-4955 or visit haygrove.com. On the West Coast, contact dominic.criscenti@haygrove.com.