High tunnels

Ball Tagawa Growers (BTG) in Arroyo Grande, Calif., uses high tunnels, especially when space is at a premium.

“We fill our greenhouses with spring plug production (January through April) so we needed additional growing area for the Ball Ornamentals production,” said Steve Sapone, site manager at Ball Tagawa. “The tunnels provide a cost-effective easy to construct a solution.”

BTG uses high tunnels for a variety of crops, including abelia, buddleia, euonymus, jasmine, gardenia and perovskia.

“We have stock plants growing in 6,900 square feet of Haygrove tunnels, and our liner production in 32-count trays is being grown in 16,000 square feet of AgraTech tunnels. We will be adding another 15,000 square feet before the end of the year for liner production,” he said.

The AgraTech tunnels are used for liner production where the “plants grow and hold very well prior to shipping,” Sapone said.

The Haygrove tunnels hold some of BTG’s stock production.

“The idea is to provide the stock plants with protection and an environment that will cause them to produce cuttings year round. We have let some of the stock plants mature and they look great. They would probably work fine to finish plants in, depending on the location of the nursery,” he said.

Tunnel construction
Some growers would argue a high tunnel and a cold frame are one in the same. But BTG’s tunnels are gutter-connected to make a range, where cold frames are usually single structures, Sapone said. The end wall doors roll up to allow good air flow and some are designed to vent the roof ploy by sliding it up on the bows.

“Cold fames are more closed up with smaller openings and often only a small door,” he said.

Tunnels are also designed to be portable. The sidewall posts are not set into the ground with concrete.

“Our Haygrove tunnel roofs are held in place by ropes rather than locks so the poly can be quickly removed and reused. Cold frames are designed to overwinter plants and are built for different levels of snow load in mind. Tunnels would not work in that situation,” he said.

BTG’s tunnels are located at the back of the nursery next to a boiler system that heats the quonset houses.

“We have piped hot water over to one of the tunnel ranges from the boilers and have installed micro-tube bottom heat. This helps keep our stock vegetative and our liners growing during the cooler season,” he said. 


For more: Ball Tagawa Growers, (805) 481-7526; AgraTech, www.agra-tech.com; Haygrove Ltd., www.haygrove.co.uk.