High Tunnel Extends Growing Season with Tulips

April 7th, 2009

AMES, Iowa — Iowa State University researchers showed high tunnels can be used to extend the growing season by cultivating tulips over the winter at the Armstrong Research and Demonstration Farm in southwest Iowa.

High tunnels are similar to greenhouses, but less costly to construct and operate. They are usually unheated, side-ventilated, plastic-covered structures. The crop is grown directly in the soil covered by the high tunnel.

"Although some growers around the Midwest are producing crops year-round in their high tunnels by growing greens and other cool season crops, most are not utilizing them between December and April," said Linda Naeve, ISU Extension program specialist in value-added agriculture.

There is a lot of interest from growers in high-value specialty crops that can be grown in high tunnels and increase their profitability, she said. Tulips, daffodils and other spring cut flowers may fill the production gap in a high tunnel and provide Iowans with a sneak preview of spring.

Bernie Havlovic, Armstrong Farm superintendent, said the tulip project represents the third crop in the high tunnel for the year. He added that the tunnel is needed by April 15 for planting vegetables.

Last November, 100 bulbs each of 13 tulip cultivars were planted to see how they would perform and if their quality as cut flowers would be acceptable to local floral shops. Workers at the Armstrong Farm began harvesting the tulips on March 23 with delivery to local flower shops.

The tulips planted for this project filled about a quarter of the tunnel's capacity. The plants were covered with row covers to delay emergence, and later to protect them from cold evening temperatures.

"Overall, the project was a success," said Naeve. "The florists were a bit skeptical at first, but once they saw the tulips' superior size and quality, they were excited to get them."

The research was supported by a grant from the Leopold Center for Sustainable Agriculture.


Linda Naeve, ISU Extension, (515) 294-8946, lnaeve@iastate.edu

Bernie Havlovic, Armstrong Research and Demonstration Farm, (712) 769-2402, bhavlovi@extension.iastate.edu

Ed Adcock, Agriculture and Life Sciences Communication Service, (515) 294-2314, edadcock@iastate.edu