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High tunnel system produces fall berries

A new system of strawberry production has resulted in quality berries this fall at the Penn State High Tunnel Research and Education Center.
A new system of strawberry production has resulted in quality berries this fall at the Penn State High Tunnel Research and Education Center. Photo provided

Gardeners and commercial growers who want to produce beautiful strawberries in the fall to go along with their fall harvest can try a system of production under development at Penn State.

The system is being developed by two of my colleagues in the department of plant science, Small Fruit Extension Specialist Kathy Demchak and Research Technician Matt Cooper. The research is being conducted at the Penn State High Tunnel Research and Education Center located at the Horticulture Research Farm on state Route 45, past Pine Grove Mills.

The system can be for outdoors or in a protected structure like a high tunnel or a greenhouse. It revolves around the strawberry variety Albion, a day neutral variety that is everbearing. The variety can be purchased online from Nourse Farms in Massachusetts, where a wealth of information on small fruit crops can also be found. Albion can be planted in the garden on black plastic mulch or in a protected structure such as a high tunnel or greenhouse. The research high tunnels at the Penn State facility are 17 feet wide and 36 feet long and covered with a single layer of plastic. This research project is one component of a large federal multistate grant from the United States Department of Agriculture that involves evaluating a number of different plastic coverings on the high tunnels and as low tunnels in the field.

In the high tunnels the strawberries are planted in mid-May in 1-gallon grow bags that are white on black where the outside color is white. These are filled with an artificial mix composed of  2/3 peat moss and  1/3 perlite. The pot is 8-12 inches deep, permitting easier management of moisture, which is critical to the production of quality berries. The bags have holes in the bottom to permit excess moisture to drain out. The bags are spaced 1 foot apart in staggered double rows to ensure good airflow around the plants.

Once planted, it is advised to keep removing the runners that develop. Kathy also recommends removing the first flush of blossoms that develop so as not to reduce the vigor of the plant. Watering needs to be even to ensure large size and nicely shaped strawberries. With each watering, soluble fertilizer is applied through the drip irrigation system. Home gardeners can use  1/2 tablespoon of Miracle Gro or a Peters 10-20-10 or 20-20-20 mixed in a 5-gallon bucket for each watering.

Kathy said that pollination of the strawberries was excellent, resulting in nice large berries. Harvest of the strawberries began the beginning of July and continues every other day. Leave the berries on until they are fully red for the best flavor. Hot night temperatures will decrease the sugars. As the temperature drops the berries will become firmer and sweeter. On average it takes 15-20 berries to fill up a quart basket.

As the temperatures become cooler later in the fall, row covers can be used over the plants at night and removed during the day to prolong harvest until the temperature under the row cover reaches 30 degrees Fahrenheit and the plants shut down.

If you’re doing this in your garden, Kathy recommends using black plastic mulch, with drip irrigation and planting the strawberry plants in a double row 18 inches apart and with the plants 12 inches apart in the row.

I believe this a great system of production for both the home gardener and also the commercial grower. Thanks to Kathy and Matt for developing this system and sharing this information.

Bill Lamont is a professor and extension vegetable specialist in the department of plant science at Penn State and can be reached by email at wlamont@psu.edu.