Growing strawberries in a greenhouse eliminates dependence on methyl bromide, avoids excessive water use for plant establishment and frost protection, and minimizes pesticide use, according to Daniel Cantliffe and Ashwin Paranjpe of the University of Florida’s Protected Agriculture Project. Writing in American Vegetable Grower, the researchers report that greenhouse strawberries also fetch a higher price because they can be produced in the off season.
Greenhouse strawberries are typically grown in PVC troughs filled with a soilless substrate such as pine bark, and irrigated with drip tape. Because berries hang down, the trough can be adjusted to keep the fruit at eye level, making harvest quicker and less painful to the harvester’s back. The troughs can be spaced 20 to 30 inches apart with more than three plants per linear foot, or densities as high as 98,000 per acre. Early yield in the greenhouse can be two to three times greater and the total yield three to four times greater than that of field-grown strawberries in Florida.
Biological controls work well on greenhouse strawberries: Aphidius colemani wasps and pink-spotted lady beeetles eat aphids’ predatory mites such as Neoseuilus californicus control two-spotted spider mites and Orius insidiosus (see next article) controls thrips.
Fungal pathogens sucha as Botrytis is negligible in the greenhouse. Powdery mildew is common, but can be controlled with biofungicides.
Strawberries need minimal heating – just enough to keep the temperature above freezing – and passive ventilation.
For more information, visit the website www.hos.ufl.edu/protectedag.