Prices for raspberries in supermarkets are so high. So I prefer to grow my own.
If you have a greenhouse you can even grow them in the winter. This is easy to do. Because the raspberries prefer cool temperatures, the costs of heating the greenhouse is affordable. This is being done commercially now in upstate New York.
Dr. Marvin Pritts, head of the hort department at Cornell University, did pioneering research on this greenhouse crop. The raspberry bushes are left outside until they've received some winter chilling. Then they are brought into the greenhouse. There they are pollinated by bumblebees. The berries ripen during the winter when fruit prices are already sky-high. No pesticides of any kind are needed.
Normally raspberries require a winter chill, so they aren't suitable for tropical climates. A researcher at the University of Florida Tropical Research and Education Center in Homestead, Florida may have come up with an answer.
Bob Knight thinks the solution is for growers in warm areas to buy pre-chilled plants, which can then be planted either in fields or in containers. He found that the dormant, pre-chilled plants began bearing in February.
Since warm Florida conditions won't provide them with their winter chill requirement, they wouldn't yield in subsequent years. So the plants should be discarded after they quit yielding the first year.
Pritts has conducted workshops on greenhouse raspberries at Cornell University. At one such event, researchers from Canada and Belgium were present to discuss their research.
In addition, Pritts tested rowcovers on raspberries. For this research the 'Heritage' variety was used. In his plots the covered plants were taller, and ripened ten days earlier. What was really impressive was the yield. The covered plants yielded four times more berries than uncovered ones.
Pennsylvania State University is conducting research to see how well raspberries do in high tunnels. Generally most crops in high tunnels bear early and have fewer disease problems than those grown in fields.
High tunnels are fairly new to America. In this growing method tall hoop houses covered with greenhouse film are used for growing various crops. Most of the research on high tunnels in the U.S. is being done at the university.
Whether this is practical for home gardeners is unclear. Do-it-yourself types could probably build their own using inexpensive materials, but others would have to buy costly kits.
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