California's Hydroponic Cut Rose Survivors
The number of cut rose growers in North America has dwindled to a precious few, but they cling to their business by diversifying and innovating
The Rose Gene Technology complex outside of Watsonville, Calif., is something of a museum piece, a reminder of days long since gone in the production of greenhouse cut roses in the United States and Canada.
The facility was once used exclusively for research and breeding for commercial rose growers throughout North America. But the number of commercial cut rose growers in North America has plummeted from a peak of around 500 to just 30 or so, as low cost imports from Columbia, Ecuador and the rest of Latin America have captured the market.
Rose Gene Technology survives by diversifying, by combining a cut flower business, a starter plant nursery for cut rose growers and a potted plant breeding facility for garden roses.
"I feel kind of like a blacksmith at the turn of the last century," said George Marciel, sales director at Rose Gene Technology.
Marciel's great grandfather once owned 20 percent of Jackson-Perkins and was the firm's California rose breeder. These days Marciel makes an annual pilgrimage to Holland and brings back 12 to 15 new cut rose varieties that look like they would fit in the North American market. These varieties are then grown on natal briar rootstock in the Rose Gene greenhouses to learn how they will fare under California growing conditions.
"We use our own mix of soil, coconut and perlite. The mixture is around 35 percent soil," he said. The varieties that do well in the coastal California greenhouse environment are then offered to commercial cut rose growers.
There are already about 200 million greenhouse cut rose plants in Columbia and Ecuador combined, according to Marciel, which is enough to fill 90 percent of the U.S. market. But he believes there will continue to be a small North American niche market for the highest quality roses. "There will always be a small market here for people who do things really well."
Variety as the Spice of Business
A few miles away from Rose Gene Technology, California Pajarosa Floral grows 17 acres of hydroponic roses. Alan Mitchell has been able to stay in the greenhouse cut roses business, in part, by investing in the most modern growing technology. In 1993, he converted his California Pajarosa Floral facility outside of Watsonville to hydroponics and began growing his roses in rockwool on rolling benches. Today, there is no rockwool in the California Pajarosa greenhouses. However, the firm has continued to evolve its methods and now grows in a mix of 50 percent coconut and 50 percent perlite.
Coconut has proven to be better for cut-rose production than rockwool and costs about the same. When the firm first converted to coconut a medium of 100 percent coconut was used. But experiments and experience led to the conclusion that the optimum medium is the current mix of coconut and perlite. Production at Pajarosa is also increased by 20% to 30% by bending the weaker limbs downward.
And the firm also improves its productivity by investing in relatively quick turnover of the plants, as the roses are replaced in just 5 to 7 years.
Between 140 and 150 varieties of roses are grown at California Pajarosa. That includes around 50 varieties of spray roses, another 50 or more varieties of hybrid tea roses and the remainder in miniature roses.
Mitchell has a good head start in satisfying water quality regulators because the water from the 17 acres of hydroponic roses at California Pajarosa is already recycled. Irrigation sets are calculated to leach 20 percent of the water out of the bottom in order to prevent excess salts from building up in the medium.
After water leaches from the bottom of the pots, it is captured and sent to a retention pond on the nursery grounds. From the retention pond, the water is sand-filtered and then mixed with fresh well water to irrigate the roses.
A decade ago, California Pajarosa also began working on biological control of spider mites, which are high on the list of cut-rose pests. This approach requires unusually vigilant scouting in order to discover the spider mites when they are still at low enough levels for the predatory mite persimillis to keep them under control.
In order to maintain this biological control for spider mites, the insecticides that are used to control thrips are sprayed at the lowest possible levels, and they are directed high on the plant.
Blue tape is stretched prominently throughout the greenhouses in order to attract and trap western flower thrips. The jury is still out, however, on the effectiveness of this particular control tool.
"My feeling is that when you have millions of thrips coming into the greenhouse, and you have a few thousand go to the blue tape, it mainly makes you feel good," said Tjosvold.
The Bug Eats Fungus
The three major pest problems with cut roses are two-spotted spider mites, western flower thrips and powdery mildew. The predatory mite persimillis can provide effective biological control of spider mites. And this beneficial insect is widely available because many California coastal-area strawberry growers use it in their integrated pest management programs.
But there are no known effective biological controls for western flower thrips. In order to control thrips while maintaining biological control of mites, researchers developed a unique system of spraying insecticides only on the areas of the roses where thrips are likely to congregate.
"By spraying just around the bud we can reduce the water by 75 percent and lower the impact on the biological control in the lower part of the plant," said Michael Parella, University of California at Davis professor of entomology.
University of California researchers have discovered a tribe of ladybug beetles that feed on the fungus that causes powdery mildew on cut roses. Work has begun on the attempt to learn if release of this type of ladybug can be used as an effective part of a mildew control program in commercial flower greenhouses.
