Urban Farming in Hawaii
The Sumida family has been leasing the land from Bishop Estate for more than 72 years. The Honolulu City Council has passed a wetland act to preserve the farm, because two endangered species of birds live there.
There are other factors that make the farm unique. For example, the cap rock springs that lie underneath the area (spring water oozes from tiny cracks in the cap rock) provide the food source essential to successfully growing watercress. The pH is 7.0, which is ideal. The water is part of the drinking water supply for Oahu, and the cap rock springs lie 100 feet below the surface.
With increasing development of the area, the springs have been covered by concrete, causing them to die. As a result, the overall supply of spring water in the area has been reduced.
Despite these factors, however, the farm has managed to thrive in an ideal environment that is relatively free of pollution – including carbon monoxide from the nearby six-lane highway.
In fact, according to operations manager David Sumida, disadvantages related to the farm’s location are non-existent.
“We’re the only watercress farm in this area with spring water, as compared to artesian water,” says Sumida. “For example, the water may look brackish on some farms, so every farm grows a different variety of watercress to be compatible with the type of water they have. We grow the Florida variety, and it grows best here.”
Another unique aspect about the farm is that the average age of its workers is 65. Sumida has to figure out a way to retire the workers. He makes sure workers are happy and comfortable.
Growing and Harvesting the Crop
Watercress is a member of the mustard family. The vegetable has small, crisp, dark green leaves and has a pungent flavor. It can be used in salads, sandwiches, soups and a variety of cooked dishes. In Hawaii, watercress is grown all year. Winter is best for the crop, and summer is the least desirable.
Watercress is a temperate crop, so it likes winter and cold temperatures. The crop does poorly during summer, because the water warms up and it is not ideal for watercress. The growth of watercress is restricted in hot weather.
Nutrients are not pumped to the crop. They are naturally found in the water. Sumida declines to talk about nutrients used on the crop as needed but notes that watercress is sensitive and fragile, so the vegetable responds to different stimuli.
For example, watercress is sensitive to subtle changes in weather. On a particular day, the watercress may appear healthy, while on another day, the crop will appear sickly. Factors such as water and air temperature exert dramatic fluctuations on the appearance of watercress.
“Ideal conditions for growing watercress are winter days, with lots of sunlight and no clouds,” says Sumida. “The watercress will grow more than one inch in one day. It takes eight weeks for the watercress to reach maturity. We take additional steps to prolong the shelf life of the watercress, and to reduce labor. For example, regarding prolonged shelf life, this allows us more time to deliver the watercress to our customers. Some of the other farms are more labor-intensive, and they have to deliver their crop to their customers immediately.”
The farm exports watercress to the outer islands and produces about six tons of the crop per week. “Our watercress is a hardy variety, and we plant the crop with cuttings, not with seeds,” says Sumida. “We use a pattern with harvesting by staying in one area each day. We work upstream to downstream, and we zigzag. The good water will come down as we harvest, and go to the next patches. We get about five million gallons of spring water daily. It takes about one million gallons to grow one acre of watercress. We have about nine acres, so we are actually about four million gallons short.”
The supply of spring water was more abundant 20 years ago. To compensate for the shortage, the farmers monitor water control, ensuring that the spring water is directed to areas where it is most needed.
For example, after the crop is harvested, the water supply is shut off – because the new cuttings do not require much water. Approximately three weeks later, the water supply resumes.
Harvesting is by hand, and as the crop is harvested, roots are left in the patches. Watercress is left along the edges of the patches, and is ideal for cutting to replant the crop in the patches. After harvesting is completed for the day, the farmers return to the patches to replant cuttings, row by row, on top of the roots.
“By cutting the watercress, we make this water channel around the rim of the patch, which is important because it will let the water go around the young watercress into the next patch, where it is needed,” says Sumida. These roots are good for one to two years. After that, they get tired, We can tell if that is happening when a patch is not producing as much as it should. At that point, we remove all the roots and dispose of them in a landfill. We then replant the patch. It is by feel, with regard to how much watercress is bunched, and each bunch is equal, which comes to about 14 ounces to one pound.”
The Post-Harvesting Process
After the watercress is harvested, the crop is washed and bundled into bunches of 30 each. The crop is then placed upon skiffs which hold 36 bundles, or a half-ton of watercress. From that point, the watercress is loaded into a Vacuum Cooling Chamber, which rapidly cools the crop – prolonging the freshness of the watercress.
This key step in the process increases the shelf life of the crop up to one week or more. Watercress that has not been chilled lasts approximately three days. The chamber was the first device of its kind built in Hawaii in 1960, and there are seven devices in Hawaii.
The specially designed chamber chills a half- ton of watercress to 37 degrees in 40 minutes. In comparison, if the watercress is placed in the farm’s reefer, it takes 24 hours to chill. Watercress dies in 24 hours, because it becomes warm first, before becoming cold. The chamber eliminates the warming process.
While in a vacuum, the water on the crop boils and evaporates, extracting heat from the watercress. Refrigeration units on the inside of the chamber convert water vapor back into water. The crop goes into the reefer when the cooling process is completed.
“Watercress harvested yesterday, would still be fresh today,” says Sumida. “We can store vacuum cooled watercress for up to three days. We’re a combination of low-tech and high-tech. The water control is low-tech, because we basically move a rock from one place to another to control the flow of water. Our sprinkler system, which combats infestation of our crop, is the high-tech end.”
The Joy of Farming
“The most satisfying part of my job is being here,” says Sumida. “I love working with watercress and take a lot of pride in growing the crop. I enjoy conducting field trips when students from the schools visit us. All kinds of people visit us and I enjoy telling them about our farm. As watercress farmers we have an agreement that we have our own customers, and that we will not steal other farmers’ customers. We help each other and we share ideas.”
In annual gross sales, Sumida generally sets a goal of $500,000. But even if the farm reaches that goal, with the cost of operating the farm, Sumida makes little profit. Sumida Farm is one of approximately seven watercress farms on Oahu, and is the largest watercress farm in Hawaii, supplying 50 percent of all watercress in the state.
The demand for watercress in Hawaii has always been greater than the supply. Sumida’s grandfather, Moriichi, started the farm in 1928. His father, Masaru, took over the farm in 1950. Sumida and his sister have been operating the farm since 1982.
