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Thin Your Grove to Increase Yieldby Daphne Lewis, August 1998

I have been harvesting and selling bamboo shoots from two small groves of Phyllostachys nigra v.Henon located in Kirkland, Washington, for three years. I have two purposes. The first is to demonstrate that there is a market for fresh, locally grown bamboo shoots in Washington State.The second is to generate data on yield. Our two groves together measure just under 2000 square feet.We have sold their output to a large produce broker/warehouse since 1996. Because the quantities are small, our sales demonstrate our broker's willingness to try something new and her dedication to organic produce more than that there is a significant market for fresh bamboo shoots. Nevertheless I believe and she believes that there is a significant market. The produce buyer paid us $2.00 a pound in 1996 and '97 and $2.50 a pound in 1998.

The two groves are on the same property. The more productive grove is the Driveway Grove. It is over 30 years old. It measures approximately 750 square feet and is shaped like a banana. It grows on a steep slope between the driveway to the south and a tiny stream to the north. The bamboo does not spread into the compacted soil of the gravel driveway and does not cross the stream. It does spread into shrubbery at the narrow west end of the banana shape and into the lawn at the east end.

The North Grove is over 15 years old. It is a hedge on the north side of the lawn measuring approximately 1200 square feet. Behind it rises a very steep slope to the neighbor's house. The bamboo has never climbed this slope. It prefers to run south into the sun and moisture of the lawn and garden beds. The North Grove is a lower quality grove than the Driveway Grove. It has patches where there are no culms and patches of small crowded and/or dead culms. Where crowded most of the culms are under an inch in diameter. An assortment of dead and dying bushes and trees clutters the grove. We are in the process of thinning small and crowded culms and clearing bushes, trees and weeds.

The Kirkland henon groves are a perfect example of how well henon bamboo will grow on its own in Seattle's Mediterranean, maritime climate. While the groves have been greatly admired over the years, they have received minimal care. Care of bamboo in our climate falls into the categories of watering, fertilizing, and thinning. And also restraint from random digging and removing.

First—water. Seattle receives 36 inches of rain a year. Rain falls in fall, winter, and spring, but mostly in December and January. Our dry season is June, July, August, and September. During those four months we are a desert receiving 3 to 6 inches of rain. Bamboo grows better with 3 to 6 inches of rain a week. Our groves have not been irrigated in summer.

Second—fertilizer. Until the summer of 1997, our groves had not been fertilized. That summer a 50 pound bag of Webfoot 7-7-7 and a 20 pound bag of Ironite were scattered on both groves. Cow manure was spread on the Driveway Grove. The North Grove did not receive manure.

Third—thinning. Until the summer of 1995, our groves had not been thinned. The canes were crowded. Many were half dead. In 1995 we thinned a third to half the poles from the Driveway Grove and a few from the North Grove.In 1996 we thinned the Driveway Grove again and began on the North Grove. It still needs a lot more thinning. Both groves have been weeded of field bindweed, English ivy and other less tenacious weeds.

Fourth—digging. For many years the owner generously had allowed people to dig clumps of bamboo and take them home. This digging explains why the North Grove has numerous empty spaces in it. Without summer rain it takes time for rhizomes to fill in where they have been removed.

Please refer to the graphs titled "dates of harvest".

Duration of Harvest
Spring of 1996 was unusually cold and rainy. Our first harvest was May 28, two weeks later than usual; our last was June 23. Harvest lasted 26 days, less than four weeks. The harvest in 1997 was 24 days, also less than four weeks. The harvest in 1998 lasted the longest: 33 days. It began 5 days before and ended 4 days after the harvest in 1997. Our results show that unirrigated henon in the Puget Trough will produce sellable bamboo shoots for a month each spring. The length of harvest is more than three and less than five weeks.

Distribution of Yield Within the Shooting Period
The distribution of yield patterns shown by the three graphs vary each year. In 1996 overall yields were very low. The yield pattern is pretty flat. The final two bars are peaks but looking closely, it is clear that the final harvest was 9 days after the preceding one. If harvesting had been done twice a week there would be no peak and the flat pattern of the previous two weeks would continue. The 1997 pattern has a peak in the middle. At the start and at the finish, yields are low. The middle of the harvest period was far more productive than the start and finish. In 1997 we concluded that a poor grove produces slowly throughout shooting period. A better grove produces strongly in the middle of harvest season.The end of the harvest period has arrived, when the yield declines precipitously. The pattern in 1998 was different again. The very first and last harvests were low but the middle ones were more plateaulike than bell curved. The one just before the last was the second largest! So for now we think that a well managed grove will produce well for most of its four week harvest period, but not the very first cutting or the very last.

Pounds per Acre
Please refer to graphs "Pounds of Bamboo Shoots Harvested"

Information on yield per acre comes from China and other Southeast Asian countries. Figures vary greatly. Chinese yields vary from 5 tons to more than 10 tons of fresh shoots per acre per year. In addition the weight of poles varies from 5 to 10 tons per year. If groves are managed for poles, more tonnage of poles are harvested and less of shoots. If poles are managed for shoots, more tonnage of shoots are harvested and less of poles. What would be a farmer's yield in Puget Sound country? My instinct tells me it will be less than the Chinese best figures. Our worst per acre yield was in 1996 in the North Grove. The grove yielded 50 pounds total, the equivalent of 1800 pounds per acre. Our best per acre yield was in 1998 in the Driveway Grove. The grove yielded 97 pounds, the equivalent of 5600 pounds per acre. See chart. Note that our best figure is half of the lowest figure given for China.

Each grove has increased productivity each year due to thinning. It is not due to increased irrigation or fertilization. For right now the Driveway Grove is properly thinned for the diameter of its culms. We expect that next year it will send up culms larger than the existing ones. If this occurs, we will need to thin more culms in order to increase the average distance between the culms. The space needed between culms depends on the length of the branches which of course are longer on bigger culms. The North Grove needs a great deal more thinning than we have done so far. We will perform this work in September. We expect a significant increase in productivity in 1999 in the North Grove, assuming we do the required thinning.

Is there a market for fresh bamboo shoots?
I asked our broker. In Seattle the Asian groceries and restaurants tend to buy from Asian Specialty Distributors and to have their own supply system.Our broker is not in that loop. She is in the mainstream loop. She sold to a couple of stores and a few restaurants. She made somewhat contradictory observations. On the one hand she said there is a good market. Each year she sold more of our bamboo shoots than the previous year. Last year she had some unsold shoots; this year she did not. On the other hand she also pointed out some problems with selling fresh bamboo shoots.

An obvious problem is that American consumer does have much knowledge about bamboo shoots. The broker suggested developing point of purchase information, perhaps stem tags or twist ties with instructions. Moreover, bamboo is difficult to prepare. It must be peeled. It must be parboiled. You don't have to do that with asparagus or mushrooms. Our price of $2 to $2.50 is too high to sell in quantity. If she buys the shoot for $2.50 a pound, the store sells it for $5 a pound.

We will continue to document shoot yields of our Kirkland Groves. The North Grove should increase productivity dramatically in 1999 because we will finally complete its thinning in September, 1998. We are working with Steve Fransen of Washington State University Puyallop to arrive at figures for the nutritional value of bamboo leaves and culms both as as forage and as sileage. In May together with Steve we cut and weighed poles and sent same through the ensilage machine at Carnation Research Farm not far from Kirkland. The results of that research are scheduled to be available by the end of October.