The current issue of Cooking Light, one of the most popular food magazines in the U.S., contains an article touting the peaches of Frog Hollow Farm, an organic orchard in California. The article says that Frog Hollow Farm’s peaches routinely attain Brix levels of 13 to 18 and sometimes higher. It quotes Jon Rowley, a Seattle food consultant who possibly has done as much to popularize Brix as Professor Adolf F. Brix himself, the 19th century German chemist who discovered that the density of plant juices is an indicator of their sweetness.
Jon Rowley has spent the past few years traversing the West Coast with his refractometer, the instrument that measures soluble solids, including sugars, in produce. Refractometer measures are expressed in degrees Brix. The higher the Brix, the sweeter the produce. He was responsible for the “Peach-O-Rama” promotions in a Seattle grocery store chain in which consumers were introduced to the subject of Brix. And he figures prominently in numerous articles in the mainstream press, from Vogue to Sky (Delta’s in-flight magazine) about good flavor and its correlation to Brix.
“I’ve had great success basing retail promotions on high-Brix fruits and vegetables,” he says. “If a farmer has the goods, Brix can be a powerful marketing tool. Brix isn’t all there is to flavor, but you can’t have great flavor without high Brix.”

Raising Brix
Sounds good, but how does a grower get high Brix? Great flavor is something all market gardeners strive for – it’s part of what makes locally grown produce so much more desirable than produce picked early and shipped thousands of miles. And usually good flavor just happens because market gardeners grow the most flavorful varieties, pick them when they are ripe, and sell them quickly.
Still, most growers have had the experience of growing a crop that looks great but just doesn’t have much flavor. Maybe it was strawberries that got big and red, but stayed tart. Or melons that never developed that irresistible aroma. Or carrots that tasted almost metallic, rather than sweet.
The reasons for poor flavor are usually not clear. It could be the variety, the weather, soil nutrients or some mysterious interaction of factors. The fact of the matter is that flavor is hard to predict or control. For most growers, finding the best-tasting varieties is a matter of trial and error and more trial and error.
Some growers, though, believe that they can greatly enhance crop flavor by production practices and monitoring with the refractometer and other instruments. The spectrum of practices ranges from general attention to plant nutrition through soil testing and amendments, to the more explicit recipes of the Reams biological farming system, which was developed by the late Carey Reams and now advocated by several prominent farm consultants with ties to the magazine Acres USA.
Unfortunately, there is no simple prescription for raising Brix levels. And explaining the huge range of philosophies, theories and practices that apply to Brix is beyond the scope of this article. But for growers who are perhaps wishing for better flavor in their produce, here are some highlights to get you started and resources for further research.

What the research shows
The typical research approach of replicated trials, published in peer-reviewed journals, is lacking on this topic, cautions Steve Diver, a technical specialist at ATTRA, the information resource for alternative farmers. But there’s plenty of grower experience providing guidance to those who want to learn more about how to have great Brix.
Jon Rowley, though not a farmer, is dedicated to figuring out the connection between agricultural practices and flavor. He conducts his research at the Interbay P-Patch, a community garden in Seattle with 130 gardeners. The garden is devoting eight 10×10-foot beds to a 10-year soil-building research project to better understand the role of organic matter in soil. They have the soil tested each year for minerals and the web of life it contains, and request fertilization recommendations for the crop grown in each bed, but follow those recommendations only on beds that receive no organic matter.
“I have thousands of Brix measurements which I have tried to correlate with farm practices,” he said. “I measured Brix in fruits and vegetables compulsively for about six years before the light bulb went on. Organic matter in soil is a key factor. We took a community approach to composting, mulching and in general getting organic matter decomposing into soil. The Brix levels of just about every vegetable rose each year for the three years we tracked it.
“Plant spacing and watering are also aspects of getting Brix up. When organic matter levels are high, especially if you have a mulch on the ground, soil holds moisture better and plants can more easily take what they need when they need it. I think this results in optimum conditions for photosynthesis which results in higher sugar output and higher Brix.”

Another key component often associated with high Brix levels is foliar feeding, in which plants are misted with dilute nutrient solutions. Plant response to foliar sprays is much faster than through equivalent soil applications, with research showing four to 15 times more uptake of foliars, says Amigo Cantisano of Organic Ag Advisors. “Foliars use relatively small amounts of fertilizers to effect nutritional changes, with immediate and significant plant response,” he says.
Spraying should be done in the morning or evening, and a surfactant should be added to the solution to decrease surface tension on the leaf to increase absorption. Both sides of the leaves should be coated.
Foliar feeding can provide quick supplemental doses of minor and major plant nutrients and, in the case of seaweed, growth-promoting hormones, says Steve Diver of ATTRA. Biostimulants, biocatalysts, homeopathic preparations and hydrogen peroxide are sometimes included in foliar programs to affect plant growth or ward off insect and disease attack through non-nutritive means, he said. Before spending a lot of money on a formula for acres of produce, growers are advised to check Brix before and after spraying a small area. If the Brix increases one or two degrees, the plants are responding to that mixture.
Ed Welch of Sunny Pine Farm in Twisp, Washington, uses foliar sprays on his vegetable crops regularly and when they are stressed. “I have been successful in keeping Brix levels up with severe weather conditions and heavy smoke from more than two weeks of forest fires in our area using foliar nutrient sprays,” he says.
Ed checks Brix with a refractometer every week and before and after foliar applications. “If the foliar application was any good it should increase Brix at least one point shortly after application,” he says. “I mostly check the potatoes because I grow more of them and I have more trouble keeping them healthy and insect free. I have learned that with potatoes the colorado potato beetle begins to be less of a problem at 13 Brix from leaf sap. At 15 Brix and above the potato beetle stops eating the leaves altogether.”
Many growers believe that plants with Brix above 12 become resistant to pests. They also contend that high-Brix plants withstand lower temperatures and can survive frosts.
Crop consultants offer numerous formulas for foliar feeding, based on the needs of individual plants. Tissue testing is required to address specific problems, but a more generalized foliar feeding program is often used by growers as a preventative. A mixture of fish and seaweed is one of the most common foliar feeds used as a general supplement. Compost tea is also gaining popularity. Other materials sometimes used, depending on crop need, include rock phosphate, wood ashes, gypsum, milk, molasses, sugar, epsom salts, chelated iron and others. Farm suppliers such as Harmony Farm Supply offer a wide range of fertilizers appropriate for foliar feeding. Biodynamic farmers have specific preparations appropriate for foliar feeding. Reams Biological Farming practitioners also have highly specialized foliar sprays based on whether the crop is in a vegetative or fruiting stage.
Another approach to improving produce flavor is remineralization, which involves the application of rock dusts, finely ground rock minerals, to the soil, to compost teas, foliar fertilizers, and to compost piles.
“A common notion among organic farmers is that rock dusts provide key mineral supplementation that enhances the ‘strength’ and ‘vitality’ of plants and thereby increases resistance to insect attack as well as improves the flavor and nutrition of crops,” writes Steve Diver of ATTRA. “Concepts and terms like ‘strength’ and ‘vitality’ come from the practitioner experience rather than scientific literature, nevertheless they mean something to farmers who work closely with the soil. To support their claims that rock dusts enhance the sugar and mineral content of fruits and vegetables, the refractometer is commonly used to evaluate soluble solids. As Steve points out, there is little or no “traditional” science on this topic. But university researchers were slow to catch up with organic farming research in general.
“It doesn’t look like crop quality, or what you and I consider quality, has been a focus of university research over recent decades,” Jon Rowley comments.
That may be changing, though, as researchers start to pay more attention to the flavor of food and the marketing edge good flavor can provide. University of Georgia researchers tested Brix in locally grown carrots compared to California carrots in search of a variety that could create a better market for southern carrot growers. And several research projects under way with support from the Organic Farming Research Foundation address the topic of flavor, nutrition and their relationship to farming practices. This is clearly an evolving field of inquiry. Stay tuned.

For more information
•The best introduction to Brix, the benefits of high-Brix foods, and the use of the refractometer is Rex Harrill’s “Brix Book” on the web at http://www.crossroads.ws/brixbook/BBook.htm
•ATTRA has several publications on the topics mentioned above, including Foliar Fertilization and Rock Dusts in Agriculture. There are available on the web at www.attra.ncat.org or in print (free) by calling 800-346-9140.
•The 2000 volume of Growing for Market has two columns by Amigo Cantisano with detailed advice about foliar feeding: what to use for various purposes, and in what amounts; plus tips for spraying to achieve best results. The 2000 collection is $20 postpaid. See page 2 for ordering information.
•Acres USA has many books and pamphlets about Reams biological farming. For a catalog, call 800-355-5313 or visit www.acresusa.com.