Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Potting Mixes for Certified Organic Production


Published on

Potting Mixes for Certified Organic Production

Published in: Education, Technology, Business
  • Be the first to comment

  • Be the first to like this

Potting Mixes for Certified Organic Production

  1. 1. Potting Mixes for Certified Organic Production HORTICULTURE TECHNICAL NOTENational Sustainable Agriculture Information Service Abstract: Organic production of seedlings, transplants, and potted plants requires the use of media that meet the requirements of the National Organic Standard. This publication lists commercial sources and provides formulas and guidance for on-farm preparation of approved media.By George KuepperNCAT Agriculture Specialistand Kevin Everett, Program InternSeptember 2004©NCAT 2004 INTRODUCTION Farms and nurseries use various seed- ling and potting media in the production of field transplants, container plants, and greenhouse crops. Such media may contain a wide range of natural and synthetic materials. In certified organic production, there are limitations on the materials that may be used, either as base substrates or for supplemental fertilization. This publication will help organic producers find commercial sources of organic potting media— or make their own. Table of Contents INTRODUCTION .................................................................................................... 1 COMMERCIAL BLENDS ............................................................................................ 2 MAKING YOUR OWN ............................................................................................. 2 INGREDIENTS ALLOWED IN ORGANIC POTTING MEDIA ..................................................... 3 COMPOST AND MANURE RULES ................................................................................ 4 APPENDIX 1: SOURCES OF ORGANIC POTTING MEDIA, UNTREATED PEAT MOSS, COIR, AND OTHER APPROVED INGREDIENTS ................................................................................... 11 APPENDIX 2: RECOMMENDED GUIDES FOR LEARNING TO MAKE POTTING MEDIA.................. 14 APPENDIX 3: RECIPES FOR GROWING MEDIA .............................................................. 15 ATTRA is the national sustainable agriculture information service operated by the National Center for Appropriate Technology, through a grant from the Rural Business-Cooperative Service, U.S. Department of Agriculture. These organizations do not recommend or endorse products, companies, or individuals. NCAT has offices in Fayetteville, Arkansas (P.O. Box 3657, Fayetteville, AR 72702), Butte, Montana, and Davis, California.
  2. 2. 2004. Since company ownership, media formu- COMMERCIAL BLENDS lations, and available products can change withOrganic producers who choose not to mix their time, you should ask questions to make sure youown growing media either purchase pre-pack- are getting an organically approved product.aged mixes or arrange with manufacturers tohave a mix custom-blended for them. The latteroption is occasionally chosen by large growers MAKING YOUR OWNand by groups of growers who pool their orders All good potting media should meet the needs ofto save money. Some enterprising growers order plant roots for air, water, nutrients, and support.more than they need and sell potting media as These needs will vary, however, depending ona sideline. the plant and its stage of growth. The technical details are beyond the scope of this publica-For those who buy off-the-shelf, finding appro- tion and can be found in standard horticulturalpriate growing media can be a challenge. Until literature and publications distributed by therecently, the market for organic seedling and pot- Cooperative Extension Service. A list of severalting media has been small, and few commercial information resources about growing media isblends have been readily available. Furthermore, in Appendix 2. Some of these focus on organicbecause of specific requirements of the National systems; others address conventional productionOrganic Standard, some familiar products may but contain basic and/or relevant longer be acceptable for certified production, Anyone who wants to produce consistent, high-because they contain prohibited ingredients. quality growing media should study and doOne good indication that a commercial product is detailed research.acceptable in organic production is a label stating Working from tried-and-true recipes is a goodthat the product is “OMRI Listed.” OMRI—the idea, especially at the beginning. Appendix 3Organic Materials Review Institute (1)—is a features several recipes for organic media blends.nonprofit entity that evaluates products and Some of these recipes are found in publishedprocesses for the organic industry. OMRI Listed literature; others are from conference and work-products have been thoroughly reviewed and are shop handouts or notes with uncertain author-consistent with the requirements of the National ship. Experimentation is the only sure way ofOrganic Standard. knowing which blend or blends will work bestHowever, to be absolutely certain that a product is for a particular farm or crop.acceptable for organic use, read the label to learn When experimenting, begin by making smallthe ingredients. If any components of the mix are batches and give them a thorough evaluation.questionable, check with your certification agent The next step is largely logistical: assembling thebefore buying it. This publication discusses many components and equipment and finding spaceof the ingredients allowed in organic production, and labor for the mixing and storage. Storage canas well as those that are prohibited—or at least present its own challenges, especially prevent-suspect. ing contamina-To help you lo- tion by weedcate commer- seeds.cial sources of Contrary togrowing media what someand some of the critics say, or-main ingredi- ganic growersents, there is a are permittedlist of commer- to use a widecial sources in array of mate-Appendix 1. rials in grow-This list was as- ing media.sembled in the © 2004 The challengespring of 2001 is more a mat-and updated in ter of ensuringPAGE 2 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  3. 3. consistent quality of ingredients than in finding nutrients, and can be made right on the farm.enough of them. The section that follows featuresa brief description of some of the materials com- The quality of compost depends in part on how itmonly used in organic growing media and dis- is made, but especially on what it is made from.cusses some of the issues that surround them. The variability of commercial compost is one of the main reasons it is less common in commer- cial organic media. Lack of availability is also a INGREDIENTS ALLOWED IN ORGANIC common problem. POTTING MEDIA Experienced compost makers know that compost quality is directly affected by the raw ingredients. If the feedstocks are low in nutrients, the resulting compost will also be nutrient-poor. To produceSoil. For many years, the trend in conventional a high-quality, media-grade compost, it is a goodgrowing has been toward soilless media. A major idea to make it according to a recipeusing areason for this is concern about soil-borne plant specific blend of balanced ingredientsratherdiseases and the excessive density of mixes where than simply using whatever feedstocks come tosoil is a dominant ingredient. However, soil is hand. The end product will be more consistentstill used in some organic blends. and better-suited for blending with peat andClean commercial topsoil is an acceptable natural other components.ingredient, but you have to be certain that it has According to one source (2), premium compostnot been treated with prohibited ingredients to for nursery mixes should have:kill microbes and weed seeds. • pH of 6.5 to 8.0 Check the label or ask the supplier to be sure. If • no (or only a trace of) sulfidesyou are using soil from a farm or garden, use only • <0.05 ppm (parts per million) ammoniathe best. Consider solarizing, steam pasteuriza- • 0.2 to 3.0 ppm ammoniumtion, or oven heating if the soil has any history • <1 ppm nitritesof soil-borne diseases. Microwaving is effective • <300 ppm nitratesfor pasteurization, but some certifiers might not • <1% CO2allow it. Soil contaminated with pesticides, pro- • moisture content of 30 to 35%hibited fertilizers, or environmental pollutants • >25% organic mattermay not be used. Certifiers might require that • <3mmhos/cm soluble saltsany soil used must come from land in certifiedorganic production. When making compost for media, plan at least six months in advance of when it will be needed.Sand. Sand in a growing mix can make a differ- For spring transplants, compost should be madeence. Coarse sand—called builder’s sand— is the previous summer and allowed to age throughbest. It adds air spaces to the potting mix. Avoid the fall and winter. Composting is not difficult,plaster sand and other fine sands. They tend to but it does require some experience and a vari-settle into the spaces between the other ingre- ety of clean, organically acceptable components.dients and make a dense mix. Clean, washed Animal manures and bedding, farm and gardensand has a near-neutral pH and little if any food waste, grass and alfalfa hay, and other materialsvalue for plants. Sand is much heavier than any can be combined to make a high-quality, reason-other ingredient used in potting mixes. The ably consistent compost. Organic amendmentsadded weight is good for tall, top-heavy plants such as greensand and rock phosphate can bethat might blow or tip over, but it is not the best added during the composting process to increasechoice for plants that will be shipped or moved a nutrient content. Protein-rich sources such aslot. Sand is the least expensive and most readily alfalfa and seed meals can also be included, if ad-available larger-particle material. ditional nitrogen is needed. While most compostCompost. Compost is perhaps the most common will provide adequate amounts of phosphate,potting-mix ingredient among organic producers. potash, and the necessary micronutrients, nitro-Cheaper than traditional components such as gen has proved to be the most variable elementpeat moss, compost holds water well, provides and the most important to manage. // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 3
  4. 4. Compost is rarely used alone as a potting me- closed facilities. The reason appears to be thedium. Most composts are too porous and the abundance of microbial species found in thesoluble salt levels are often high. Rynk (3) rec- natural environment.(7) For in-depth informa-ommends 20 to 30% compost content in potting tion on this topic, ask for ATTRA’s publicationmixes. Growers may use up to 50% in mixes for Disease Suppressive Potting Mixes. For more in-larger vegetable transplants.(4) formation on composting, ask for the Farm-Scale Composting Resource List.In many circumstances, compost can suppressplant disease. Israeli researchers discovered that Composted pine bark. Composted pine barkvegetable and herb seedlings raised in a mix of has a high lignin content, making it slow to de-40% vermiculite, 30% peatmoss, and 30% composted C M OMPOST AND ANURE ULES Rcow manure grew faster,with less incidence of dis- The National Organic Standard is very explicit about compost making.(8)ease, than those raised in a Compost piles must maintain a temperature between 131 and 170°F40% vermiculite/60% peat for at least three days in a static or enclosed vessel system, or at leastmoss mix.(5) To understand 15 days in a windrow system, with at least five turnings. Unless thesehow compost suppress- criteria are met, the resulting product is not—in the eyes of the Nationales disease, it is helpful to Organic Program—considered compost. Rather, it is simply a pile ofknow how plant substances raw materials. If one of those raw materials is manure, it can make a bigare broken down during the difference in how it may be used in crop production.composting process. Com-post goes through three Raw livestock manure can carry pathogens that pose a danger to humanphases. During the first health. The principal reason behind the NOP-approved process forphase, temperatures rise composting is to prevent possible food contamination with these organ-to 104 to 122°F and materi- isms. Maintaining high temperatures in the compost pile kills off mostals that degrade easily are microorganisms that are pathogenic to humans, and the resulting materialbroken down. In the sec- is believed safe to use on crops at any stage up through harvest.ond phase, temperaturesare between 104 and 149°F,and substances like cel- Heat-treated, dried, and other processed manures, and manure that haslulose are destroyed. Also not been composted according to NOP specifications, may still be useddestroyed in this phase are in organic crop production. However, it must be applied as if it were rawplant pathogens and weed m anure. According to the NOPs rules (9), raw manure:seeds, and (unfortunately)some beneficial biologi- • can be applied at will to crops not intended for human consumptioncal-control organisms arealso suppressed. The third • cannot be applied to a crop within 120 days of harvest if the ediblestage is the curing phase, portion has direct soil contactwhen temperatures beginto fall. It is during this • cannot be applied to a crop within 90 days of harvest when the ediblephase that humus content portion does not have soil contactincreases and some benefi-cial organisms—like Strep- We believe that these restrictions will be strictly enforced. Among thetomyces, Gliocladium, andTrichoderma, which serve as growers most at risk of manure rule violations are those that use organicbiocontrol agents—re-colo- media for direct greenhouse production of salad greens, edible flowers,nize the compost.(6) This and baby vegetables, because the time from seeding to harvest is is some- This specialty market is a significant one for many organic producers,what random. For example, and serious errors can result in a loss of certification, bad publicity, andcomposts produced in the even endangerment of public near a forest are moreconsistently suppressivethan those produced in en-PAGE 4 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  5. 5. grade. Bark lightens the mix, increases air space, Growers may have concerns about the rare butand decreases water-holding capacity. It may be serious disease called Cutaneous sporotrichosis.substituted, in part, for peat moss. Rynk specifi- Also known as “sporo,” this is a fungal infectioncally recommends it as a component in blends for that can be contracted through cuts and scratchespotted herbaceous and woody ornamentals.(3) in the skin while handling sphagnum moss—theComposted pine bark appears to impart some living moss that grows on top of a sphagnum bogdisease resistance.(10) Its pH is generally 5.0 to and is used in the floral industry to line wire bas-6.5, and it is low in soluble salts. Mixes using kets and make wreaths. Living sphagnum mosscomposted pine bark will probably require more is removed prior to the harvest of the underlyingnitrogen supplementation. sphagnum peat, which is dead material and no longer supports or harbors the fungus. ThereSphagnum peat moss and other forms of peat. is no hazard of contracting Cutaneous sporotri-Sphagnum peat moss is the most commonly used chosis through the handling of sphagnum peatsoilless medium, because it is widely available moss.(11)and relatively inexpensive. Peat moss is a verystable organic material that holds a great deal ofwater and air and does not decompose quickly.Peat moss is quite acidic (pH 3.5 to 4.0); limestoneis commonly added to the mix to balance the pH.Younger, lighter-colored peat moss does a betterjob of providing air space than does older, darkerpeat that has few large pores.Organic growers should be cautious when pur-chasing peat moss. Many commercial sourcesare treated with wetting agents. Since all but avery few of the commercial wetting agents areprohibited in organic production, assume thatany product with an unspecified wetting agentis prohibited. A few suppliers of untreated peatmoss are listed in Appendix 2.Other forms of peat can be used in growingmedia, though not all are readily found in themarketplace. Sphagnum peat moss—discussedhere—is the most common peat and representsits least-decomposed form. Light, dark, and blackpeats typically describe the same substance invarious stages of decomposition; darker peatsare more advanced in decomposition than lighterones. There are also some differences in theoriginal vegetation that decomposed to make thepeat. Besides the peat formed by decomposedsphagnum moss, other peats come from reeds,sedges, and grasses. Reed sedge peat is typicallyvery dark or black and does not have visible peatfibers. It is very difficult to rewet when driedand readily “fixes” phosphate. While the darkergrades are more commonly used for amendinghorticultural soils, some potting blends still usethem. Any type of peat will work in mixes, butexpect different results with each. Blending ofdifferent types of peat is done quite often. Photo by Jeff Vanuga ©NRCS 2004 // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 5
  6. 6. Coir. Coir dust, a mixture of short and powderfibers, is a by-product of the coconut fiber indus- QUESTIONS ABOUT PEATtry. Most coir comes from India, Sri Lanka, thePhilippines, Indonesia, and Central America.(16) HARVESTINGIt looks like sphagnum peat but is more granular The journal New Scientist reports that 455 bil-and does not contain twigs or sticks.(17) Coir lion tons of carbon are sequestered in peat bogshas a pH of 5.5 to 6.8 and usually contains higher worldwide. That is equivalent to about 70 yearslevels of potassium, sodium, and chlorine thanpeat.(18) Coir lasts two to four times longer than of industrial emissions, making conservation ofpeat, but it is more expensive, mainly because of peat bogs as important an issue as saving theshipping costs.(18) Coir is typically shipped in rainforests.(12) Much of the peatland in Europecompressed bricks, which expand when wetted. has already been exploited and destroyed, inIt is easier to wet than peat because there is no good part to provide fuel for power plants.(13)waxy cutin to repel water.(17) It also has a greater Therefore, concerns about the sustainability ofwater-holding capacity than peat. peat harvesting in North America are certainly justified.In a study performed in the mid-1990s at IowaState University, researchers found that petunias The source of the harvested peat is the firstand marigolds planted in a mix of 80% coir and factor in assessing the problem. Sphagnum20% perlite grew both taller and heavier.(19) peat moss appears to be the least threatened at the moment. Most sphagnum peat comes from 40,000 acres of bogs in Canada. These bogs are extensive, and less than 1% of the total is harvested annually. Within five years after a section is harvested, the peat moss is growing again, and the bog is restored to a functioning peatland.(15) However, peat bogs grow at the rate of only one millimeter per year (13), and increased demand from Europe may encourage more extensive harvesting. In the U.S., 17 states produce peat, includ- ing Alaska, Florida, Michigan, and Minnesota.One distributor recommends a mix of three parts About 81% of the U.S. production is reed-coir to one part compost.(8) Another offers a sedge peat (14), which is usually harvested fromproduct that contains 35 to 45% coir blended with marshes, mountain fens, and other sensitivepeat moss, vermiculite, and pine bark.(18) wetlands. The environmental impact and sus- tainability of reed-sedge peat harvesting as it isThere are a few cautions when using coir. Supple- now practiced is certainly questionable.(15)mental fertilization with potassium may need tobe cut back and nitrogen increased. There is alsothe possibility of salt damage.(20) Salt water iscustomarily used in the processing of some coir ume of the mix. Avoid the inclusion of glossyfiber and it is important to purchase only low-salt paper or paper with colored inks, as these arecoir products. It is also wise to ask whether any prohibited.prohibited wetting agents or binders have beenadded to any commercial product. Some coir Alfalfa. Alfalfa may be a good locally-availablesuppliers are listed in Appendix 1. alternative to peat moss. Alfalfa provides nu- trients—especially nitrogen—that are releasedNewspaper. Ground-up newspapers can be used slowly. Raw alfalfa must be processed before useas a substitute for peat moss in growing media. in growing media. Dried alfalfa is ground andNewsprint should not be more than 25% by vol- passed through a 2-cm screen. Water is addedPAGE 6 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  7. 7. ratio with peat moss can be a suitable replacement for bark.(21) Sawdust. The quality of saw- dust used as media depends on the wood. Cedar, walnut, and redwood sawdusts can be toxic to plants. Oak, hick- ory, and maple are reputed to tie up soil nitrogen more readily than sawdust from evergreens. Sawdust from treated or painted lumber is not allowed in organic pro- duction. Clay. Several Canadian stud- ies have shown that adding marine glacial clay (a non- swelling mica clay) to saw- dust significantly increases the size of greenhouse-grown cucumbers and increases the size and flowering of im- Kenaf (Hibiscus can- patiens and geraniums.(22) The researchers tested up to nabinus) is a fibrous 42.8 grams of clay per liter plant grown in warm- of sawdust. At North Caro- er regions of the U.S. lina State, investigators also found that adding arcillite—a Portions of the plant calcined montmorillonite are used to make pa- and illite clay— to pine bark per, and the waste increased the growth of coto- neaster.(23) products can be used©ARS 2004 in growing media. Perlite. Perlite is a volcanic rock that is heated and ex- panded to become a light- weight white material. It is sterile and pH-neutral. When added to a soiland the alfalfa is allowed to decompose for 20 mix, perlite can increase air space and improvedays. It is then air-dried for another 20 days water drainage. It is a hard material that doesbefore use. not break apart easily. Perlite pieces create tinyKenaf. Kenaf (Hibiscus cannabinus) is a fibrous air tunnels that allow water and air to flow freelyplant grown in warmer regions of the U.S. Por- to the roots. Perlite will hold from three to fourtions of the plant are used to make paper, and the times its weight in water, yet will not becomewaste products can be used in growing media. soggy. It is much lighter than—and can be usedKenaf stalks contain two different fibers, bast instead of—sand.and core. The core material is most suitable as Vermiculite. Vermiculite is a micaceous minerala potting mix ingredient. Growers who have that is expanded in a furnace, forming a light-used kenaf have seen excellent results. Two weight aggregate. Handled gently, vermiculitegreenhouse studies conducted in 1993 and 1995 provides plenty of air space in a mix. Handledshowed that coarse-grade kenaf core in a 1:1 // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 7
  8. 8. roughly, vermiculite compacts and loses its substrates is usually quite low. The base ingre-ability to hold air. Vermiculite holds water and dients of the growing media may also influencefertilizer in the potting mix. It also contains cal- the choice of fertilizers to be added. Fertilizerscium and magnesium and has a near-neutral pH. that are slowly available may be a poor choiceVermiculite comes in different grades. Medium in blends that lack the active microbial complexgrade is usually used for starting seeds. A coarse found in good compost or rich garden soil. Also,grade can be used in soil mix for older plants. many organic fertilizers have a significant effect on pH, and adjustments may need to be made in VERMICULITE AND ASBESTOS that regard. During the summer of 2000, reports began to Table 1 features a number of the more common surface warning of asbestos contamination in organic fertilizers that can be added to grow- ing media. Several characteristics are noted for vermiculite. Most of the nation’s vermiculite some of these products, where that information originates from a mine near Libby, Montana, is known. where the ore naturally contains about 2 to 3% asbestos fibers. Apparently, all sources of For more information on these fertilizers and oth- natural vermiculite contain some level of as- er alternatives, ask for ATTRA’s Alternative Soil bestos.(24) The principal danger comes from Amendments. To locate sources, see the Sources of inhaling the asbestos fibers, which are known Organic Fertilizers and Amendments resource list. carcinogens. As of July 2001, there has been no action by the federal government to recall, regulate, or enforce safety labeling on vermiculite products. The Environmental Protection Agency, however, has advised commercial growers to find substi- tutes for vermiculite in potting media.(25) If vermiculite must be used, work with it only in well-ventilated areas, wet the material as soon as possible, and blend it with materials that help reduce dust levels. Wear a dust mask and gloves as added protection. Asbestos contamination has not yet made vermiculite a prohibited substance in organic production, but that is a possibility in the future. Until that time, each producer should weigh the risks before using this material.Limestone. Calcium carbonate (CaCO 3) andcalcium magnesium carbonate (called dolomiticlimestone) are natural forms of lime that are usedto adjust pH and provide nutrients. Many otherlime products—burned (CaO) and slaked limes(CaOH)—are prohibited. Lime should be wellground for use in growing media.Alternative Fertilizers. Various organic fertiliz-ers are often used in media. This is especially im-portant in blends that contain little or no compostor soil, since the nutrient content of most otherPAGE 8 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  9. 9. Table 1. A Selection of Organic Fertilizers for Use in Growing Mediaa Rate of Nutrient Fertilizer Material Estimated N-P-K Release Salt and pH Effects Alfalfa Meal 2.5 0.5 2.0 Slow Blood Meal 12.5 1.5 0.6 Medium-Fast Bone Meal 4.0 21.0 0.2 Slow Cottonseed Mealb 7.0 2.5 1.5 Slow-Medium Tends to acidify Crab Meal 10.0 0.3 0.1 Slow Feather Meal 15.0 0.0 0.0 Slow Fish Meal 10.0 5.0 0.0 Medium Granite Meal 0.0 0.0 4.5 Very Slow Greensand 0.0 1.5 5.0 Very Slow Bat Guano 5.5 8.6 1.5 Medium Seabird Guano 12.3 11.0 2.5 Medium Kelp Meal 1.0 0.5 8.0 Slow Possibly high-salt Dried Manure Depends on Source Medium Possibly high-salt Colloidal Phosphate 0.0 16.0 0.0 Slow-Mediumc Rock Phosphate 0.0 18.0 0.0 Very Slow-Slowc Soybean Meal 6.5 1.5 2.4 Slow-Medium Wood Ash 0.0 1.5 5.0 Fast Very alkaline, salts Worm Castings 1.5 2.5 1.3 Medium(a) Information in the table has been adapted primarily from Penhallegon, Ross. 1992. Organic fertilizer NPK values compiled. In Good Tilth. January. p. 6.; and Rodale Staff. 1973. Organic Fertilizers: Which Ones and How To Use Them. Rodale Press, Emmaus, PA. p. 50.(b) Cottonseed meal from many sources may be too contaminated by routine pesticide use to be permitted in certified production. Growers should consult their certifiers before using.(c) The availability of phosphorus in different forms of rock phosphate depends on the pH of the mix, biological activity, fineness of grind, and the chemical composition of the source rock. Precise performance is not easy to predict. // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 9
  10. 10. 3) Rynk, Robert (ed.). 1992. On-Farm Mad Cows and Potting Mixes Composting Handbook. Publication NRAES-54. Northeast Regional Bovine Spongiform Encephalopathy (BSE), or Agricultural Engineering Service, Cornell “Mad Cow Disease,” is a fatal brain disorder Cooperative Extension, Ithaca, NY. p. 81. that can infect humans, where it is recognized as Creutzfeldt-Jakob Disease (CJD)—a devastating 4) Brown-Rosen, Emily. 2001. Organic illness. According to authorities, BSE is not a Materials Review Institute. November. problem in the United States.(26) However, Personal communication. the fear of BSE and CJD has prompted the De- 5) Williams, Greg, and Pat Williams. 1998. meter Association—which certifies Biodynamic Compost as a substitute for peat in seedling farms—to completely prohibit the use of bone grow mix. HortIdeas. December. p. 137. meal and blood meal, since these could be avenues of infection for BSE.(27) 6) Rynk, Robert (ed.). 1992. On-Farm Composting Handbook. Publication NRAES-54. Northeast Regional Blood meal, bone meal, and other animal Agricultural Engineering Service, Cornell by-products are permitted in certified or- Cooperative Extension, Ithaca, NY. ganic production as soil amendments, though p. 6−13. they cannot be fed to organic livestock. As a precaution, dust masks and gloves should 7) Hoitink, H.A.J., Y. Inbar, and M.J. Boehm. be worn when handling these materials. 1991. Status of compost-amended potting mixes naturally suppressive to soilborne diseases of floricultural crops. Plant Disease. September. p. 869–873. SUMMARY 8) Terms Defined—Compost. §205.2 of theConventional growing media that contain syn- National Organic Program Final Rule.thetic wetting agents and standard fertilizers be used in organic production of field Final%20Rule/regtext/reg-definition.htmtransplants, container plants, and greenhouse 9) Soil fertility and crop nutrient managementcrops. Acceptable growing media can be com- practice standard. §205.203(1) of thepounded from a wide variety of approved ma- National Organic Program Final Rule.terials. These organic blends may be purchased, custom-blended by manufacturers, Final%20Rule/regtext/reg-production.htmor produced on-farm. 10) Ferry, Shannen, et al. 1998. Soilless media: practices make profit. Greenhouse Grower. REFERENCES July. p. 28, 33–34, 36. 11) Relf, Diane. 1996. Sphagnum moss1) The Organic Materials Review Institute vs sphagnum peat moss. Virginia (OMRI) Cooperative Extension, Blacksburg, VA. Box 11558 August. Eugene, OR 97440-3758 541-343-7600 articles/misc/sphagnum.html 541-343-8971 FAX 12) Sadowski, I.E. 2001. Doing the peat bog two-step. Mother Earth News. June−July. p. 18.2) Shirley, Christopher. 1995. Profit making compost. The New Farm. January. p. 20, 13) Grohmann, Sissi. 2002. Peat bogs: 22–26, 47. preservation or peril? Permaculture Activist. May. p. 23–27.PAGE 10 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  11. 11. 14) Byczynski, Lynn. 2003. Should you use Encephalopathy (BSE). West Virginia peat in the greenhouse. Growing For University, Cooperative Extension. Market. January. p. 11–12. q_a.htm15) Fowler, Veronica. 1999. Peat harvesting: sustainable or not? National Gardening. 27) Anon. 2000. Guidelines and Standards March–April. p. 28. for the Grower for Demeter Biodynamic Certification and In-Conversion-To-16) Nelson, Josh. 1998. Coconuts to the rescue. Demeter. Demeter Association, Aurora, Organic Farms, Folks & Foods (Published NY. p. 8. by NOFA-NY). July–August. p. 8–9.17) Hulme, Fred, Rick Vulgamott, and Rick Vetanovetz. 1999. The evolution APPENDIX 1 of growing mix components. GMPro. Sources of Organic Potting Media, September. p. 65, 67–69, 71. Untreated Peat Moss, Coir, and Other Approved Ingredients18) Anon. 1999. Going coconuts. Ecological Landscaper. Winter. p. 12. It bears repeating: Organic producers should always consult their certification agents before purchasing19) Evans, Michael R., and Robert H. Stamps. brand name products, especially those with unfamiliar 1996. Growth of bedding plants in ingredients. sphagnum peat and coir dust-based substrates. Journal of Environmental Beautiful Land Products Horticulture. December. p. 187–190. P.O. Box 179 West Branch, IA 5235820) Van Meggelen-Laagland, Incke. 1996. 800-227-2718 Coir media: the newest peat substitute? 319-643-7368 FAX GrowerTalks. August. p. 96, 98, 103. blp@beautifullandproducts.com21) Webber, Charles L. III, Julia Whitworth, and John Dole. 1998. Kenaf core as a Web site states that all potting media potting mix component. meets criteria for organic certification. 97/0000079779.html Cashton Farm Supply 199 Front Street22) Ehret, David L. et al. 1998. Clay addition Cashton, WI to soilless media promotes growth and 608-654-5123 yield of greenhouse crops. HortScience. February. p. 67–70. www.cfspecial.com23) Warren, S.L., and T.E. Bilderback. 1992. Long-time supplier of products to organic Arcillite: effect on chemical and physical farmers. Sells sphagnum peat moss and potting properties of pine bark substrate and soil for organic production. Mail order avail- plant growth. Journal of Environmental able. Horticulture. Vol. 10. p. 63–69. Coconut Palm Resources, Inc.24) Anon. 2001. Asbestos in vermiculite. 2459 SE T.V. Hwy. B.U.G.S. Flyer. March. p. 6−7. Hillsboro, OR 9712325) Byczinski, Lynn. 2001. Safety of 503-649-8101 vermiculite still in question. Growing for 503-259-0573 FAX Market. July. p. 9, 14. www.coconutpalmresources.com26) Barringer, Sam. No date. Mad Cow Disease Information: Questions and Supplies organic coir under the Cocolife™ label. Answers About Bovine Spongiform Assures that product is not processed in salt // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 11
  12. 12. water. www.johnnyseeds.comCrystal Company Long-time supplier to organic producers. 572 Leffingwell Organic soil mixes. St. Louis, MO 63122 314-966-5999 Lambert Peat Moss, Inc. 106 Lambert Rd. Supplier of coir. Riviere-Ouelle, QB G0L 2C0 CanadaFafard 418-852-2885 P.O. Box 790 800-463-1313 Agawam, MA 01001 418-852-3352 FAX 800-732-8667 413-789-3425 FAX Produces OMRI Listed peat moss products: Jeff’s Natural Solution, Ferti-Lome Pure Produces a series of organic mixes labeled FOF Canadian, Lambert Canadian, and Canadian (Fafard Organic Formulas) to match their Gold. traditional products. Modugno-Hortibec, Inc.Farm Wholesale Greenhouses 5800 Kiernan 3740 Brooklake Road NE Montreal, QB Salem, OR 97303 H4S 2B5 Canada 800-825-1925 514-336-6226 800-565-7645 514-336-0404 FAX Supplier of CocoLite™ husks and bricks. www.modugno-hortibec.comGreen Technology Group P.O. Box 7268 Produces five OMRI Listed transplant media Arlington, VA 22207 products under the Nature Mix label. 703-533-1970 Okanagan Pride Garden Products, Inc. 703-832-0497 FAX P.O. Box 42014 Winfield, BC www.greentg V4V 1Z9 Canada 250-766-1123 Manufactures GrowPro transplant medium; 250-765-8639 FAX OMRI listed. worms4us@telus.netGrowing Success P.O. Box 94 West Kingston, RI 02892 Produces Nurturing Nature peat moss and 401-782-8747 several worm casting products. OMRI Listed. 401-295-2770 FAX Peaceful Valley Farm Supply P.O. Box 2209 Coir products. Claims “low to non-existent” Grass Valley, CA 95945 detectable salt content. 530-272-4769Johnny’s Selected Seeds 888-784-1722 955 Benton Ave. Winslow, ME 04901 207-861-3900 Long-time supplier to the organic community.PAGE 12 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  13. 13. Distributes Coco Peat and a variety of organic 540-651-3228 FAX potting soils. www.7springsfarm.comPeaco Peat Moss & Soils Box 67 Carries McEnroe Organic Farm growing mixes. Big Arm, MT 59910 Catalog claims these meet NOP requirements 406-849-5729 for organic production. Also carries asbestos- 800-829-0729 free vermiculite and perlite. 406-849-5779 FAX Star Nursery 125 Cassia Way Manufactures Peaco All Natural Organic Henderson, NV 89014 Potting Soil. OMRI Listed. 702-568-7000 866-584-7827Premier Horticulture 702-568-7001 FAX 127 S. Fifth St., Ste. 300 Quakertown, PA 18951 215-529-1290 Manufactures OMRI Listed Dr. Q’s Filthy 800-525-2553 Rich Potting Soil and Paydirt Premium 215-529-1288 FAX Planting Mix. Sun Gro Horticulture, Inc. 15831 NE 8th St., Ste. 100 Manufactures Pro-Mix Ultimate Organic Mix. Bellevue, WA 98008 OMRI Listed. 425-450-9379, 373-3614, 373-3605 888-982-4500 (central region)Premier Tech, Inc. 425-641-0190 FAX 1 Avenue Premier Riviere-du-Loup, QB G5R 6C1 Canada 800-606-6926 Sun Gro manufactures about 20 different 418-862-6642 FAX OMRI Listed transplant media products. Most are marketed under the Sunshine, Sunny Grower, Alberta Rose, or Black Gold labels. Two OMRI Listed transplant media products, Superior Peat, Inc. marketed under the Myke label. 1700 Carmi Avenue Penticton, BC V2A 8V5Schultz Co. Canada 2150 Schuetz Rd. 250-493-5410 St. Louis, MO 63146 250-493-4475 FAX 314-683-2751 800-242-1166 314-253-5907 FAX OMRI Listed products include Superior Peat Black Peat and Superior Peat Peat Moss. Has two OMRI Listed transplant media Vermont Compost Company products, marketed under the Garden Safe label. 1996 Main St. Montpelier, VT 05602Seven Springs Farm 802-223-6049 426 Jerry Lane, NE. Floyd County 802-223-9028 FAX Check, VA 24072 540-651-3228 // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 13
  14. 14. printed by Oliver & Boyd, London. Product brochure claims that all products are acceptable for organic production. Includes Order from Oliver & Boyd, 39A several potting mixes, composted manure, Welbeck Street, W.1, London, England. sphagnum, vermiculite, perlite. —For Specialized Information on OrganicVgrove, Inc. Potting Media— 111 Fourth Avenue, Ste. 371 St. Catherines, ONT L2S 3P5 The New Organic Grower. 1995. By Eliot Canada Coleman. Chelsea Green Publishing Co., 905-687-1877 White River Junction, VT. 340 p. (Chapter 905-687-8635 FAX 14 is especially useful.) OMRI Listed product: Millenniumsoils Coir. Available for $28 postage-paid from: Acres USAWestern Industrial Clay Products P.O. Box 91299 724 E. Sarcee St. Austin, TX 78709 Kamloops, BC V2H 1E7 800-355-5313 Canada 512-892-4448 FAX 250-372-1600 250-372-3777 FAX The Organic Gardener’s Home Reference. 1994. By Tanya Denckla. Storey Communications, Pownal, VT. 274 p. (Chapter 1 is especially useful.) Has two OMRI Listed transplant media products marketed under the Garden Listed for $14.99. Available through most Treasure label. bookstores and on-line at Organic Transplant Production for the APPENDIX 2 Advanced Market Gardener. This was the title of a workshop given by Dr. JohnRecommended Guides for Learning Biernbaum, Michigan State University, and Chris Blanchard, Rock Spring Farm, Spring Grove, Minnesota. It was presented March to Make Potting Media 2001 as part of the Organic University program offered by the Midwest Organic and Sustainable Education ServiceFor General Information on Potting Media (MOSES) in conjunction with its Upper Midwest Organic Conference. ParticipantsGrowth Media for Container Grown were provided with an excellent manual. Ornamental Plants. Revised edition. MOSES plans to continue offering the Extension Bulletin 241. By Dewayne University program and should be Ingram, Richard Henley, and Thomas contacted regarding scheduling and Yeager. 1993. 21 p. Published by the availability of the manual. Contact: University of Florida, Gainesville, FL. MOSES P.O. Box 339 This publication can be downloaded from Spring Valley, WI 54767 Not available in 715-772-3153 hardcopy except as single copies to Florida residents via Cooperative Extension. The Fruit, The Seed, and The Soil. John Innes Sustainable Vegetable Production from Start- Leaflets #1−9. By W.J.C. Lawrence. 1948. up to Market. 1999. By Vernon Grubinger. Published by the John Innes Horticultural Cornell Cooperative Extension, Ithaca, NY. Institution, Bayfordbury, Hertford, UK;PAGE 14 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  15. 15. 268 p. (Contains sections on composting Organic substitute for Cornell Mix and on transplant production.) Available for $42 postage-paid from: ½ cu. yd. sphagnum peat NRAES ½ cu. yd. vermiculite 152 Riley-Robb Hall 10 lbs. bonemeal Ithaca, NY 14853 5 lbs. ground limestone 607-255-7654 5 lbs. bloodmeal 607-254-8770 FAX The following four recipes were found in theGrowing 101 Herbs That Heal. 2000. By March−April 1989 issue of the Ozark Organic Tammi Hartung. Storey Books, Pownal, Growers Association Newsletter. The formulas VT. 256 p. (Includes author’s favorite are credited to the Farm and Garden Project at potting mix for starting herbs. Organic the University of California—Santa Cruz. production.) Seedling mix for styrofoam seedling flats Listed for $24.95. Available through most 2 parts compost bookstores and on-line at 2 parts peat moss 1 part vermiculite, pre-wet APPENDIX 3 Sowing mix Recipes for Growing Media 5 parts compostThese recipes come from a variety of sources 4 parts soiland present a wide range of options for working 1–2 parts sandwith organically acceptable materials. Because 1–2 parts leaf mold, if availablethe sources are diverse, units of measurement 1 part peat moss, pre-wet and sifted.are also different. When the origin of a recipe isknown, or further details and recommendations Note: All ingredients are sifted through a 1/4-inchare known, they have been provided. Note that screen. For every shovelful of peat, add two table-several recipes are intended for use with Lad- spoons of lime to offset the acidity.brooke “soil blockers.” Soil blockers are handtools designed to form free-standing blocks of Prick-out mix for growing seedlings to trans-potting soil, which serve as a substitute for peat plant sizepots, seedling flats, etc. The system has been 6 parts compostpopular among small-scale producers. One 3 parts soilsource of soil blockers is Peaceful Valley Farm 1–2 parts sandSupply, P.O. Box 2209, Grass Valley, CA 95945, 1–2 parts aged manureTel: 530-272-4769. 1 part peat moss, pre-wet and siftedThe first recipe shown is a classic soil-based for- 1–2 parts leaf mold, if availablemula; the second is a soilless recipe based on the 1 6” pot bone mealCornell Mix concept. Special potting mixClassic soil-based mix 1 wheelbarrow-load sifted soil1/3 mature compost or leaf mold, screened 1 wheelbarrow-load aged manure1/3 garden topsoil 1 wheelbarrow-load sifted old flat mix1/3 sharp sand 5 shovelfuls sifted peat 2 4” pots bone mealNote: This mix is heavier than modern peat mixes, 2 4” pots trace mineral powderbut still has good drainage. Compost promotes 2 4” pots blood meala healthy soil mix that can reduce root diseases.Vermiculite or perlite can be used instead of sand. The following recipes are taken from John Jeav-Organic fertilizer can be added to this base. // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 15
  16. 16. ons’s How to Grow More Vegetables…, Ten Speed The following four recipes are credited to EliotPress, Berkeley, CA. Coleman. The first was published in the Winter 1994 issue of NOFA-NJ Organic News, in an articleClassic planting mix by Emily Brown-Rosen. The remaining three areOne part each by weight: adapted from Coleman’s book The New Organiccompost (sifted, if possible) Grower (see Appendix 2).sharp sand Organic potting mixturf loam (made by composting sections of turfgrass grown in good soil) 1 part sphagnum peat 1 part peat humus (short fiber) 1 part compostNote: the mixture should be placed in growing flats 1 part sharp sand (builder’s)on top of a 1/8-inch layer of oak leaf mold to providedrainage. Crushed eggshells should be placed be- to every 80 qts. of this add:tween the leaf mold and compost for calcium-loving 1 cup greensandplants like cabbages and carnations. 1 cup colloidal phosphateSimple soil flat mix 1½ to 2 cups crabmeal, or blood meal ½ c. limeEqual parts by volume:compostbed soil (saved from a biointensive production Blocking mix recipebed during double-digging process) 3 buckets (standard 10-qt. bucket) brown peat ½ cup lime (mix well)The next three formulas are credited to the 1992 2 buckets coarse sand or perliteNOFA-NY Organic Farm Certification Stan- 3 cups base fertilizer (blood meal, colloidaldards. phosphate, and greensand mixed together in equal parts)Classic formula for horticultural potting mix 1 bucket soil 2 buckets compost1/3 mature compost or leaf mold, sieved1/3 fine garden loam Mix all ingredients together thoroughly. Cole-1/3 coarse sand (builder’s sand) man does not sterilize potting soils; he believes that damp-off and similar seedling problems are the result of overwatering, lack of air move-Sterile peat-lite mix ment, not enough sun, overfertilization, andshredded sphagnum peat moss 0.5 cu. yd. other cultural mistakes.horticultural vermiculite 0.5 cu. yd. Blocking mix recipe for larger quantitiesdried blood (12% N) 5 lbs.steamed bonemeal 10 lbs. 30 units brown peatground limestone 5 lbs. 1 /8 unit lime 20 units coarse sand or perliteRecipe for soil blocks ¾ unit base fertilizer (blood meal, colloidalblack peat with ½ cup lime 20 qts.; sand or phosphate, and greensand mixed together incalcined clay 20 qts.; regular peat with 1 cup of equal parts)greensand,1 cup of colloidal phosphate, and 1 10 units soilcup bloodmeal 20 qts.; soil 10 qts.; compost 10 20 units compostqts. Mini-block recipeNote: all bulk ingredients should be sifted through a½” screen. 16 parts brown peat ¼ part colloidal phosphate ¼ part greensandPAGE 16 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  17. 17. 4 parts compost (well decomposed) Growing mixes for pots and basketsNote: If greensand is unavailable, leave it out. Donot substitute a dried seaweed product in this mix. 30 percent topsoil 60 percent peatThe next recipe and details come from John 10 percent perliteGreenier, of Stoughton, Wisconsin. They were 5 pounds lime per cubic yardpublished in the January 1996 issue of Growing 3 pounds dolomitic lime per cubic yardfor Market. Note: The handling of this pot mix is the same asSeedling mix for soil blocks or seedling flats for pack mix.Sphagnum peat moss: 2 3-gal. bucketsLime: ¼ c.Fertility mix: 1½ cups The following recipes and instructions are fromColloidal (rock) phosphate: 2 cups a workshop entitled “Getting Started in Or-Greensand: 2 cups ganic Market Gardening,” which was offeredBlood meal: 2 cups as part of the March 2001 “Organic University”Bone meal: ½ cup program sponsored by Midwest Organic andKelp meal: ¼ cup Sustainable Education Services (MOSES) inVermiculite: 1½ buckets conjunction with its Upper Midwest OrganicCompost: 1½ buckets Conference. The first is credited to Tricia Bross, Luna Circle Farm, Gays Mills, WI; the second isDirections for mixing credited to Steve Pincus, Tipi Produce, Madi-1. Add peat to cement mixer or mixing barrel. son, WI.2. Spread the lime and fertility mix over the peat. Luna Circle recipe3. Mix these ingredients thoroughly.4. Add the compost and vermiculite and mix 2 buckets black peat (1 bucket = 8 quarts) well again. When done, examine the distri- 1/2 bucket compost bution of vermiculite to ensure that it has Fertility mixture: been mixed in evenly. 1 cup greensand 1 cup rock phosphateNote that all bulk ingredients should be screened 1 cup kelp mealthrough 1 /4-inch hardware cloth. Well matured, 2 buckets sphagnum peat mossmanure-based compost should be used (avoid poultry 1 bucket sandmanure and wood-chip bedding). 1 bucket vermiculite Directions for mixing: Screen the peat and the The next two recipes were published in the compost and combine with the fertility mix.September 1990 issue of Greenhouse Manager in Mix well. Add the sphagnum, sand, and ver-an article entitled “Recipes for Success in Media miculite. Mix well again.Mixes,” by Kathy Z. Peppler. Tipi Produce recipeGrowing mix for packs 2 bales sphagnum peat moss (3.8 or 4.0 cu.ft.40 percent topsoil bales)40 percent Canadian-type Michigan peat 1 bag coarse vermiculite (4.0 cu.ft. bags)20 percent perlite 1 bag coarse perlite (4.0 cu.ft. bags)5 pounds lime per cubic yard 6 quarts of a fertilizing mixture comprised of:3 pounds dolomitic lime per cubic yard 15 parts steamed bone meal 10 parts kelp mealNote: The topsoil and peat are sterilized early in 10 parts blood mealthe fall, then brought indoors to be blended with the 5−10 parts dolomitic limestone (80−90other ingredients and stored inside. mesh) // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 17
  18. 18. Note: This mix works well in small and medium plug 2 parts well-finished composttrays and 1020 flats for growing lettuce, onions, leeks, 2 parts good topsoilpeppers, tomatoes, melons, squash, cucumbers, and 1 part leaf moldmany flowers. When repotting small plugs into largercells, add about 1/3 by volume of old leaf mold or com-post and more fertilizing mixture. Continue to fertilize The remaining recipes in this appendix are oftwice per week with soluble fish and seaweed fertilizer. uncertain origin, but were published in earlier versions of ATTRA’s Organic Potting Mixes.The following three recipes are adapted from a Recipe #1subchapter entitled “Using compost for container 50 to 75 percent sphagnum peat mosscrops and potting mixes” in On-Farm Composting 25 to 50 percent vermiculiteHandbook, by Robert Rynk, (ed.). 1992. Publica- 5 lbs. ground limestone per cu. yd. of mixtion NRAES-54. Northeast Regional AgriculturalEngineering Service, Cornell Cooperative Exten- Recipe #2sion, Ithaca, NY. 186 p. 6 gallons sphagnum peat mossVegetable transplant recipe ¼ cup limeEqual parts by volume of: 4.5 gallons vermiculitecompost 4.5 gallons compostpeat moss 1½ cups fertility mix made of:perlite or vermiculite 2 cups colloidal (rock) phosphate 2 cups greensand ½ cup bonemealBedding plant recipe ¼ cup kelp meal25% compost50% peat moss Recipe #325% perlite or vermiculite 10 gallons sifted 2-year-old leaf mold 10 gallons sifted compostContainer mix for herbaceous and woody 5 to 10 gallons sphagnum peat mossornamentals 5 gallons perlite 5 gallons coarse river sandEqual parts by volume of: 2 cups bloodmealcompost 6 cups bonemealcoarse sandpeat moss or milled pine bark Recipe #4 40 quarts sphagnum peat moss 20 quarts sharp sandThe following two simple recipes came from 10 quarts topsoilMark Feedman, a practitioner of the Biodynamic- 10 quarts mature compostFrench Intensive system. The first mix was used 4 oz. ground limestonewith great success while doing development 8 oz. bloodmeal (contains 10% nitrogen)work in the Dominican Republic; the second is 8 oz. rock phosphate (contains 3% phosphorus)an adaptation used later in New Mexico. 8 oz. wood ashes (contains 10% potassium)Dominican Republic mix Recipe #5Equal parts:fine loam soil 9 quarts compostsharp horticultural sand 1 cup greensandwell-finished leaf mold 3 quarts garden soilNew Mexico mixPAGE 18 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION
  19. 19. ½ cup bloodmeal NCAT would like to acknowledge OMRI staff3 quarts sharp sand members Cindy Douglas, Brian Baker, and Em-½ cup bonemeal ily Brown-Rosen for their assistance in review-3 quarts vermiculite ing the original draft of this publication.Recipe #61 part peat1 part bonemeal1 part perlite1 part compost (or leaf mold)1 part worm castings (optional)Recipe #72 parts vermiculite3 parts peat2 parts perlite2 parts cow manure3 parts topsoil½ part bonemealRecipe #815 qts. screened black peat15 qts. brown peat17 qts. coarse sand14 qts. screened leaf compost3 oz. pulverized limestone9 oz. greensand¾ cup dried blood3 oz. alfalfa meal3 oz. colloidal phosphate9 oz. pulverized bonemealRecipe #910 pounds compost30 pounds sphagnum peat moss60 pounds white sand8 pounds calcium carbonate4 pounds soft rock phosphate2 pounds sawdustRecipe #1070 pounds white sand25 pounds sphagnum peat moss5 pounds chicken manure8 pounds calcium carbonate4 pounds soft rock phosphate // POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION PAGE 19
  20. 20. By George KuepperNCAT Agriculture Specialistand Kevin Everett, Program InternSeptember 2004©NCAT 2004Edited by Paul WilliamsFormatted by Ashley Rieske The electronic version of Potting Mixes for Certified Organic Production is located at: HTML PDF IP112 Slot #61 Version #092904PAGE 20 //POTTING MIXES FOR CERTIFIED ORGANIC PRODUCTION