- Additional Plants: indigo (Indigofera suffruticosa)
- Crop Production: cropping systems, seed saving
- Education and Training: demonstration, workshop
- Farm Business Management: value added
- Pest Management: mulching - plastic
- Sustainable Communities: new business opportunities
Farmer Kathy McCullough of McCullough Farms in Kingstree, South Carolina received a 2017 SARE Producer Grant to demonstrate successful methods for growing indigo plants for use in indigo dye production. Her first growing season for indigo at the farm was 2015, when she and husband William McCullough grew several dozen plants known as Guatemalan indigo (Indigofera suffruticosa) in their fruit orchard. This is the same variety grown in the 18th century in the Lowcountry of South Carolina when indigo dye was manufactured on plantations and was a major export from Charleston to Europe. A small amount of indigo dye powder (< 5lbs) was produced from the 2015 crop in conjunction with Caroline Harper and David Harper of Chi Design Indigo, a small textile arts business based in Columbia, South Carolina.
Production was scaled up in 2016 and, with seeds saved from the 2015 crop, approximately 400 plants were grown on one-quarter of an acre. Two harvests were made to produce approximately 8 lbs of indigo dye powder.
With the 2017 crop, the SARE Producer Grant allowed Kathy McCullough to work with Caroline and David Harper in testing different methods for successful production of an indigo crop that was efficient to harvest and produced a strong blue dye powder. Methods included rows that were: 1) planted with plugs/seedlings and no weed fabric; 2) planted with plugs/seedlings with weed fabric; 3) direct seeded with no weed fabric; and 4) volunteer re-sprouts from the previous year's crop. Working primarily with seeds saved from the 2015 crop (many of the 2016 seeds were not viable), approximately 600 plants were grown on one-half an acre. The soil type for this field is Yemasee Sandy Loam (Ym), which is an outer coastal plain soil well-suited to growing this type of indigo. The crop was successful, with two harvests (September and October 2017) yielding abundant leaves and stems that were processed to produce 15.9 lbs of high-quality indigo powder. It was determined that the plugs/seedlings with weed fabric were the most efficient and productive method, though the volunteers/re-sprouts were lowest in maintenance. Chi Design Indigo uses dye from the 2016 and 2017 crops to produce a wide range of natural fiber homeware and personal fashion items which are sold primarily to customers in central and coastal South Carolina. A small amount of the dye is also used for indigo dyeing workshops and sold to natural dyers.
Indigofera suffruticosa plants must be planted using a system that allows for more efficient production and harvesting with less human labor – specifically with efficient, sustainable methods for weed control, fertilizing and harvesting, which currently make up the bulk of the hand labor. This system will be designed as a replicable model for application on farms throughout the South where Indigofera suffruticosa can be grown (generally warmer coastal areas of SC, GA, and northern FL).
Methods include: Indigo seed germination and growth of plugs/starts in flats protected from late-spring frost in April; disc cultivation and installation of weed fabric in May; transplanting of plugs/starts in the field into the weed fabric by hand by June; and managing of weed competition and natural fertilizer application during June, July and August. Initial plans to introduce selective/rotational grazing of a flock of Tunis sheep into strips of weeds/grasses growing between rows of the indigo crop as a biological method for weed control and fertilization were changed when the flock was sold and moved to another farm. Initial plans for using a sickle-bar mower to harvest the indigo crop were changed when it was determined that the height of the mower would take off too much of the top growth at one time. The harvest was completed with hand pruners, followed by bundling of indigo stems/leaves for immediate use in vats to produce dye.
This production system was tested at the McCullough Farm during the 2017 growing season, and its results quantified in terms of biomass production were shared with farmers, researchers, and natural dyers at a Harvest Day workshop in October 2017. The specifics of this system were then presented and shared as a replicable model for use on farms throughout the coastal counties of SC, GA, and northern FL. Indigo seed from this crop was distributed over the winter of 2017 to interested farmers, with the goal of increasing commercial production for use in on-farm dye production, and ultimately a commercial-scale dying facility being created in the Charleston area of SC.