Storage after arrival:
Before planting, rhizomes can be stored up to 4 weeks at 40-50⁰F. Be sure to keep them covered so they do not dry out.
Use a well-drained, sterilized planting medium. Ideal pH should be 6.5 and no lower. Plant 3 rhizomes per 4" pot; 4 rhizomes per 5" pot. Lay the corms (roots) flat and cover with 1/2" of soil medium. Fafard #2 and Metro Mix 350 are the best suited soils. Avoid any soil which contains bark. Can be placed pot to pot when grown on benches until leaves start, then space 8" on center.
Water the medium thoroughly, then only water the medium when it becomes dry and/or the plants begin to grow vigorously. DO NO OVERWATER.
Because oxalis grow fast, they need to have sufficient fertilizer. Use a complete NPK fertilizer on a weekly basis once the plants begin to grow vigorously. Either 200 ppm of 20-20-20 or 14-14-14 Osmocote can be used. If any chlorosis begins to appear in the oldest leaves, use a micronutrient foliage spray. If the foliage is yellowing this could be a nitrogen deficiency problem.
Use a medium light (2500-5000 ft. candle) intensity greenhouse that is well ventilated.
In order to assure proper germination, start Regnelli White at 68-75⁰F - Triangularis & Fanny at 72-78⁰F. The plants grow well in full sun or light shade at temperatures between 70-75⁰F. If grown at lower than 65⁰F or higher than 85⁰F the plants may suffer. If flowers bloom down in the foliage, the plant has probably been grown with too much shade. Once the plants show vigorous growth the temperature may be lowered to 65⁰F.
Height Control for Pots:
Height control - Bonzi drenches proved to be the most effective of all treatments for suppressing plant height in regnelli and triangularis. Sumagic drenches of 0.10 mg/pot were as effective as the Bonzi treatments in reducing the height of regnelli pink. The other concentrations of Sumagic did reduce the height in both varieties, but their effects were not as noticeable as were the Bonzi treatments. It was also determined that A'Rest should not be used on these species due to its cost and inactivity. Oxalis growers can use Bonzi drenches in the range of 0.05 to 0.1 mg/4 1/2" pot to "stop" further growth once a desired height is reached. Early drenching of Bonzi is to be avoided since this would probably cause severe stunting.
Oxalis are almost disease free, but will attract insects in warmer temperatures. The following product is advised for spiders - Pentac 50 wettable powder - 8 ounces per 100 gallons of water, 2 applications per week for two weeks.
Plants are ready to market when foliage is fully expanded. It is not necessary to have flowers present.
Bill Miller, "Production Tips and Height Control Techniques for Oxalis" Greenhouse Product News, 7:8, August, 1997, p.8