Stevia, also known as the Sugar Plant, has leaves that are very sweet yet calorie-free. The active compounds responsible for the sweetness are the steviol glycosides (mainly stevioside and rebaudioside).
Apr 7, 2016 = Day 0. Plant started from seed (Park Seed Co.). Seeds sowed in 1.5-inch rockwool cube in 2-inch net-pot. Moistened with dilute fertilizer solution: 1.2 mL (1/4 tsp) Dyna-Gro Liquid Grow, 0.8 mL pH Down per gallon of tap water. Nutrient concentrations (in ppm): N 22, P 29, K 16, Ca 6, Mg 1.6, S 0.2, Fe 0.3, Mn 0.2, B 0.1, Zn 0.2, Cu 0.2, Mo 0.003, Ni 0.0003, Co 0.005. pH = 6.0.
Apr 11 = Day 4. Plant germinated, placed directly under a fluorescent light (2 ft. T8 bulb, 17W, 6500k) for 16 hours per day.
Apr 22 = Day 15. Installed plant into 3.5-gallon bucket. Hydroponic solution composed of 3.5 gal (13.2 L) tap water, 53 mL 250x Masterblend 4-18-38, 53 mL 250x calcium nitrate, 53 mL 250x magnesium sulfate, 0.7 mL Dyna-Gro Pro-TeKt, 3.5 mL pH Down. (This solution is equivalent to 3.5 gal water, 7 g Masterblend, 7 g calcium nitrate, 3.5 g magnesium sulfate). Nutrient concentrations (in ppm): N 103, P 95, K 202, Ca 100, Mg 29, S 34, Fe 2.1, Mn 1.1, B 1.1, Zn 0.3, Cu 0.3, Mo 0.05, Si 4. pH = 6.0. Plant moved to indoor grow room, receiving 8 hours LED grow light per day, plus 3 hours sunlight per day.
Jul 13 = Day 97. Entire plant was harvested, cut at the base. Total fluid used = 1.5 gallons. Final pH = 5.0.
To dry the leaves, plant was hung upside-down in a well-ventilated room. After a week, the dried plant leaves were crumbled and stored in an airtight container.
To extract the steviol glycosides from the dried leaves, I followed the following procedure: