I’m currently growing Cherry Belle radishes, so I figured I’d start up another variety, French Breakfast, for the sake of comparison. These will also be grown in 2 types of media: rockwool and perlite.
Jan 7, 2016 = Day 0. Plants started from seed (Botanical Interests). Seeds sowed in 1.5-inch rockwool cubes or perlite in 2-inch net-pots. In the case of perlite, a thin slice (1/4-inch) of rockwool was placed at the bottom of the net-pot to help keep the perlite from falling out. Moistened with dilute fertilizer solution: 1 mL (1/5 tsp) Dyna-Gro Liquid Grow, 1 mL pH Down per gallon of tap water. Nutrient concentrations (in ppm): N 18, P 24, K 13, Ca 5, Mg 1, S 0.13, Fe 0.26, Mn 0.13, B 0.05, Zn 0.13, Cu 0.13, Mo 0.002, Ni 0.0003, Co 0.004. pH = 6.0.
Jan 9 = Day 2. Plants germinated, placed directly under a fluorescent light (2 ft. T8 bulb, 17W, 6500k) for 14-16 hours per day.
Jan 11 = Day 4. One of the rockwool seedlings looked strange, had some sort of fungus attached to stem. Discarded, started a new one with fresh rockwool cube and seeds.
Jan 13 = Day 6. Installed plants into small rectangular 1.5-gallon container (the same container currently growing the Cherry Belle radishes). Hydroponic solution composed of 1.125 gal (18 cups) tap water, 6.75 mL Dyna-Gro Liquid Grow, 0.225 mL Dyna-Gro Pro-TeKt. Nutrient concentrations (in ppm): N 111, P 143, K 81, Ca 32, Mg 8, S 0.8, Fe 1.6, Mn 0.8, B 0.3, Zn 0.8, Cu 0.8, Mo 0.01, Ni 0.002, Co 0.024, Si 4. pH = 6.5.
Jan 20 = Day 13. Thinned to 1 plant per net-pot. Transferred plants to indoor grow room, where they get 8 hours LED light per day, plus 2 hours of sunlight.
Feb 9 = Day 34. Almost all of the hydroponic fluid was gone, so I added 0.25 gallons of fresh fluid.
Feb 17 = Day 42. Fluid reservoir was empty again, so I added another 0.25 gallons. Radishes growing in perlite are far more developed than those growing in rockwool.
The radish experiment has now concluded. Looks like the radishes grown in perlite did better than those grown in rockwool, but this is the opposite of the result I obtained with the Cherry Belle radishes here. Clearly, I will need to repeat this experiment a few more times to get a definitive result, but it seems that both rockwool and perlite may both be fine for growing radishes.