The last time I grew radishes, I used the Cherry Belle and French Breakfast varieties. Cherry Belle grew better in rockwool, and French Breakfast grew better in perlite. Since perlite is cheaper, I will see how it does as the growing medium for these Crimson Giant radishes.
Mar 20, 2016 = Day 0. Plants started from seed (Botanical Interests). Seeds sowed in perlite in 2-inch net-pots. A slice of rockwool (5 mm in thickness) was placed at the bottom of the net-pot to help keep the perlite from falling out. Moistened with dilute fertilizer solution: 1.2 mL Dyna-Gro GROW 7-9-5, 0.8 mL pH Down per gallon of tap water. N-P-K (in ppm): 22-12-13. pH = 6.0.
Mar 25 = Day 5. 1 out of 8 plants has germinated, placed directly under a fluorescent light (2 ft. T8 bulb, 17W, 6500k) for 16 hours per day.
Mar 29 = Day 9. Still only 1 out of 8 plants have germinated, not sure what went wrong here. It could be that the ‘perched water table’ in the perlite was too high, drowning the seeds. Rockwool may give more dependable results for seed starting. In any case, I transferred the 1 net-pot that had seedlings into a 0.5 gallon glass jar. Hydroponic solution composed of 0.5 gal (1.9 L) tap water, 1 g MasterBlend 4-18-38, 1 g calcium nitrate, 0.5 g magnesium sulfate, 0.1 mL Dyna-Gro Pro-TeKt, 0.5 mL pH Down. N-P-K (in ppm): 103-41-168. pH = 6.0.
Apr 5 = Day 16. Jar was accidentally knocked over, plants are ruined. Growing these Crimson Giant radishes was just not meant to be. I will try again some other time.