Phlox is very sensitive to high soluble salts so electrical conductivity should be lower than 0.75. Test the medium before sowing. Excessive salts can damage roots and lead to root rot diseases. Provide high humidity to the seed, but do not saturate the medium. The seed prefers a drier medium for germination.
Darkness is required for germination.
Seed can be covered with No. 2 coarse-grade vermiculite, which helps maintain high humidity and good air circulation around the seed. Once germination occurs, provide supplemental light at 450-700 footcandles to improve uniformity of developing seedlings. Stage 1 . Maintain temperature at 62F-66F. Roots emerge and penetrate the medium in five to seven days. Stage 2 .