Dry stratification is done by placing dry seed in the refrigerator for 30 or more days. Ernst Seeds in the Media; Press Releases; Upcoming Events; Social Media Hub; Select Page. Need sandy or gravelly soils (except the Clay form which does well in heavier soils including dry clay.). Reproduction: The seeds grow in pods called follicles, which begin to form in late summer. If you’re concerned about soil quality, amending with compost is a good idea.