10-30 days after chill; can be erratic
Stratify for 3 weeks at 35-40°F in late winter. To stratify, place seeds in dampened vermiculite or clean sand, enclose in a plastic bag and refrigerate. Eight to 10 weeks before last frost, remove pre-chilled seeds from refrigerator and sow. Cover with humidity dome and keep at 60-70°F. Transplant seedlings as they appear; anywhere from 2-8 weeks—be patient.
Direct sow in fall or earliest spring, or wintersow into pots in the shade, covered with a thin layer of clean sand and a wire screen to keep out mice and voles. Check for moisture at regular intervals.
PLACEMENT & CULTIVATION
Horned poppy has large, deeply cut, thickly felted leaves that add a dramatic form to rock gardens and gravelly dry borders, A biennial to short-lived perennial, site where drainage is perfect, particularly during the winter months. Deadhead to prolong bloom, and allow a few of the sizeable horned seed capsules to drop seed to help renew plantings.
Water regularly while establishing, then only during especially dry, hot spells. Do not allow to remain wet, especially during winter months.
If soil is especially poor, mix in an inch or two of compost prior to planting.
Diseases & Pests:
Excess soil moisture can cause rot; ensure the area is well-drained.