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Silphium Seeds - Cup Plant
SEASON
Perennial
USDA ZONES
4 - 9
HEIGHT
40 - 90 inches
BLOOM SEASON
Late spring through summer
BLOOM COLOR
Yellow
ENVIRONMENT
Full sun
SOIL TYPE
Loamy, moist to slightly dry, pH 6.1 - 7.4
DEER RESISTANT
Yes
FOLIAGE COLOR
Dark green
About...
Silphium (Silphium Perfoliatum) - This towering, flowering plant is a native of the tall grass prairie and readily establishes from Silphium seeds. It is commonly known as Cup Plant and is a perennial giant which has yellow daisy-like flowers. The flowers measure 3 - 4 inches across and attract bees and birds.
MORE SILPHIUM OPTIONS
Planting Directions
TEMPERATURE
24 to 39F for 4 - 8 weeks, then moved to 68F for germination
AVERAGE GERM TIME
21 - 28 days after cold period
LIGHT REQUIRED
Yes
DEPTH
1/8 - 1/4 inch
SOWING RATE
1 ounce per 250 square feet
MOISTURE
Keep seeds moist until germination
PLANT SPACING
15 - 18 inches
Silphium (Silphium Perfoliatum) - This towering, flowering plant is a native of the tall grass prairie and readily establishes from Silphium seeds. It is commonly known as Cup Plant and is a perennial giant which has yellow daisy-like flowers. The flowers measure 3 - 4 inches across and attract bees and birds. The name comes from the large leaves that are on opposite sides of the stem and are fused together at their base. This base forms a cup that collects water from the morning dew. Birds and insects seek out the collected water.
The Silphium Cup Plant prefers sunny settings and moist loamy soil. The root system consists of a long central tap root and many shallow rhizomes. The rhizomes help to spread the plant. The Silphium Perfoliatum Cup Plant will often form substantial colonies due to the spreading ability.
How To Grow Silphium: Sow Silphium Perfoliatum seeds directly outdoors in late fall or early winter. These particular flower seeds do well with a cold, dormant planting as the cold temperatures actually help break the flower seed of its dormancy. Once spring arrives and temperatures warm, the Cup Plant seeds will germinate quickly. Prepare the outdoor soil by removing weeds and loosening. Silphium Cup Plant seed can be raked into loosened soil and covered 1/8 - 1/4 inch.
Approximately 2,000 seeds per ounce.